| Message ID | 20210913131118.330293390@linuxfoundation.org |
|---|---|
| State | New |
| Headers | show |
| Series | None | expand |
Hi, On Mon, Sep 13, 2021 at 6:51 AM Greg Kroah-Hartman <gregkh@linuxfoundation.org> wrote: > > From: Douglas Anderson <dianders@chromium.org> > > [ Upstream commit a70e558c151043ce46a5e5999f4310e0b3551f57 ] > > This is really just a revert of commit 58074b08c04a ("drm/bridge: > ti-sn65dsi86: Read EDID blob over DDC"), resolving conflicts. > > The old code failed to read the EDID properly in a very important > case: before the bridge's pre_enable() was called. The way things need > to work: > 1. Read the EDID. > 2. Based on the EDID, decide on video settings and pixel clock. > 3. Enable the bridge w/ the desired settings. > > The way things were working: > 1. Try to read the EDID but fail; fall back to hardcoded values. > 2. Based on hardcoded values, decide on video settings and pixel clock. > 3. Enable the bridge w/ the desired settings. > 4. Try again to read the EDID, it works now! > 5. Realize that the hardcoded settings weren't quite right. > 6. Disable / reenable the bridge w/ the right settings. > > The reasons for the failures were twofold: > a) Since we never ran the bridge chip's pre-enable then we never set > the bit to ignore HPD. This meant the bridge chip didn't even _try_ > to go out on the bus and communicate with the panel. > b) Even if we fixed things to ignore HPD, the EDID still wouldn't read > if the panel wasn't on. > > Instead of reverting the code, we could fix it to set the HPD bit and > also power on the panel. However, it also works nicely to just let the > panel code read the EDID. Now that we've split the driver up we can > expose the DDC AUX channel bus to the panel node. The panel can take > charge of reading the EDID. > > NOTE: in order for things to work, anyone that needs to read the EDID > will need to instantiate their panel using the new DP AUX bus (AKA by > listing their panel under the "aux-bus" node of the bridge chip in the > device tree). > > In the future if we want to use the bridge chip to provide a full > external DP port (which won't have a panel) then we will have to > conditinally add EDID reading back in. > > Suggested-by: Andrzej Hajda <a.hajda@samsung.com> > Signed-off-by: Douglas Anderson <dianders@chromium.org> > Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org> > Link: https://patchwork.freedesktop.org/patch/msgid/20210611101711.v10.9.I9330684c25f65bb318eff57f0616500f83eac3cc@changeid > Signed-off-by: Sasha Levin <sashal@kernel.org> > --- > drivers/gpu/drm/bridge/ti-sn65dsi86.c | 22 ---------------------- > 1 file changed, 22 deletions(-) I guess it's not a huge deal, but I did respond to Sasha and request that this patch be dropped from the stable queue unless the whole big pile of patches was being backported. See: https://lore.kernel.org/lkml/CAD=FV=U2dGjeEzp+K1vnLTj8oPJ-GKBTTKz2XQ1OZ7QF_sTHuw@mail.gmail.com/ I said: > I would suggest against backporting this one unless you're going to > backport the whole pile of DP AUX bus patches, which probably doesn't > make sense for stable. Even though the old EDID reading was broken for > the first read, it still worked for later reads. ...and the first read . didn't crash or anything--it just timed out. -Doug
Hi, On Mon, Sep 13, 2021 at 9:09 AM Greg Kroah-Hartman <gregkh@linuxfoundation.org> wrote: > > On Mon, Sep 13, 2021 at 06:57:20AM -0700, Doug Anderson wrote: > > Hi, > > > > On Mon, Sep 13, 2021 at 6:51 AM Greg Kroah-Hartman > > <gregkh@linuxfoundation.org> wrote: > > > > > > From: Douglas Anderson <dianders@chromium.org> > > > > > > [ Upstream commit a70e558c151043ce46a5e5999f4310e0b3551f57 ] > > > > > > This is really just a revert of commit 58074b08c04a ("drm/bridge: > > > ti-sn65dsi86: Read EDID blob over DDC"), resolving conflicts. > > > > > > The old code failed to read the EDID properly in a very important > > > case: before the bridge's pre_enable() was called. The way things need > > > to work: > > > 1. Read the EDID. > > > 2. Based on the EDID, decide on video settings