| Message ID | 20220430175533.3817792-1-dmitry.baryshkov@linaro.org |
|---|---|
| State | Superseded |
| Headers | show |
| Series | [v2] drm/msm/dsi: use RMW cycles in dsi_update_dsc_timing | expand |
On 01/05/2022 23:41, Marijn Suijten wrote: > On 2022-04-30 22:28:42, Dmitry Baryshkov wrote: >> On 30/04/2022 21:58, Marijn Suijten wrote: >>> On 2022-04-30 20:55:33, Dmitry Baryshkov wrote: >>>> The downstream uses read-modify-write for updating command mode >>>> compression registers. Let's follow this approach. This also fixes the >>>> following warning: >>>> >>>> drivers/gpu/drm/msm/dsi/dsi_host.c:918:23: warning: variable 'reg_ctrl' set but not used [-Wunused-but-set-variable] >>>> >>>> Reported-by: kernel test robot <lkp@intel.com> >>>> Fixes: 08802f515c3c ("drm/msm/dsi: Add support for DSC configuration") >>>> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org> >>> >>> I pointed this out in review multiple times, so you'll obviously get my: >> >> I think I might have also pointed this out once (and then forgot to >> check that the issue was fixed by Vinod). >> >>> >>> Reviewed-by: Marijn Suijten <marijn.suijten@somainline.org> >>> >>> (But are you sure there's nothing else to clear in the 1st CTRL >>> register, only the lowest 16 bits? That should mean `reg` never >>> contains anything in 0xffff0000) >> >> Judging from the downstream the upper half conains the same fields, but >> used for other virtual channel. I didn't research what's the difference >> yet. All the dtsi files that I have here at hand use >> 'qcom,mdss-dsi-virtual-channel-id = <0>;' > > As replied to Abhinav I'm simply asking whether we should be strict > and add `reg & 0xffff` to prevent accidentally writing the top 16 bits, > which are stream 1. It doesn't seem like the current code can hit that > though, with all the macros using masks internally already; but it's > still a little scary since we're assuming the registers for VIDEO are > identical to CMD (as mentioned in the reply to Abhinav: I wonder if it's > possible to declare a a pair of bitfields as a single layout in the XML, > and reuse that across CMD's stream 0/1 and the VIDEO register). > >>> However, this seems to indicate that the DSC patch series has been >>> approved and merged somehow?? >> >> Pending inclusion, yes. If Vinod missed or ignored any other review >> points, please excuse Abhinav and me not noticing that. > > Vinod replied to most of the comments so I'll double-check if they were > applied in the way requested. Note that I don't always post a full > review up-front if it gets too noisy: I'll simply start out with the > most glaring issues and go in more detail in further revisions to > prevent drowning everyone in comments. > >> Can you please take a look at the latest revision posted, if there are >> any other missing points. Let's decide if there are grave issues or we >> can work them through. > > Thanks, I'll queue that up this week. One of my thus-far-unaddressed > issues with the patches which can't be addressed in hindsight is the > relatively lackluster commit messages: most happen to be repeating the > title in a slightly different way without any additional clarification, > which doesn't fit the upstream spirit at all. > I understand that the reference manuals can't be quoted nor am I asking > to, but a little more insight in the process and details of each patch > goes a very long way. Explain how certain calculations work or came to > be, link to public sources detailing the protocol, explain design > decisions or document how to use/test the feature and describe possible > limitations. > I usually link contributors to [1], but it's a bit of an odd read at > times. > > [1]: https://www.kernel.org/doc/html/latest/process/submitting-patches.html#describe-your-changes > > In any case, given that you've already sent this patch and another three > patches [2] fixing/cleaning up the series tells