Messages in this thread | | | Date | Fri, 13 May 2022 01:16:58 +0300 | Subject | Re: [PATCH v4] drm/msm/dsi: don't powerup at modeset time for parade-ps8640 | From | Dmitry Baryshkov <> |
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On 13/05/2022 01:00, Douglas Anderson wrote: > Commit 7d8e9a90509f ("drm/msm/dsi: move DSI host powerup to modeset > time") caused sc7180 Chromebooks that use the parade-ps8640 bridge > chip to fail to turn the display back on after it turns off. > > Unfortunately, it doesn't look easy to fix the parade-ps8640 driver to > handle the new power sequence. The Linux driver has almost nothing in > it and most of the logic for this bridge chip is in black-box firmware > that the bridge chip uses. > > Also unfortunately, reverting the patch will break "tc358762". > > The long term solution here is probably Dave Stevenson's series [1] > that would give more flexibility. However, that is likely not a quick > fix. > > For the short term, we'll look at the compatible of the next bridge in > the chain and go back to the old way for the Parade PS8640 bridge > chip. If it's found that other bridge chips also need this workaround > then we can add them to the list or consider inverting the condition. > > [1] https://lore.kernel.org/r/cover.1646406653.git.dave.stevenson@raspberrypi.com > > Fixes: 7d8e9a90509f ("drm/msm/dsi: move DSI host powerup to modeset time") > Suggested-by: Rob Clark <robdclark@gmail.com> > Signed-off-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
> --- > Note that, unlike `struct device`, `struct drm_bridge` still has a > `#ifdef` around the `of_node`. The extra stub function in this patch > is to make sure that we can pass COMPILE_TEST, not because I expect > that we'll actually run into real users who are running this driver > without device tree. > > Changes in v4: > - Use the compatible string of the next bridge as per Rob. > > Changes in v3: > - No longer a revert; now a module parameter. > > Changes in v2: > - Remove the mud from my face. > > drivers/gpu/drm/msm/dsi/dsi_manager.c | 26 +++++++++++++++++++++++++- > 1 file changed, 25 insertions(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/msm/dsi/dsi_manager.c b/drivers/gpu/drm/msm/dsi/dsi_manager.c > index 50b987658b1f..2cabba65a8f1 100644 > --- a/drivers/gpu/drm/msm/dsi/dsi_manager.c > +++ b/drivers/gpu/drm/msm/dsi/dsi_manager.c > @@ -34,6 +34,26 @@ static struct msm_dsi_manager msm_dsim_glb; > #define IS_SYNC_NEEDED() (msm_dsim_glb.is_sync_needed) > #define IS_MASTER_DSI_LINK(id) (msm_dsim_glb.master_dsi_link_id == id) > > +#ifdef CONFIG_OF > +static bool dsi_mgr_power_on_early(struct drm_bridge *bridge) > +{ > + struct drm_bridge *next_bridge = drm_bridge_get_next_bridge(bridge); > + > + /* > + * If the next bridge in the chain is the Parade ps8640 bridge chip > + * then don't power on early since it seems to violate the expectations > + * of the firmware that the bridge chip is running. > + */ > + return !(next_bridge && next_bridge->of_node && > + of_device_is_compatible(next_bridge->of_node, "parade,ps8640")); > +} > +#else > +static inline bool dsi_mgr_power_on_early(struct drm_bridge *bridge) > +{ > + return true; > +} > +#endif > + > static inline struct msm_dsi *dsi_mgr_get_dsi(int id) > { > return msm_dsim_glb.dsi[id]; > @@ -389,6 +409,9 @@ static void dsi_mgr_bridge_pre_enable(struct drm_bridge *bridge) > if (is_bonded_dsi && !IS_MASTER_DSI_LINK(id)) > return; > > + if (!dsi_mgr_power_on_early(bridge)) > + dsi_mgr_bridge_power_on(bridge); > + > /* Always call panel functions once, because even for dual panels, > * there is only one drm_panel instance. > */ > @@ -570,7 +593,8 @@ static void dsi_mgr_bridge_mode_set(struct drm_bridge *bridge, > if (is_bonded_dsi && other_dsi) > msm_dsi_host_set_display_mode(other_dsi->host, adjusted_mode); > > - dsi_mgr_bridge_power_on(bridge); > + if (dsi_mgr_power_on_early(bridge)) > + dsi_mgr_bridge_power_on(bridge); > } > > static enum drm_mode_status dsi_mgr_bridge_mode_valid(struct drm_bridge *bridge,
-- With best wishes Dmitry
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