and pixel clock. > > > 3. Enable the bridge w/ the desired settings. > > > > > > The way things were working: > > > 1. Try to read the EDID but fail; fall back to hardcoded values. > > > 2. Based on hardcoded values, decide on video settings and pixel clock. > > > 3. Enable the bridge w/ the desired settings. > > > 4. Try again to read the EDID, it works now! > > > 5. Realize that the hardcoded settings weren't quite right. > > > 6. Disable / reenable the bridge w/ the right settings. > > > > > > The reasons for the failures were twofold: > > > a) Since we never ran the bridge chip's pre-enable then we never set > > > the bit to ignore HPD. This meant the bridge chip didn't even _try_ > > > to go out on the bus and communicate with the panel. > > > b) Even if we fixed things to ignore HPD, the EDID still wouldn't read > > > if the panel wasn't on. > > > > > > Instead of reverting the code, we could fix it to set the HPD bit and > > > also power on the panel. However, it also works nicely to just let the > > > panel code read the EDID. Now that we've split the driver up we can > > > expose the DDC AUX channel bus to the panel node. The panel can take > > > charge of reading the EDID. > > > > > > NOTE: in order for things to work, anyone that needs to read the EDID > > > will need to instantiate their panel using the new DP AUX bus (AKA by > > > listing their panel under the "aux-bus" node of the bridge chip in the > > > device tree). > > > > > > In the future if we want to use the bridge chip to provide a full > > > external DP port (which won't have a panel) then we will have to > > > conditinally add EDID reading back in. > > > > > > Suggested-by: Andrzej Hajda <a.hajda@samsung.com> > > > Signed-off-by: Douglas Anderson <dianders@chromium.org> > > > Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org> > > > Link: https://patchwork.freedesktop.org/patch/msgid/20210611101711.v10.9.I9330684c25f65bb318eff57f0616500f83eac3cc@changeid > > > Signed-off-by: Sasha Levin <sashal@kernel.org> > > > --- > > > drivers/gpu/drm/bridge/ti-sn65dsi86.c | 22 ---------------------- > > > 1 file changed, 22 deletions(-) > > > > I guess it's not a huge deal, but I did respond to Sasha and request > > that this patch be dropped from the stable queue unless the whole big > > pile of patches was being backported. See: > > > > https://lore.kernel.org/lkml/CAD=FV=U2dGjeEzp+K1vnLTj8oPJ-GKBTTKz2XQ1OZ7QF_sTHuw@mail.gmail.com/ > > > > I said: > > > > > I would suggest against backporting this one unless you're going to > > > backport the whole pile of DP AUX bus patches, which probably doesn't > > > make sense for stable. Even though the old EDID reading was broken for > > > the first read, it still worked for later reads. ...and the first read > > . didn't crash or anything--it just timed out. > > I see a "bunch" of patches for this driver in this -rc, did Sasha not > get them all? If not, I can drop this one, but maybe it was needed for > the follow-on patches? It's been a long journey trying to make this bridge work better. I think the easiest way to say it is that if you don't have the parent of ${SUBJECT} patch, AKA: e0bbcc6233f7 drm/bridge: ti-sn65dsi86: Add support for the DP AUX bus ...then you don't have DP AUX bus support and you shouldn't take ${SUBJECT} patch. If you have that patch and it compiles / builds then it means that you have all the proper dependencies. However, there are _a lot_ of dependencies and I wouldn't suggest picking them all to stable unless it's critical for someone. -Doug