me it's far from ready. > Most of this should just be handled - or have been handled - in review > and amended? During the review time we agreed that [2] would come as a separate change It is an API change that would make using panel-bridge easier, but isn't otherwise required. I have been working towards more logical drm_bridge/drm_bridge_connector chains employing panel-bridge and display-connector where required, [2] is a part of that effort (as well as few other patches that hit dri-devel in the last few days). > > [2]: https://lore.kernel.org/linux-arm-msm/20220501151220.3999164-1-dmitry.baryshkov@linaro.org/T/#t > > I'll look through v14 again this week and let you know. > > - Marijn > >>> >>>> --- >>>> >>>> Changes since v1: >>>> - Fix c&p error and apply mask clear to reg_ctrl2 instead of reg_ctrl >>>> (Abhinav) >>>> >>>> --- >>>> drivers/gpu/drm/msm/dsi/dsi_host.c | 5 ++++- >>>> 1 file changed, 4 insertions(+), 1 deletion(-) >>>> >>>> diff --git a/drivers/gpu/drm/msm/dsi/dsi_host.c b/drivers/gpu/drm/msm/dsi/dsi_host.c >>>> index c983698d1384..a95d5df52653 100644 >>>> --- a/drivers/gpu/drm/msm/dsi/dsi_host.c >>>> +++ b/drivers/gpu/drm/msm/dsi/dsi_host.c >>>> @@ -961,10 +961,13 @@ static void dsi_update_dsc_timing(struct msm_dsi_host *msm_host, bool is_cmd_mod >>>> reg_ctrl = dsi_read(msm_host, REG_DSI_COMMAND_COMPRESSION_MODE_CTRL); >>>> reg_ctrl2 = dsi_read(msm_host, REG_DSI_COMMAND_COMPRESSION_MODE_CTRL2); >>>> >>>> + reg_ctrl &= ~0xffff; >>>> reg_ctrl |= reg; >>>> + >>>> + reg_ctrl2 &= ~DSI_COMMAND_COMPRESSION_MODE_CTRL2_STREAM0_SLICE_WIDTH__MASK; >>>> reg_ctrl2 |= DSI_COMMAND_COMPRESSION_MODE_CTRL2_STREAM0_SLICE_WIDTH(bytes_in_slice); >>>> >>>> - dsi_write(msm_host, REG_DSI_COMMAND_COMPRESSION_MODE_CTRL, reg); >>>> + dsi_write(msm_host, REG_DSI_COMMAND_COMPRESSION_MODE_CTRL, reg_ctrl); >>>> dsi_write(msm_host, REG_DSI_COMMAND_COMPRESSION_MODE_CTRL2, reg_ctrl2); >>>> } else { >>>> dsi_write(msm_host, REG_DSI_VIDEO_COMPRESSION_MODE_CTRL, reg); >>>> -- >>>> 2.35.1 >>>> >> >> >> -- >> With best wishes >> Dmitry
On 5/1/2022 1:06 PM, Marijn Suijten wrote: > On 2022-04-30 12:25:57, Abhinav Kumar wrote: >> >> >> On 4/30/2022 11:58 AM, Marijn Suijten wrote: >>> On 2022-04-30 20:55:33, Dmitry Baryshkov wrote: >>>> The downstream uses read-modify-write for updating command mode >>>> compression registers. Let's follow this approach. This also fixes the >>>> following warning: >>>> >>>> drivers/gpu/drm/msm/dsi/dsi_host.c:918:23: warning: variable 'reg_ctrl' set but not used [-Wunused-but-set-variable] >>>> >>>> Reported-by: kernel test robot <lkp@intel.com> >>>> Fixes: 08802f515c3c ("drm/msm/dsi: Add support for DSC configuration") >>>> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org> >>> >>> I pointed this out in review multiple times, so you'll obviously get my: >>> >>> Reviewed-by: Marijn Suijten <marijn.suijten@somainline.org> >>> >>> (But are you sure there's nothing else to clear in the 1st CTRL >>> register, only the lowest 16 bits? That should mean `reg` never >>> contains anything in 0xffff0000) >> >> The top 16 bits contain information for stream 1. >> >> Stream 1 is unused. And whatever is the reset value we should retain that. >> >> So this patch is correct. > > I was not debating the correctness of this patch, quite the contrary: > it's already much better than it was before. > > I'm simply asking whether we should prevent `reg` (not `reg_ctrl`!) > from having anything in the top 16 bits, which would overwrite the reset > value for stream 1 which you correctly say should be retained as it is. > It seems unlikely that this happens, but better be safe than sorry? Wouln't this macro already make sure that 'reg' doesnt have anything in the top 16 bits? Its doing a & with 0x00003f00 #define DSI_COMMAND_COMPRESSION_MODE_CTRL_STREAM0_DATATYPE__MASK 0x00003f00 #define DSI_COMMAND_COMPRESSION_MODE_CTRL_STREAM0_DATATYPE__SHIFT 8 static inline