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[v4,00/24] drm/bridge: Make panel and bridge probe order consistent

Message ID 20210910101218.1632297-1-maxime@cerno.tech
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Series drm/bridge: Make panel and bridge probe order consistent | expand

Message

Maxime Ripard Sept. 10, 2021, 10:11 a.m. UTC
Hi,

We've encountered an issue with the RaspberryPi DSI panel that prevented the
whole display driver from probing.

The issue is described in detail in the commit 7213246a803f ("drm/vc4: dsi:
Only register our component once a DSI device is attached"), but the basic idea
is that since the panel is probed through i2c, there's no synchronization
between its probe and the registration of the MIPI-DSI host it's attached to.

We initially moved the component framework registration to the MIPI-DSI Host
attach hook to make sure we register our component only when we have a DSI
device attached to our MIPI-DSI host, and then use lookup our DSI device in our
bind hook.

However, all the DSI bridges controlled through i2c are only registering their
associated DSI device in their bridge attach hook, meaning with our change
above, we never got that far, and therefore ended up in the same situation than
the one we were trying to fix for panels.

The best practice to avoid those issues is to register its functions only after
all its dependencies are live. We also shouldn't wait any longer than we should
to play nice with the other components that are waiting for us, so in our case
that would mean moving the DSI device registration to the bridge probe.

I also had a look at all the DSI hosts, and it seems that exynos, kirin and msm
would be affected by this and wouldn't probe anymore after those changes.
Exynos and kirin seems to be simple enough for a mechanical change (that still
requires to be tested), but the changes in msm seemed to be far more important
and I wasn't confortable doing them.

Let me know what you think,
Maxime

---

Changes from v3:
  - Converted exynos and kirin
  - Converted all the affected bridge drivers
  - Reworded the documentation a bit

Changes from v2:
  - Changed the approach as suggested by Andrzej, and aligned the bridge on the
    panel this time.
  - Fixed some typos

Changes from v1:
  - Change the name of drm_of_get_next function to drm_of_get_bridge
  - Mention the revert of 87154ff86bf6 and squash the two patches that were
    reverting that commit
  - Add some documentation
  - Make drm_panel_attach and _detach succeed when no callback is there

Maxime Ripard (24):
  drm/bridge: Add documentation sections
  drm/bridge: Document the probe issue with MIPI-DSI bridges
  drm/mipi-dsi: Create devm device registration
  drm/mipi-dsi: Create devm device attachment
  drm/bridge: adv7533: Switch to devm MIPI-DSI helpers
  drm/bridge: adv7511: Register and attach our DSI device at probe
  drm/bridge: anx7625: Switch to devm MIPI-DSI helpers
  drm/bridge: anx7625: Register and attach our DSI device at probe
  drm/bridge: lt8912b: Switch to devm MIPI-DSI helpers
  drm/bridge: lt8912b: Register and attach our DSI device at probe
  drm/bridge: lt9611: Switch to devm MIPI-DSI helpers
  drm/bridge: lt9611: Register and attach our DSI device at probe
  drm/bridge: lt9611uxc: Switch to devm MIPI-DSI helpers
  drm/bridge: lt9611uxc: Register and attach our DSI device at probe
  drm/bridge: ps8640: Switch to devm MIPI-DSI helpers
  drm/bridge: ps8640: Register and attach our DSI device at probe
  drm/bridge: sn65dsi83: Switch to devm MIPI-DSI helpers
  drm/bridge: sn65dsi83: Register and attach our DSI device at probe
  drm/bridge: sn65dsi86: Switch to devm MIPI-DSI helpers
  drm/bridge: sn65dsi86: Register and attach our DSI device at probe
  drm/bridge: tc358775: Switch to devm MIPI-DSI helpers
  drm/bridge: tc358775: Register and attach our DSI device at probe
  drm/kirin: dsi: Adjust probe order
  drm/exynos: dsi: Adjust probe order

 Documentation/gpu/drm-kms-helpers.rst        |  12 +++
 drivers/gpu/drm/bridge/adv7511/adv7511.h     |   1 -
 drivers/gpu/drm/bridge/adv7511/adv7511_drv.c |  15 ++-
 drivers/gpu/drm/bridge/adv7511/adv7533.c     |  20 +---
 drivers/gpu/drm/bridge/analogix/anx7625.c    |  40 ++++----
 drivers/gpu/drm/bridge/lontium-lt8912b.c     |  31 ++----
 drivers/gpu/drm/bridge/lontium-lt9611.c      |  62 +++++-------
 drivers/gpu/drm/bridge/lontium-lt9611uxc.c   |  65 +++++-------
 drivers/gpu/drm/bridge/parade-ps8640.c       | 101 ++++++++++---------
 drivers/gpu/drm/bridge/tc358775.c            |  50 +++++----
 drivers/gpu/drm/bridge/ti-sn65dsi83.c        |  86 ++++++++--------
 drivers/gpu/drm/bridge/ti-sn65dsi86.c        |  94 ++++++++---------
 drivers/gpu/drm/drm_bridge.c                 |  69 ++++++++++++-
 drivers/gpu/drm/drm_mipi_dsi.c               |  81 +++++++++++++++
 drivers/gpu/drm/exynos/exynos_drm_dsi.c      |  19 ++--
 drivers/gpu/drm/hisilicon/kirin/dw_drm_dsi.c |  27 +++--
 include/drm/drm_mipi_dsi.h                   |   4 +
 17 files changed, 460 insertions(+), 317 deletions(-)

-- 
2.31.1

Comments

John Stultz Sept. 29, 2021, 9:32 p.m. UTC | #1
On Wed, Sep 29, 2021 at 2:27 PM John Stultz <john.stultz@linaro.org> wrote:
>

> On Fri, Sep 10, 2021 at 3:12 AM Maxime Ripard <maxime@cerno.tech> wrote:

> >

> > We've encountered an issue with the RaspberryPi DSI panel that prevented the

> > whole display driver from probing.