On Mon, Sep 13, 2021 at 09:31:03AM -0700, Doug Anderson wrote: > Hi, > > On Mon, Sep 13, 2021 at 9:09 AM Greg Kroah-Hartman > <gregkh@linuxfoundation.org> wrote: > > > > On Mon, Sep 13, 2021 at 06:57:20AM -0700, Doug Anderson wrote: > > > Hi, > > > > > > On Mon, Sep 13, 2021 at 6:51 AM Greg Kroah-Hartman > > > <gregkh@linuxfoundation.org> wrote: > > > > > > > > From: Douglas Anderson <dianders@chromium.org> > > > > > > > > [ Upstream commit a70e558c151043ce46a5e5999f4310e0b3551f57 ] > > > > > > > > This is really just a revert of commit 58074b08c04a ("drm/bridge: > > > > ti-sn65dsi86: Read EDID blob over DDC"), resolving conflicts. > > > > > > > > The old code failed to read the EDID properly in a very important > > > > case: before the bridge's pre_enable() was called. The way things need > > > > to work: > > > > 1. Read the EDID. > > > > 2. Based on the EDID, decide on video settings and pixel clock. > > > > 3. Enable the bridge w/ the desired settings. > > > > > > > > The way things were working: > > > > 1. Try to read the EDID but fail; fall back to hardcoded values. > > > > 2. Based on hardcoded values, decide on video settings and pixel clock. > > > > 3. Enable the bridge w/ the desired settings. > > > > 4. Try again to read the EDID, it works now! > > > > 5. Realize that the hardcoded settings weren't quite right. > > > > 6. Disable / reenable the bridge w/ the right settings. > > > > > > > > The reasons for the failures were twofold: > > > > a) Since we never ran the bridge chip's pre-enable then we never set > > > > the bit to ignore HPD. This meant the bridge chip didn't even _try_ > > > > to go out on the bus and communicate with the panel. > > > > b) Even if we fixed things to ignore HPD, the EDID still wouldn't read > > > > if the panel wasn't on. > > > > > > > > Instead of reverting the code, we could fix it to set the HPD bit and > > > > also power on the panel. However, it also works nicely to just let the > > > > panel code read the EDID. Now that we've split the driver up we can > > > > expose the DDC AUX channel bus to the panel node. The panel can take > > > > charge of reading the EDID. > > > > > > > > NOTE: in order for things to work, anyone that needs to read the EDID > > > > will need to instantiate their panel using the new DP AUX bus (AKA by > > > > listing their panel under the "aux-bus" node of the bridge chip in the > > > > device tree). > > > > > > > > In the future if we want to use the bridge chip to provide a full > > > > external DP port (which won't have a panel) then we will have to > > > > conditinally add EDID reading back in. > > > > > > > > Suggested-by: Andrzej Hajda <a.hajda@samsung.com> > > > > Signed-off-by: Douglas Anderson <dianders@chromium.org> > > > > Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org> > > > > Link: https://patchwork.freedesktop.org/patch/msgid/20210611101711.v10.9.I9330684c25f65bb318eff57f0616500f83eac3cc@changeid > > > > Signed-off-by: Sasha Levin <sashal@kernel.org> > > > > --- > > > > drivers/gpu/drm/bridge/ti-sn65dsi86.c | 22 ---------------------- > > > > 1 file changed, 22 deletions(-) > > > > > > I guess it's not a huge deal, but I did respond to Sasha and request > > > that this patch be dropped from the stable queue unless the whole big > > > pile of patches was being backported. See: > > > > > > https://lore.kernel.org/lkml/CAD=FV=U2dGjeEzp+K1vnLTj8oPJ-GKBTTKz2XQ1OZ7QF_sTHuw@mail.gmail.com/ > > > > > > I said: > > > > > > > I would suggest against backporting this one unless you're going to > > > > backport the whole pile of DP AUX bus patches, which probably doesn't > > > > make sense for stable. Even though the old EDID reading was broken for > > > > the first read, it still worked for later reads. ...and the first read > > > . didn't crash or anything--it just timed out. > > > > I see a "bunch" of patches for this driver in this -rc, did Sasha not > > get them all? If not, I can drop this one, but maybe it was needed for > > the follow-on patches? > > It's been a long journey trying to make this bridge work better. I > think the easiest way to say it is that if you don't have the parent > of ${SUBJECT} patch, AKA: > > e0bbcc6233f7 drm/bridge: ti-sn65dsi86: Add support for the DP AUX bus > > ...then you don't have DP AUX bus support and you shouldn't take > ${SUBJECT} patch. If you have that patch and it compiles / builds then > it means that you have all the proper dependencies. However, there are > _a lot_ of dependencies and I wouldn't suggest picking them all to > stable unless it's critical for someone. I tried to drop this one, and it turned out to be a depandancy