uint32_t DSI_COMMAND_COMPRESSION_MODE_CTRL_STREAM0_DATATYPE(uint32_t val) { return ((val) << DSI_COMMAND_COMPRESSION_MODE_CTRL_STREAM0_DATATYPE__SHIFT) & DSI_COMMAND_COMPRESSION_MODE_CTRL_STREAM0_DATATYPE__MASK; } Did you have anything else in mind? If so, please suggest. > > Looking at the DSI register definition for DSC [1] again, I wonder if > there's support for defining a common bitfield layout and reusing it > thrice: the two channels for CMD mode and a single use for VIDEO. Don't > think that'd make the kernel code better though if even possible at all. > We can have a common bitfield layout for the two channels for command mode. So we can do something like below for common fields: -static inline uint32_t DSI_COMMAND_COMPRESSION_MODE_CTRL_STREAM0_DATATYPE(uint32_t val) +static inline uint32_t DSI_COMMAND_COMPRESSION_MODE_CTRL_STREAM_DATATYPE(uint32_t val, uint32_t stream_id) { - return ((val) << DSI_COMMAND_COMPRESSION_MODE_CTRL_STREAM0_DATATYPE__SHIFT) & DSI_COMMAND_COMPRESSION_MODE_CTRL_STREAM0_DATATYPE__MASK; + return ((val) << (DSI_COMMAND_COMPRESSION_MODE_CTRL_STREAM0_DATATYPE__SHIFT + (stream_id * 16)) & DSI_COMMAND_COMPRESSION_MODE_CTRL_STREAM0_DATATYPE__MASK; } Video mode can also use all of these except for WC as that field is not present for cmd modes. This can go as a separate change . I can push this and perhaps get a Tested-by from Vinod as I dont have a setup to re-validate this. Thanks Abhinav > [1]: https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/14967/diffs > > - Marijn > >>> >>> However, this seems to indicate that the DSC patch series has been >>> approved and merged somehow?? >>> >>>> --- >>>> >>>> Changes since v1: >>>> - Fix c&p error and apply mask clear to reg_ctrl2 instead of reg_ctrl >>>> (Abhinav) >>>> >>>> --- >>>> drivers/gpu/drm/msm/dsi/dsi_host.c | 5 ++++- >>>> 1 file changed, 4 insertions(+), 1 deletion(-) >>>> >>>> diff --git a/drivers/gpu/drm/msm/dsi/dsi_host.c b/drivers/gpu/drm/msm/dsi/dsi_host.c >>>> index c983698d1384..a95d5df52653 100644 >>>> --- a/drivers/gpu/drm/msm/dsi/dsi_host.c >>>> +++ b/drivers/gpu/drm/msm/dsi/dsi_host.c >>>> @@ -961,10 +961,13 @@ static void dsi_update_dsc_timing(struct msm_dsi_host *msm_host, bool is_cmd_mod >>>> reg_ctrl = dsi_read(msm_host, REG_DSI_COMMAND_COMPRESSION_MODE_CTRL); >>>> reg_ctrl2 = dsi_read(msm_host, REG_DSI_COMMAND_COMPRESSION_MODE_CTRL2); >>>> >>>> + reg_ctrl &= ~0xffff; >>>> reg_ctrl |= reg; >>>> + >>>> + reg_ctrl2 &= ~DSI_COMMAND_COMPRESSION_MODE_CTRL2_STREAM0_SLICE_WIDTH__MASK; >>>> reg_ctrl2 |= DSI_COMMAND_COMPRESSION_MODE_CTRL2_STREAM0_SLICE_WIDTH(bytes_in_slice); >>>> >>>> - dsi_write(msm_host, REG_DSI_COMMAND_COMPRESSION_MODE_CTRL, reg); >>>> + dsi_write(msm_host, REG_DSI_COMMAND_COMPRESSION_MODE_CTRL, reg_ctrl); >>>> dsi_write(msm_host, REG_DSI_COMMAND_COMPRESSION_MODE_CTRL2, reg_ctrl2); >>>> } else { >>>> dsi_write(msm_host, REG_DSI_VIDEO_COMPRESSION_MODE_CTRL, reg); >>>> -- >>>> 2.35.1 >>>>
On 2022-05-01 16:56:45, Abhinav Kumar wrote: > [snip] > Wouln't this macro already make sure that 'reg' doesnt have anything in > the top 16 bits? Its doing a & with 0x00003f00 Like I said, it is unlikely that this happens, only if someone starts changing the code that assigns to `reg` which is unlikely to pass review anyway. > [snip] > We can have a common bitfield layout for the two channels for command mode. > > So we can do something like below for common fields: > > -static inline uint32_t > DSI_COMMAND_COMPRESSION_MODE_CTRL_STREAM0_DATATYPE(uint32_t val) > +static inline uint32_t > DSI_COMMAND_COMPRESSION_MODE_CTRL_STREAM_DATATYPE(uint32_t val, uint32_t > stream_id) > { > - return ((val) << > DSI_COMMAND_COMPRESSION_MODE_CTRL_STREAM0_DATATYPE__SHIFT) & > DSI_COMMAND_COMPRESSION_MODE_CTRL_STREAM0_DATATYPE__MASK; > + return ((val) << > (DSI_COMMAND_COMPRESSION_MODE_CTRL_STREAM0_DATATYPE__SHIFT + (stream_id > * 16)) & DSI_COMMAND_COMPRESSION_MODE_CTRL_STREAM0_DATATYPE__MASK; > } > > Video