> >

> > The issue is described in detail in the commit 7213246a803f ("drm/vc4: dsi:

> > Only register our component once a DSI device is attached"), but the basic idea

> > is that since the panel is probed through i2c, there's no synchronization

> > between its probe and the registration of the MIPI-DSI host it's attached to.

> >

> > We initially moved the component framework registration to the MIPI-DSI Host

> > attach hook to make sure we register our component only when we have a DSI

> > device attached to our MIPI-DSI host, and then use lookup our DSI device in our

> > bind hook.

> >

> > However, all the DSI bridges controlled through i2c are only registering their

> > associated DSI device in their bridge attach hook, meaning with our change

> > above, we never got that far, and therefore ended up in the same situation than

> > the one we were trying to fix for panels.

> >

> > The best practice to avoid those issues is to register its functions only after

> > all its dependencies are live. We also shouldn't wait any longer than we should

> > to play nice with the other components that are waiting for us, so in our case

> > that would mean moving the DSI device registration to the bridge probe.

> >

> > I also had a look at all the DSI hosts, and it seems that exynos, kirin and msm

> > would be affected by this and wouldn't probe anymore after those changes.

> > Exynos and kirin seems to be simple enough for a mechanical change (that still

> > requires to be tested), but the changes in msm seemed to be far more important

> > and I wasn't confortable doing them.

>

>

> Hey Maxime,

>   Sorry for taking so long to get to this, but now that plumbers is

> over I've had a chance to check it out on kirin

>

> Rob Clark pointed me to his branch with some fixups here:

>    https://gitlab.freedesktop.org/robclark/msm/-/commits/for-mripard/bridge-rework

>

> But trying to boot hikey with that, I see the following loop indefinitely:

> [    4.632132] adv7511 2-0039: supply avdd not found, using dummy regulator

> [    4.638961] adv7511 2-0039: supply dvdd not found, using dummy regulator

> [    4.645741] adv7511 2-0039: supply pvdd not found, using dummy regulator

> [    4.652483] adv7511 2-0039: supply a2vdd not found, using dummy regulator

> [    4.659342] adv7511 2-0039: supply v3p3 not found, using dummy regulator

> [    4.666086] adv7511 2-0039: supply v1p2 not found, using dummy regulator

> [    4.681898] adv7511 2-0039: failed to find dsi host


I just realized Rob's tree is missing the kirin patch. My apologies!
I'll retest and let you know.

thanks
-john
John Stultz Sept. 29, 2021, 11:29 p.m. UTC | #2
On Wed, Sep 29, 2021 at 2:51 PM John Stultz <john.stultz@linaro.org> wrote:
>

> On Wed, Sep 29, 2021 at 2:32 PM John Stultz <john.stultz@linaro.org> wrote:

> > On Wed, Sep 29, 2021 at 2:27 PM John Stultz <john.stultz@linaro.org> wrote:

> > > On Fri, Sep 10, 2021 at 3:12 AM Maxime Ripard <maxime@cerno.tech> wrote:

> > > > The best practice to avoid those issues is to register its functions only after

> > > > all its dependencies are live. We also shouldn't wait any longer than we should

> > > > to play nice with the other components that are waiting for us, so in our case

> > > > that would mean moving the DSI device registration to the bridge probe.

> > > >

> > > > I also had a look at all the DSI hosts, and it seems that exynos, kirin and msm

> > > > would be affected by this and wouldn't probe anymore after those changes.

> > > > Exynos and kirin seems to be simple enough for a mechanical change (that still

> > > > requires to be tested), but the changes in msm seemed to be far more important

> > > > and I wasn't confortable doing them.

> > >

> > >

> > > Hey Maxime,

> > >   Sorry for taking so long to get to this, but now that plumbers is

> > > over I've had a chance to check it out on kirin

> > >

> > > Rob Clark pointed me to his branch with some fixups here:

> > >    https://gitlab.freedesktop.org/robclark/msm/-/commits/for-mripard/bridge-rework

> > >

> > > But trying to boot hikey with that, I see the following loop indefinitely:

> > > [    4.632132] adv7511 2-0039: supply avdd not found, using dummy regulator

> > > [    4.638961] adv7511 2-0039: supply dvdd not found, using dummy regulator

> > > [    4.645741] adv7511 2-0039: supply pvdd not found, using dummy regulator

> > > [    4.652483] adv7511 2-0039: supply a2vdd not found, using dummy regulator

> > > [    4.659342] adv7511 2-0039: supply v3p3 not found, using dummy regulator

> > > [    4.666086] adv7511 2-0039: supply v1p2 not found, using dummy regulator

> > > [    4.681898] adv7511 2-0039: failed to find dsi host

> >

> > I just realized Rob's tree is missing the kirin patch. My apologies!

> > I'll retest and let you know.

>

> Ok, just retested including the kirin patch and unfortunately I'm

> still seeing the same thing.  :(

>

> Will dig a bit and let you know when I find more.


Hey Maxime!
  I chased down the issue. The dsi probe code was still calling
drm_of_find_panel_or_bridge() in order to succeed.

I've moved the logic that looks for the bridge into the bridge_init
and with that it seems to work.

Feel free (assuming it looks ok) to fold this change into your kirin patch:
  https://git.linaro.org/people/john.stultz/android-dev.git/commit/?id=4a35ccc4d7a53f68d6d93da3b47e232a7c75b91d

thanks
-john