for another patch for this driver. And that was another dependancy. So I've now dropped all of these from the queue. Here are the commits I dropped. If you think any should be added back, please let us know: 05a7f4a8dff1 ("devlink: Break parameter notification sequence to be before/after unload/load driver") e183bf31cf0d ("drm/bridge: ti-sn65dsi86: Add some 100 us delays") c7782443a889 ("drm/bridge: ti-sn65dsi86: Avoid creating multiple connectors") a70e558c1510 ("drm/bridge: ti-sn65dsi86: Don't read EDID blob over DDC") acb06210b096 ("drm/bridge: ti-sn65dsi86: Fix power off sequence") 4c1b3d94bf63 ("drm/bridge: ti-sn65dsi86: Improve probe errors with dev_err_probe()") 4e5763f03e10 ("drm/bridge: ti-sn65dsi86: Wrap panel with panel-bridge") thanks, greg k-h
On Tue, Sep 14, 2021 at 06:27:08PM +0200, Greg Kroah-Hartman wrote: >On Mon, Sep 13, 2021 at 09:31:03AM -0700, Doug Anderson wrote: >> Hi, >> >> On Mon, Sep 13, 2021 at 9:09 AM Greg Kroah-Hartman >> <gregkh@linuxfoundation.org> wrote: >> > >> > On Mon, Sep 13, 2021 at 06:57:20AM -0700, Doug Anderson wrote: >> > > Hi, >> > > >> > > On Mon, Sep 13, 2021 at 6:51 AM Greg Kroah-Hartman >> > > <gregkh@linuxfoundation.org> wrote: >> > > > >> > > > From: Douglas Anderson <dianders@chromium.org> >> > > > >> > > > [ Upstream commit a70e558c151043ce46a5e5999f4310e0b3551f57 ] >> > > > >> > > > This is really just a revert of commit 58074b08c04a ("drm/bridge: >> > > > ti-sn65dsi86: Read EDID blob over DDC"), resolving conflicts. >> > > > >> > > > The old code failed to read the EDID properly in a very important >> > > > case: before the bridge's pre_enable() was called. The way things need >> > > > to work: >> > > > 1. Read the EDID. >> > > > 2. Based on the EDID, decide on video settings and pixel clock. >> > > > 3. Enable the bridge w/ the desired settings. >> > > > >> > > > The way things were working: >> > > > 1. Try to read the EDID but fail; fall back to hardcoded values. >> > > > 2. Based on hardcoded values, decide on video settings and pixel clock. >> > > > 3. Enable the bridge w/ the desired settings. >> > > > 4. Try again to read the EDID, it works now! >> > > > 5. Realize that the hardcoded settings weren't quite right. >> > > > 6. Disable / reenable the bridge w/ the right settings. >> > > > >> > > > The reasons for the failures were twofold: >> > > > a) Since we never ran the bridge chip's pre-enable then we never set >> > > > the bit to ignore HPD. This meant the bridge chip didn't even _try_ >> > > > to go out on the bus and communicate with the panel. >> > > > b) Even if we fixed things to ignore HPD, the EDID still wouldn't read >> > > > if the panel wasn't on. >> > > > >> > > > Instead of reverting the code, we could fix it to set the HPD bit and >> > > > also power on the panel. However, it also works nicely to just let the >> > > > panel code read the EDID. Now that we've split the driver up we can >> > > > expose the DDC AUX channel bus to the panel node. The panel can take >> > > > charge of reading the EDID. >> > > > >> > > > NOTE: in order for things to work, anyone that needs to read the EDID >> > > > will need to instantiate their panel using the new DP AUX bus (AKA by >> > > > listing their panel under the "aux-bus" node of the bridge chip in the >> > > > device tree). >> > > > >> > > > In the future if we want to use the bridge chip to provide a full >> > > > external DP port (which won't have a panel) then we will have to >> > > > conditinally add EDID reading back in. >> > > > >> > > > Suggested-by: Andrzej Hajda <a.hajda@samsung.com> >> > > > Signed-off-by: Douglas Anderson <dianders@chromium.org> >> > > > Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org> >> > > > Link: https://patchwork.freedesktop.org/patch/msgid/20210611101711.v10.9.I9330684c25f65bb318eff57f0616500f83eac3cc@changeid >> > > > Signed-off-by: Sasha Levin <sashal@kernel.org> >> > > > --- >> > > > drivers/gpu/drm/bridge/ti-sn65dsi86.c | 22 ---------------------- >> > > > 1 file changed, 22 deletions(-) >> > > >> > > I guess it's not a huge deal, but I did respond to Sasha and