| Message ID | 20220816064231.60473-1-zhangzekun11@huawei.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [-next] drm/bridge: Add missing clk_disable_unprepare() in analogix_dp_resume() | expand |
On Mon, Aug 15, 2022 at 11:46 PM Zhang Zekun <zhangzekun11@huawei.com> wrote: > > Add the missing clk_disable_unprepare() before return from > analogix_dp_resume() in the error handling case. > > Fixes: 211f276ed3d9 ("drm: bridge: analogix/dp: add panel prepare/unprepare in suspend/resume time") > Signed-off-by: Zhang Zekun <zhangzekun11@huawei.com> Reviewed-by: Brian Norris <briannorris@chromium.org>
Hi, On Mon, Aug 15, 2022 at 11:45 PM Zhang Zekun <zhangzekun11@huawei.com> wrote: > > Add the missing clk_disable_unprepare() before return from > analogix_dp_resume() in the error handling case. > > Fixes: 211f276ed3d9 ("drm: bridge: analogix/dp: add panel prepare/unprepare in suspend/resume time") > Signed-off-by: Zhang Zekun <zhangzekun11@huawei.com> > --- > drivers/gpu/drm/bridge/analogix/analogix_dp_core.c | 1 + > 1 file changed, 1 insertion(+) Reviewed-by: Douglas Anderson <dianders@chromium.org> I'll snooze this and check back in approx 1 week. If someone else hasn't already applied it I'll plan to apply it to drm-misc-fixes. -Doug
On Wed, Aug 17, 2022 at 01:34:13PM -0700, Brian Norris wrote: > On Mon, Aug 15, 2022 at 11:46 PM Zhang Zekun <zhangzekun11@huawei.com> wrote: > > > > Add the missing clk_disable_unprepare() before return from > > analogix_dp_resume() in the error handling case. > > > > Fixes: 211f276ed3d9 ("drm: bridge: analogix/dp: add panel prepare/unprepare in suspend/resume time") > > Signed-off-by: Zhang Zekun <zhangzekun11@huawei.com> > > Reviewed-by: Brian Norris <briannorris@chromium.org> Hmm, actually I'm going to have to retract that now that I've given it some more testing locally. I happen to have a system where I commonly hit this error case, and I'm thinking commit 211f276ed3d9 is actually wrong, and so we shouldn't be "fixing" its error handling -- we should be reverting it. In particular, drm_panel_prepare()/drm_panel_unprepare() are *not* reference-counted APIs, and this is already managed by analogix_dp_bridge_disable(), which is called by the core DRM helpers during suspend. Thus, analogix_dp_suspend()/analogix_dp_resume() is serving to be an unwanted *second* client trying to {un,}prepare the panel. The panel drivers tend to handle this OK to some extent, as they (e.g., panel-edp.c) guard against redundant operations, but *we* don't -- notice that analogix_dp_suspend() ignores drm_panel_unprepare() errors for one. Also, I don't believe device management really handles resume() failures quite right; in the end, this patch ends up un-balancing the clk count on the RK3399 Gru-Bob systems I'm testing. (Side note: every other bridge driver seems to ignore drm_panel_prepare() failures.) It's possible this was correct (or at least, not terribly broken) back when it was written, but then, the DRM core frameworks have evolved since then. Today, I think we do not need to manage the panel state directly in suspend()/resume(). All in all: Nacked-by: Brian Norris <briannorris@chromium.org> Tested-and-failed-by: Brian Norris <briannorris@chromium.org> Now separately, I have to figure out why I'm hitting this error case in the first place...
Hi, On Wed, Aug 17, 2022 at 05:05:25PM -0700, Brian Norris wrote: > Hmm, actually I'm going to have to retract that now that I've given it > some more testing locally. I happen to have a system where I commonly > hit this error case, and I'm thinking commit 211f276ed3d9 is actually > wrong, and so we shouldn't be "fixing" its error handling -- we should > be reverting it. I've submitted that for review here: https://lore.kernel.org/all/20220822180729.1.I8ac5abe3a4c1c6fd5c061686c6e883c22f69022c@changeid/ [PATCH] Revert "drm: bridge: analogix/dp: add panel prepare/unprepare in suspend/resume time" I'd appreciate your review/testing. (NB: I failed to honor the .mailmap for Andrzej Hajda.) > Now separately, I have to figure out why I'm hitting this error case in > the first place... FWIW, I captured the reason in point 3 on the above Revert. The pm_runtime_*() handling in the panel driver fails (-EACCES) because the bridge driver is resuming before the panel. (The DRM suspend/resume helpers handle things in the correct order.) This problem is also resolved by simply reverting. Brian
diff --git a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c index 8aadcc0aa90b..a0fd652547f5 100644 --- a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c +++ b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c @@ -1887,6 +1887,7 @@ int analogix_dp_resume(struct analogix_dp_device *dp) if (dp->plat_data->panel) { if (drm_panel_prepare(dp->plat_data->panel)) { DRM_ERROR("failed to setup the panel\n"); + clk_disable_unprepare(dp->clock); return -EBUSY; } }
Add the missing clk_disable_unprepare() before return from analogix_dp_resume() in the error handling case. Fixes: 211f276ed3d9 ("drm: bridge: analogix/dp: add panel prepare/unprepare in suspend/resume time") Signed-off-by: Zhang Zekun <zhangzekun11@huawei.com> --- drivers/gpu/drm/bridge/analogix/analogix_dp_core.c | 1 + 1 file changed, 1 insertion(+)