Re: [PATCH v2 04/21] drm/exynos: Fix potential unbalanced calls to pm_runtime_put
On Fri, 11 Oct 2019 15:54:53 +0200 Andrzej Hajda wrote: > On 26.08.2019 17:26, Boris Brezillon wrote: > > The encoder->enable() can't report errors and is expected to always > > succeed. If we call pm_runtime_put() in the exynos_dsi_enable() error > > path (as currently done) we'll have unbalanced get/put calls when > > encoder->disable() is called. > > > True I just realized this is actually not the case, because the DSIM_STATE_ENABLED flag is cleared in the error path, and exynos_dsi_disable() bails out early when DSIM_STATE_ENABLED is not set. ___ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel
Re: [PATCH v2 04/21] drm/exynos: Fix potential unbalanced calls to pm_runtime_put
On Sat, 12 Oct 2019 09:15:26 +0200 Sam Ravnborg wrote: > Hi Boris/Andrzej. > > > > > > > > > > > > > Note that -ENOSYS is actually a valid case, it just > > > > means the panel driver does not implement the hook. > > > > > > > > > It would be good then to fix it in panel framework, ie without hook > > > drm_panel_* function should return 0, ENOSYS makes no sense here. > > > > I'm fine with that. Thierry, Sam, any opinion? > > Agreed, I have following patch in my panel patch queue: > > drm/drm_panel: no error when no callback > > The callbacks in drm_panel_funcs are optional, so do not > return an error just because no callback is assigned. > > Signed-off-by: Sam Ravnborg > > If I get time this weekend I will rebase/test and send the > set of patches out. Any progress on that? Can I rebase/send it for you if you don't have time? ___ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel
Re: [PATCH v2 04/21] drm/exynos: Fix potential unbalanced calls to pm_runtime_put
Hi Boris/Andrzej. > > > > > > > > Note that -ENOSYS is actually a valid case, it just > > > means the panel driver does not implement the hook. > > > > > > It would be good then to fix it in panel framework, ie without hook > > drm_panel_* function should return 0, ENOSYS makes no sense here. > > I'm fine with that. Thierry, Sam, any opinion? Agreed, I have following patch in my panel patch queue: drm/drm_panel: no error when no callback The callbacks in drm_panel_funcs are optional, so do not return an error just because no callback is assigned. Signed-off-by: Sam Ravnborg If I get time this weekend I will rebase/test and send the set of patches out. Sam ___ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel
Re: [PATCH v2 04/21] drm/exynos: Fix potential unbalanced calls to pm_runtime_put
On Fri, 11 Oct 2019 15:54:53 +0200
Andrzej Hajda wrote:
> On 26.08.2019 17:26, Boris Brezillon wrote:
> > The encoder->enable() can't report errors and is expected to always
> > succeed. If we call pm_runtime_put() in the exynos_dsi_enable() error
> > path (as currently done) we'll have unbalanced get/put calls when
> > encoder->disable() is called.
>
>
> True
>
>
> >
> > The situation is not ideal since drm_panel_{prepare,enable}() can
> > theoretically return an error (even if in practice I don't think any
> > panel driver does that).
>
>
> So why do you want to fix it at all, if you think return value is always
> 0 :) ?
>
>
> git grep -p -A30 '_prepare' drivers/gpu/drm/panel/ shows that many of
> them can return errors.
Then I was wrong :-).
>
>
> > Putting a WARN_ON() is the best we can do,
> > unfortunately.
>
>
> I guess optimally we should use DRM_MODE_LINK_STATUS_BAD, but I am not
> sure how exactly it should be handled.
You mean call
drm_connector_set_link_status_property(DRM_MODE_LINK_STATUS_BAD) ?
>
>
> > Note that -ENOSYS is actually a valid case, it just
> > means the panel driver does not implement the hook.
>
>
> It would be good then to fix it in panel framework, ie without hook
> drm_panel_* function should return 0, ENOSYS makes no sense here.
I'm fine with that. Thierry, Sam, any opinion?
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Re: [PATCH v2 04/21] drm/exynos: Fix potential unbalanced calls to pm_runtime_put
On 26.08.2019 17:26, Boris Brezillon wrote:
> The encoder->enable() can't report errors and is expected to always
> succeed. If we call pm_runtime_put() in the exynos_dsi_enable() error
> path (as currently done) we'll have unbalanced get/put calls when
> encoder->disable() is called.
True
>
> The situation is not ideal since drm_panel_{prepare,enable}() can
> theoretically return an error (even if in practice I don't think any
> panel driver does that).
So why do you want to fix it at all, if you think return value is always
0 :) ?
git grep -p -A30 '_prepare' drivers/gpu/drm/panel/ shows that many of
them can return errors.
> Putting a WARN_ON() is the best we can do,
> unfortunately.
I guess optimally we should use DRM_MODE_LINK_STATUS_BAD, but I am not
sure how exactly it should be handled.
> Note that -ENOSYS is actually a valid case, it just
> means the panel driver does not implement the hook.
It would be good then to fix it in panel framework, ie without hook
drm_panel_* function should return 0, ENOSYS makes no sense here.