mode can also use all of these except for WC as that field is not > present for cmd modes. > > This can go as a separate change . > > I can push this and perhaps get a Tested-by from Vinod as I dont have a > setup to re-validate this. How would you represent this in XML? I was hoping for a method that allows to construct the value in a generic way, without register names, and then simply have a "register macro" that moves (and perhaps masks) the preconstructed value into the right place. A bit like how `enum`s are currently set up in XML, but with bit ranges for the values and macros to set a value. I think I've _partially_ found what I was looking for: a `<bitset>`. However, I don't know if we can utilize this multiple times within a single `reg32`, once with an offset for stream1. Alas, it's just bikeshedding at this point. - Marijn
On 2022-05-02 01:44:20, Dmitry Baryshkov wrote: > [sni[ > > In any case, given that you've already sent this patch and another three > > patches [2] fixing/cleaning up the series tells me it's far from ready. > > Most of this should just be handled - or have been handled - in review > > and amended? > > During the review time we agreed that [2] would come as a separate > change It is an API change that would make using panel-bridge easier, > but isn't otherwise required. > > I have been working towards more logical drm_bridge/drm_bridge_connector > chains employing panel-bridge and display-connector where required, [2] > is a part of that effort (as well as few other patches that hit > dri-devel in the last few days). I understand what is going on now. Since the DSC patches have already been queued up in the 5.19 pull I won't hurry to review them; rather will go over them when time allows me to play with the many phones here that require DSC for the screen to work. I've been told the series didn't result in positive screen output way back in its infancy, but I'll re-evaluate and send fixes or improvements if/when necessary. - Marijn
On 02/05/2022 11:34, Marijn Suijten wrote: > On 2022-05-01 16:56:45, Abhinav Kumar wrote: >> [snip] >> Wouln't this macro already make sure that 'reg' doesnt have anything in >> the top 16 bits? Its doing a & with 0x00003f00 > > Like I said, it is unlikely that this happens, only if someone starts > changing the code that assigns to `reg` which is unlikely to pass review > anyway. > >> [snip] >> We can have a common bitfield layout for the two channels for command mode. >> >> So we can do something like below for common fields: >> >> -static inline uint32_t >> DSI_COMMAND_COMPRESSION_MODE_CTRL_STREAM0_DATATYPE(uint32_t val) >> +static inline uint32_t >> DSI_COMMAND_COMPRESSION_MODE_CTRL_STREAM_DATATYPE(uint32_t val, uint32_t >> stream_id) >> { >> - return ((val) << >> DSI_COMMAND_COMPRESSION_MODE_CTRL_STREAM0_DATATYPE__SHIFT) & >> DSI_COMMAND_COMPRESSION_MODE_CTRL_STREAM0_DATATYPE__MASK; >> + return ((val) << >> (DSI_COMMAND_COMPRESSION_MODE_CTRL_STREAM0_DATATYPE__SHIFT + (stream_id >> * 16)) & DSI_COMMAND_COMPRESSION_MODE_CTRL_STREAM0_DATATYPE__MASK; >> } >> >> Video mode can also use all of these except for WC as that field is not >> present for cmd modes. >> >> This can go as a separate change . >> >> I can push this and perhaps get a Tested-by from Vinod as I dont have a >> setup to re-validate this. > > How would you represent this in XML? I was hoping for a method that > allows to construct the value in a generic way, without register names, > and then simply have a "register macro" that moves (and perhaps masks) > the preconstructed value into the right place. A bit like how `enum`s > are currently set up in XML, but with bit ranges for the values and > macros to set a value. > > I think I've _partially_ found what I was looking for: a `<bitset>`. > However, I don't know if we can utilize this multiple times within a > single `reg32`, once with an offset for