request >> > > that this patch be dropped from the stable queue unless the whole big >> > > pile of patches was being backported. See: >> > > >> > > https://lore.kernel.org/lkml/CAD=FV=U2dGjeEzp+K1vnLTj8oPJ-GKBTTKz2XQ1OZ7QF_sTHuw@mail.gmail.com/ >> > > >> > > I said: >> > > >> > > > I would suggest against backporting this one unless you're going to >> > > > backport the whole pile of DP AUX bus patches, which probably doesn't >> > > > make sense for stable. Even though the old EDID reading was broken for >> > > > the first read, it still worked for later reads. ...and the first read >> > > . didn't crash or anything--it just timed out. >> > >> > I see a "bunch" of patches for this driver in this -rc, did Sasha not >> > get them all? If not, I can drop this one, but maybe it was needed for >> > the follow-on patches? >> >> It's been a long journey trying to make this bridge work better. I >> think the easiest way to say it is that if you don't have the parent >> of ${SUBJECT} patch, AKA: >> >> e0bbcc6233f7 drm/bridge: ti-sn65dsi86: Add support for the DP AUX bus >> >> ...then you don't have DP AUX bus support and you shouldn't take >> ${SUBJECT} patch. If you have that patch and it compiles / builds then >> it means that you have all the proper dependencies. However, there are >> _a lot_ of dependencies and I wouldn't suggest picking them all to >> stable unless it's critical for someone. > >I tried to drop this one, and it turned out to be a depandancy for >another patch for this driver. And that was another dependancy. So >I've now dropped all of these from the queue. > >Here are the commits I dropped. If you think any should be added back, >please let us know: > >05a7f4a8dff1 ("devlink: Break parameter notification sequence to be before/after unload/load driver") >e183bf31cf0d ("drm/bridge: ti-sn65dsi86: Add some 100 us delays") >c7782443a889 ("drm/bridge: ti-sn65dsi86: Avoid creating multiple connectors") >a70e558c1510 ("drm/bridge: ti-sn65dsi86: Don't read EDID blob over DDC") >acb06210b096 ("drm/bridge: ti-sn65dsi86: Fix power off sequence") >4c1b3d94bf63 ("drm/bridge: ti-sn65dsi86: Improve probe errors with dev_err_probe()") >4e5763f03e10 ("drm/bridge: ti-sn65dsi86: Wrap panel with panel-bridge") Thanks! And yes, I dropped the patch based on the request but it snuck in as a dependency for a few patches with a Fixes tag. -- Thanks, Sasha
Hi, On Tue, Sep 14, 2021 at 9:27 AM Greg Kroah-Hartman <gregkh@linuxfoundation.org> wrote: > > On Mon, Sep 13, 2021 at 09:31:03AM -0700, Doug Anderson wrote: > > Hi, > > > > On Mon, Sep 13, 2021 at 9:09 AM Greg Kroah-Hartman > > <gregkh@linuxfoundation.org> wrote: > > > > > > On Mon, Sep 13, 2021 at 06:57:20AM -0700, Doug Anderson wrote: > > > > Hi, > > > > > > > > On Mon, Sep 13, 2021 at 6:51 AM Greg Kroah-Hartman > > > > <gregkh@linuxfoundation.org> wrote: > > > > > > > > > > From: Douglas Anderson <dianders@chromium.org> > > > > > > > > > > [ Upstream commit a70e558c151043ce46a5e5999f4310e0b3551f57 ] > > > > > > > > > > This is really just a revert of commit 58074b08c04a ("drm/bridge: > > > > > ti-sn65dsi86: Read EDID blob over DDC"), resolving conflicts. > > > > > > > > > > The old code failed to read the EDID properly in a very important > > > > > case: before the bridge's pre_enable() was called. The way things need > > > > > to work: > > > > > 1. Read the EDID. > > > > > 2. Based on the EDID, decide on video settings and pixel clock. > > > > > 3. Enable the bridge w/ the desired settings. > > > > > > > > > > The way things were working: > > > > > 1. Try to read the EDID but fail; fall back to hardcoded values. > > > > > 2. Based on hardcoded values, decide on video settings and pixel clock. > > > > > 3. Enable the bridge w/ the desired settings. > > > > > 4. Try again to read the EDID, it works now! > > > > > 5. Realize that the hardcoded settings weren't quite right. > > > > > 6. Disable / reenable the bridge w/ the right settings. > > > > > > > > > > The reasons for the failures were twofold: > > > > > a) Since we never ran the bridge chip's pre-enable then we never set > > > > > the bit to ignore HPD. This meant the bridge chip didn't even _try_ > > > > > to go out on the bus and communicate with the panel. > > > > > b) Even if we fixed things to ignore HPD, the EDID still wouldn't read > > > > > if the panel wasn't on. > > > > > > > > > > Instead of reverting the code, we could fix it to set the HPD bit and > > > > > also power on the panel. However, it also works nicely to just let the > > > > > panel code read the EDID. Now that we've split the driver up we can > > > > > expose the DDC AUX channel bus to the panel node. The panel can take > > > > > charge of reading the EDID. > > > > > > > > > > NOTE: in order for things to work, anyone that needs to read the EDID > > > > > will need to instantiate their panel using the new DP AUX bus (AKA by > > > > > listing their panel under the "aux-bus" node of the bridge chip in the > > > > > device tree). > > > > > > > > > > In the future if we want to use the bridge chip to provide a full > > > > > external DP port (which won't have a panel) then we will have to > > > > > conditinally add EDID reading back in. > > > > > > > > > > Suggested-by: Andrzej Hajda <a.hajda@samsung.com> > > > > > Signed-off-by: Douglas Anderson <dianders@chromium.org> > > > > > Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org> > > > > > Link: https://patchwork.freedesktop.org/patch/msgid/20210611101711.v10.9.I9330684c25f65bb318eff57f0616500f83eac3cc@changeid > > > > > Signed-off-by: Sasha Levin <sashal@kernel.org> > > > > > --- > > > > > drivers/gpu/drm/bridge/ti-sn65dsi86.c | 22 ---------------------- > > > > > 1 file changed, 22 deletions(-) > > > > > > > > I guess it's not a huge deal, but I did respond to Sasha and request > > > > that this patch be dropped from the stable queue unless the whole big > > > > pile of patches was being backported. See: > > > > > > > > https://lore.kernel.org/lkml/CAD=FV=U2dGjeEzp+K1vnLTj8oPJ-GKBTTKz2XQ1OZ7QF_sTHuw@mail.gmail.com/ > > > > > > > > I said: > > > > > > > > > I would suggest against backporting this one unless you're going to > > > > > backport the whole pile of DP AUX bus patches, which probably doesn't > > > > > make sense for stable. Even though the old EDID reading was broken for > > > > > the first read, it still worked for later reads. ...and the first read > > > > . didn't crash or anything--it just timed out. > > > > > > I see a "bunch" of patches for this driver in this -rc, did Sasha not > > > get them all? If not, I can drop this one, but maybe it was needed for > > > the follow-on patches? > > > > It's been a long journey trying to make this bridge work better. I > > think the easiest way to say it is that if you don't have the parent > > of ${SUBJECT} patch, AKA: > > > > e0bbcc6233f7 drm/bridge: ti-sn65dsi86: Add support for the DP AUX bus > > > > ...then you don't have DP AUX bus support and you shouldn't take > > ${SUBJECT} patch. If you have that patch and it compiles / builds then > > it means that you have all the proper dependencies. However, there are > > _a lot_ of dependencies and I wouldn't suggest picking them all to > > stable unless it's critical for someone. > > I tried to drop this one, and it turned out to be a depandancy for > another patch for this driver. And that was another dependancy. So > I've now dropped all of these from the queue. Ugh. :( > Here are the commits I dropped. If you think any should be added back, > please let us know: > > 05a7f4a8dff1 ("devlink: Break parameter notification sequence to be before/after unload/load driver") I don't understand what the "devlink" patch had to do with ti-sn65dsi86. I'll assume you didn't intend to have it in your list. > e183bf31cf0d ("drm/bridge: ti-sn65dsi86: Add some 100 us delays") > c7782443a889 ("drm/bridge: ti-sn65dsi86: Avoid creating multiple connectors") > a70e558c1510 ("drm/bridge: ti-sn65dsi86: Don't read EDID blob over DDC") > acb06210b096 ("drm/bridge: ti-sn65dsi86: Fix power off sequence") > 4c1b3d94bf63 ("drm/bridge: ti-sn65dsi86: Improve probe errors with dev_err_probe()") > 4e5763f03e10 ("drm/bridge: ti-sn65dsi86: Wrap panel with panel-bridge") I'd say it's OK to drop these. If someone demonstrates a need for them on stable channel then I can help with backporting, but otherwise I can't see that it's worth it. Basically: 1. I think ${SUBJECT} patch without full DP AUX support for people could cause a real regression if anyone is using this bridge chip on 5.14 stable. 2. I think picking back full DP AUX support is too heavy for a stable-channel backport without a demonstrated need. 3. Of the above patches, only one fixes a problem that was observed on real hardware ("Fix power off sequence"). That was only seen on a panel that _requires_ the full DP AUX support in order to work. Other ones are fixes based on code inspection, cleanups, or fixes for other patches in the series there. -Doug
On Tue, Sep 14, 2021 at 10:24:35AM -0700, Doug Anderson wrote: > Hi, > > On Tue, Sep 14, 2021 at 9:27 AM Greg Kroah-Hartman > <gregkh@linuxfoundation.org> wrote: > > > > On Mon, Sep 13, 2021 at 09:31:03AM -0700, Doug Anderson wrote: > > > Hi, > > > > > > On Mon, Sep 13, 2021 at 9:09 AM Greg Kroah-Hartman > > > <gregkh@linuxfoundation.org> wrote: > > > > > > > > On Mon, Sep 13, 2021 at 06:57:20AM -0700, Doug Anderson wrote: > > > > > Hi, > > > > > > > > > > On Mon, Sep 13, 2021 at 6:51 AM Greg Kroah-Hartman > > > > > <gregkh@linuxfoundation.org> wrote: > > > > > > > > > > > > From: Douglas Anderson <dianders@chromium.org> > > > > > > > > > > > > [ Upstream commit a70e558c151043ce46a5e5999f4310e0b3551f57 ] > > > > > > > > > > > > This is really just a revert of commit 58074b08c04a ("drm/bridge: > > > > > > ti-sn65dsi86: Read EDID blob over DDC"), resolving conflicts. > > > > > > > > > > > > The old code failed to read the EDID properly in a very important > > > > > > case: before the bridge's pre_enable() was called. The way things need > > > > > > to work: > > > > > > 1. Read the EDID. > > > > > > 2. Based on the EDID, decide on video settings and pixel clock. > > > > > > 3. Enable the bridge w/ the desired settings. > > > > > > > > > > > > The way things were working: > > > > > > 1. Try to read the EDID but fail; fall back to hardcoded values. > > > > > > 2. Based on hardcoded values, decide on video settings and pixel clock. > > > > > > 3. Enable the bridge w/ the desired settings. > > > > > > 4. Try again to read the EDID, it works now! > > > > > > 5. Realize that the hardcoded settings weren't quite right. > > > > > > 6. Disable / reenable the bridge w/ the right settings. > > > > > > > > > > > > The reasons for the failures were twofold: > > > > > > a) Since we never ran the bridge chip's pre-enable then we never set > > > > > > the bit to ignore HPD. This meant the bridge chip didn't even _try_ > > > > > > to go out on the bus and communicate with the panel. > > > > > > b) Even if we fixed things to ignore HPD, the EDID still wouldn't read > > > > > > if the panel wasn't on. > > > > > > > > > > > > Instead of reverting the code, we could fix it to set the HPD bit and > > > > > > also power on the panel. However, it also works nicely to just let the > > > > > > panel code read the EDID. Now that we've split the driver up we can > > > > > > expose the DDC AUX channel bus to the panel node. The panel can take > > > > > > charge of reading the EDID. > > > > > > > > > > > > NOTE: in order for things to work, anyone that needs to read the EDID > > > > > > will need to instantiate their panel using the new DP AUX bus (AKA by > > > > > > listing their panel under the "aux-bus" node of the bridge chip in the > > > > > > device tree). > > > > > > > > > > > > In the future if we want to use the bridge chip to provide a full > > > > > > external DP port (which won't have a panel) then we will have to > > > > > > conditinally add EDID reading back in. > > > > > > > > > > > > Suggested-by: Andrzej Hajda <a.hajda@samsung.com> > > > > > > Signed-off-by: Douglas Anderson <dianders@chromium.org> > > > > > > Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org> > > > > > > Link: https://patchwork.freedesktop.org/patch/msgid/20210611101711.v10.9.I9330684c25f65bb318eff57f0616500f83eac3cc@changeid > > > > > > Signed-off-by: Sasha Levin <sashal@kernel.org> > > > > > > --- > > > > > > drivers/gpu/drm/bridge/ti-sn65dsi86.c | 22 ---------------------- > > > > > > 1 file changed, 22 deletions(-) > > > > > > > > > > I guess it's not a huge deal, but I did respond to Sasha and request > > > > > that this patch be dropped from the stable queue unless the whole big > > > > > pile of patches was being backported. See: > > > > > > > > > > https://lore.kernel.org/lkml/CAD=FV=U2dGjeEzp+K1vnLTj8oPJ-GKBTTKz2XQ1OZ7QF_sTHuw@mail.gmail.com/ > > > > > > > > > > I said: > > > > > > > > > > > I would suggest against backporting this one unless you're going to > > > > > > backport the whole pile of DP AUX bus patches, which probably doesn't > > > > > > make sense for stable. Even though the old EDID reading was broken for > > > > > > the first read, it still worked for later reads. ...and the first read > > > > > . didn't crash or anything--it just timed out. > > > > > > > > I see a "bunch" of patches for this driver in this -rc, did Sasha not > > > > get them all? If not, I can drop this one, but maybe it was needed for > > > > the follow-on patches? > > > > > > It's been a long journey trying to make this bridge work better. I > > > think the easiest way to say it is that if you don't have the parent > > > of ${SUBJECT} patch, AKA: > > > > > > e0bbcc6233f7 drm/bridge: ti-sn65dsi86: Add support for the DP AUX bus > > > > > > ...then you don't have DP AUX bus support and you shouldn't take > > > ${SUBJECT} patch. If you have that patch and it compiles / builds then > > > it means that you have all the proper dependencies. However, there are > > > _a lot_ of dependencies and I wouldn't suggest picking them all to > > > stable unless it's critical for someone. > > > > I tried to drop this one, and it turned out to be a depandancy for > > another patch for this driver. And that was another dependancy. So > > I've now dropped all of these from the queue. > > Ugh. :( > > > > Here are the commits I dropped. If you think any should be added back, > > please let us know: > > > > 05a7f4a8dff1 ("devlink: Break parameter notification sequence to be before/after unload/load driver") > > I don't understand what the "devlink" patch had to do with > ti-sn65dsi86. I'll assume you didn't intend to have it in your list. Odd, good point, I think I messed up in removing too many patches, let me go add that back... thanks, greg k-h
diff --git a/drivers/gpu/drm/bridge/ti-sn65dsi86.c b/drivers/gpu/drm/bridge/ti-sn65dsi86.c index 45a2969afb2b..aef850296756 100644 --- a/drivers/gpu/drm/bridge/ti-sn65dsi86.c +++ b/drivers/gpu/drm/bridge/ti-sn65dsi86.c @@ -124,7 +124,6 @@ * @connector: Our connector. * @host_node: Remote DSI node. * @dsi: Our MIPI DSI source. - * @edid: Detected EDID of eDP panel. * @refclk: Our reference clock. * @panel: Our panel. * @enable_gpio: The GPIO we toggle to enable the bridge. @@ -154,7 +153,6 @@ struct ti_sn65dsi86 { struct drm_dp_aux aux; struct drm_bridge bridge; struct drm_connector connector; - struct edid *edid; struct device_node *host_node; struct mipi_dsi_device *dsi; struct clk *refclk; @@ -403,24 +401,6 @@ connector_to_ti_sn65dsi86(struct drm_connector *connector) static int ti_sn_bridge_connector_get_modes(struct drm_connector *connector) { struct ti_sn65dsi86 *pdata = connector_to_ti_sn65dsi86(connector); - struct edid *edid = pdata->edid; - int num, ret; - - if (!edid) { - pm_runtime_get_sync(pdata->dev); - edid = pdata->edid = drm_get_edid(connector, &pdata->aux.ddc); - pm_runtime_put_autosuspend(pdata->dev); - } - - if (edid && drm_edid_is_valid(edid)) { - ret = drm_connector_update_edid_property(connector, edid); - if (!ret) { - num = drm_add_edid_modes(connector, edid); - if (num) - return num; - } - } - return drm_panel_get_modes(pdata->panel, connector); } @@ -1358,8 +1338,6 @@ static void ti_sn_bridge_remove(struct auxiliary_device *adev) mipi_dsi_device_unregister(pdata->dsi); } - kfree(pdata->edid); - drm_bridge_remove(&pdata->bridge); of_node_put(pdata->host_node);