stream1. Alas, it's just > bikeshedding at this point. Unfortunately the following naïve patch doesn't work, stream1 bits are still defined in the 0:15 bit space. One would have to modify rnn tool to make sure that it takes into account the low/high parts of the bitfield when generating offsets/masks. diff --git a/src/freedreno/registers/dsi/dsi.xml b/src/freedreno/registers/dsi/dsi.xml index f2eef4ff41ae..b0166628ad0a 100644 --- a/src/freedreno/registers/dsi/dsi.xml +++ b/src/freedreno/registers/dsi/dsi.xml @@ -361,22 +361,19 @@ xsi:schemaLocation="http://nouveau.freedesktop.org/ rules-ng.xsd"> <bitfield name="MAJOR" low="24" high="31" type="uint"/> </reg32> <reg32 offset="0x002d4" name="CPHY_MODE_CTRL"/> - <reg32 offset="0x0029c" name="VIDEO_COMPRESSION_MODE_CTRL"> - <bitfield name="WC" low="16" high="31" type="uint"/> + <bitset name="COMPRESSION_MODE_CTRL" inline="true"> <bitfield name="DATATYPE" low="8" high="13" type="uint"/> <bitfield name="PKT_PER_LINE" low="6" high="7" type="uint"/> <bitfield name="EOL_BYTE_NUM" low="4" high="5" type="uint"/> <bitfield name="EN" pos="0" type="boolean"/> + </bitset> + <reg32 offset="0x0029c" name="VIDEO_COMPRESSION_MODE_CTRL"> + <bitfield name="WC" low="16" high="31" type="uint"/> + <bitfield name="STREAM0" low="0" high="15" type="COMPRESSION_MODE_CTRL"/> </reg32> <reg32 offset="0x002a4" name="COMMAND_COMPRESSION_MODE_CTRL"> - <bitfield name="STREAM1_DATATYPE" low="24" high="29" type="uint"/> - <bitfield name="STREAM1_PKT_PER_LINE" low="22" high="23" type="uint"/> - <bitfield name="STREAM1_EOL_BYTE_NUM" low="20" high="21" type="uint"/> - <bitfield name="STREAM1_EN" pos="16" type="boolean"/> - <bitfield name="STREAM0_DATATYPE" low="8" high="13" type="uint"/> - <bitfield name="STREAM0_PKT_PER_LINE" low="6" high="7" type="uint"/> - <bitfield name="STREAM0_EOL_BYTE_NUM" low="4" high="5" type="uint"/> - <bitfield name="STREAM0_EN" pos="0" type="boolean"/> + <bitfield name="STREAM1" low="16" high="31" type="COMPRESSION_MODE_CTRL"/> + <bitfield name="STREAM0" low="0" high="15" type="COMPRESSION_MODE_CTRL"/> </reg32> <reg32 offset="0x002a8" name="COMMAND_COMPRESSION_MODE_CTRL2"> <bitfield name="STREAM1_SLICE_WIDTH" low="16" high="31" type="uint"/>
On 2022-05-02 12:41:37, Dmitry Baryshkov wrote: > On 02/05/2022 11:43, Marijn Suijten wrote: > > On 2022-05-02 01:44:20, Dmitry Baryshkov wrote: > >> [sni[ > >>> In any case, given that you've already sent this patch and another three > >>> patches [2] fixing/cleaning up the series tells me it's far from ready. > >>> Most of this should just be handled - or have been handled - in review > >>> and amended? > >> > >> During the review time we agreed that [2] would come as a separate > >> change It is an API change that would make using panel-bridge easier, > >> but isn't otherwise required. > >> > >> I have been working towards more logical drm_bridge/drm_bridge_connector > >> chains employing panel-bridge and display-connector where required, [2] > >> is a part of that effort (as well as few other patches that hit > >> dri-devel in the last few days). > > > > I understand what is going on now. Since the DSC patches have already > > been queued up in the 5.19 pull I won't hurry to review them; rather > > will go over them when time allows me to play with the many phones here > > that require DSC for the screen to work. I've been told the series > > didn't result in positive screen output way back in its infancy, but > > I'll re-evaluate and send fixes or improvements if/when necessary. > > Sure, thank you! > > They work on Pixel3 (sdm845, non-active CTLs, no ping-pong binding to > intf). I still didn't have time to test them on P4 (sm8150, active CTLs, > PPs bound to the intf in runtime). The devices mentioned above were all recent SoCs with active CTLs. My ping-pong binding to intf patch recently "fixed" sm6125 (non-DSC) but I have been told it didn't make a difference on the more powerful SoCs (sm8[123]50) with DSC panels. There might indeed be a problem with either active CTLs and CMDmode in general (we still have patches in the works that move PP features to the INTF block) or DSC + actice CTL, or both. To be continued... - Marijn
On 01-05-22, 22:41, Marijn Suijten wrote: > On 2022-04-30 22:28:42, Dmitry Baryshkov wrote: > > On 30/04/2022 21:58, Marijn Suijten wrote: > > > On 2022-04-30 20:55:33, Dmitry Baryshkov wrote: > > >> The downstream uses read-modify-write for updating command mode > > >> compression registers. Let's follow this approach. This also fixes the > > >> following warning: > > >> > > >> drivers/gpu/drm/msm/dsi/dsi_host.c:918:23: warning: variable 'reg_ctrl' set but not used [-Wunused-but-set-variable] > > >> > > >> Reported-by: kernel test robot <lkp@intel.com> > > >> Fixes: 08802f515c3c ("drm/msm/dsi: Add support for DSC configuration") > > >> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org> > > > > > > I pointed this out in review multiple times, so you'll obviously get my: > > > > I think I might have also pointed this out once (and then forgot to > > check that the issue was fixed by Vinod). > > > > > > > > Reviewed-by: Marijn Suijten <marijn.suijten@somainline.org> > > > > > > (But are you sure there's nothing else to clear in the 1st CTRL > > > register, only the lowest 16 bits? That should mean `reg` never > > > contains anything in 0xffff0000) > > > > Judging from the downstream the upper half conains the same fields, but > > used for other virtual channel. I didn't research what's the difference > > yet. All the dtsi files that I have here at hand use > > 'qcom,mdss-dsi-virtual-channel-id = <0>;' > > As replied to Abhinav I'm simply asking whether we should be strict > and add `reg & 0xffff` to prevent accidentally writing the top 16 bits, > which are stream 1. It doesn't seem like the current code can hit that > though, with all the macros using masks internally already; but it's Since the macros were used I skipped setting that up explictly... > still a little scary since we're assuming the registers for VIDEO are > identical to CMD (as mentioned in the reply to Abhinav: I wonder if it's The documentation seems to indicate they are similar and that is the reason, I merged the code paths and set different registers required for video and cmd modes
diff --git a/drivers/gpu/drm/msm/dsi/dsi_host.c b/drivers/gpu/drm/msm/dsi/dsi_host.c index c983698d1384..a95d5df52653 100644 --- a/drivers/gpu/drm/msm/dsi/dsi_host.c +++ b/drivers/gpu/drm/msm/dsi/dsi_host.c @@ -961,10 +961,13 @@ static void dsi_update_dsc_timing(struct msm_dsi_host *msm_host, bool is_cmd_mod reg_ctrl = dsi_read(msm_host, REG_DSI_COMMAND_COMPRESSION_MODE_CTRL); reg_ctrl2 = dsi_read(msm_host, REG_DSI_COMMAND_COMPRESSION_MODE_CTRL2); + reg_ctrl &= ~0xffff; reg_ctrl |= reg; + + reg_ctrl2 &= ~DSI_COMMAND_COMPRESSION_MODE_CTRL2_STREAM0_SLICE_WIDTH__MASK; reg_ctrl2 |= DSI_COMMAND_COMPRESSION_MODE_CTRL2_STREAM0_SLICE_WIDTH(bytes_in_slice); - dsi_write(msm_host, REG_DSI_COMMAND_COMPRESSION_MODE_CTRL, reg); + dsi_write(msm_host, REG_DSI_COMMAND_COMPRESSION_MODE_CTRL, reg_ctrl); dsi_write(msm_host, REG_DSI_COMMAND_COMPRESSION_MODE_CTRL2, reg_ctrl2); } else { dsi_write(msm_host, REG_DSI_VIDEO_COMPRESSION_MODE_CTRL, reg);
The downstream uses read-modify-write for updating command mode compression registers. Let's follow this approach. This also fixes the following warning: drivers/gpu/drm/msm/dsi/dsi_host.c:918:23: warning: variable 'reg_ctrl' set but not used [-Wunused-but-set-variable] Reported-by: kernel test robot <lkp@intel.com> Fixes: 08802f515c3c ("drm/msm/dsi: Add support for DSC configuration") Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org> --- Changes since v1: - Fix c&p error and apply mask clear to reg_ctrl2 instead of reg_ctrl (Abhinav) --- drivers/gpu/drm/msm/dsi/dsi_host.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)