Regards
Andrzej
>
> Signed-off-by: Boris Brezillon
> ---
> Changes in v2:
> * New patch
> ---
> drivers/gpu/drm/exynos/exynos_drm_dsi.c | 14 ++
> 1 file changed, 2 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/gpu/drm/exynos/exynos_drm_dsi.c
> b/drivers/gpu/drm/exynos/exynos_drm_dsi.c
> index 8e655ae1fb0c..c555cecfe1f5 100644
> --- a/drivers/gpu/drm/exynos/exynos_drm_dsi.c
> +++ b/drivers/gpu/drm/exynos/exynos_drm_dsi.c
> @@ -1387,8 +1387,7 @@ static void exynos_dsi_enable(struct drm_encoder
> *encoder)
>
> if (dsi->panel) {
> ret = drm_panel_prepare(dsi->panel);
> - if (ret < 0)
> - goto err_put_sync;
> + WARN_ON(ret && ret != -ENOSYS);
> } else {
> drm_bridge_pre_enable(dsi->out_bridge);
> }
> @@ -1398,22 +1397,13 @@ static void exynos_dsi_enable(struct drm_encoder
> *encoder)
>
> if (dsi->panel) {
> ret = drm_panel_enable(dsi->panel);
> - if (ret < 0)
> - goto err_display_disable;
> + WARN_ON(ret && ret != -ENOSYS);
> } else {
> drm_bridge_enable(dsi->out_bridge);
> }
>
> dsi->state |= DSIM_STATE_VIDOUT_AVAILABLE;
> return;
> -
> -err_display_disable:
> - exynos_dsi_set_display_enable(dsi, false);
> - drm_panel_unprepare(dsi->panel);
> -
> -err_put_sync:
> - dsi->state &= ~DSIM_STATE_ENABLED;
> - pm_runtime_put(dsi->dev);
> }
>
> static void exynos_dsi_disable(struct drm_encoder *encoder)
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Re: [PATCH v2 04/21] drm/exynos: Fix potential unbalanced calls to pm_runtime_put
Hi Inki,
On Mon, 26 Aug 2019 17:26:32 +0200
Boris Brezillon wrote:
> The encoder->enable() can't report errors and is expected to always
> succeed. If we call pm_runtime_put() in the exynos_dsi_enable() error
> path (as currently done) we'll have unbalanced get/put calls when
> encoder->disable() is called.
>
> The situation is not ideal since drm_panel_{prepare,enable}() can
> theoretically return an error (even if in practice I don't think any
> panel driver does that). Putting a WARN_ON() is the best we can do,
> unfortunately. Note that -ENOSYS is actually a valid case, it just
> means the panel driver does not implement the hook.
>
> Signed-off-by: Boris Brezillon
Did you have a chance to look at this patch 4 and 5 of this series? I'd
really like to get those 2 patches merged.
Thanks,
Boris
> ---
> Changes in v2:
> * New patch
> ---
> drivers/gpu/drm/exynos/exynos_drm_dsi.c | 14 ++
> 1 file changed, 2 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/gpu/drm/exynos/exynos_drm_dsi.c
> b/drivers/gpu/drm/exynos/exynos_drm_dsi.c
> index 8e655ae1fb0c..c555cecfe1f5 100644
> --- a/drivers/gpu/drm/exynos/exynos_drm_dsi.c
> +++ b/drivers/gpu/drm/exynos/exynos_drm_dsi.c
> @@ -1387,8 +1387,7 @@ static void exynos_dsi_enable(struct drm_encoder
> *encoder)
>
> if (dsi->panel) {
> ret = drm_panel_prepare(dsi->panel);
> - if (ret < 0)
> - goto err_put_sync;
> + WARN_ON(ret && ret != -ENOSYS);
> } else {
> drm_bridge_pre_enable(dsi->out_bridge);
> }
> @@ -1398,22 +1397,13 @@ static void exynos_dsi_enable(struct drm_encoder
> *encoder)
>
> if (dsi->panel) {
> ret = drm_panel_enable(dsi->panel);
> - if (ret < 0)
> - goto err_display_disable;
> + WARN_ON(ret && ret != -ENOSYS);
> } else {
> drm_bridge_enable(dsi->out_bridge);
> }
>
> dsi->state |= DSIM_STATE_VIDOUT_AVAILABLE;
> return;
> -
> -err_display_disable:
> - exynos_dsi_set_display_enable(dsi, false);
> - drm_panel_unprepare(dsi->panel);
> -
> -err_put_sync:
> - dsi->state &= ~DSIM_STATE_ENABLED;
> - pm_runtime_put(dsi->dev);
> }
>
> static void exynos_dsi_disable(struct drm_encoder *encoder)
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[PATCH v2 04/21] drm/exynos: Fix potential unbalanced calls to pm_runtime_put
The encoder->enable() can't report errors and is expected to always
succeed. If we call pm_runtime_put() in the exynos_dsi_enable() error
path (as currently done) we'll have unbalanced get/put calls when
encoder->disable() is called.
The situation is not ideal since drm_panel_{prepare,enable}() can
theoretically return an error (even if in practice I don't think any
panel driver does that). Putting a WARN_ON() is the best we can do,
unfortunately. Note that -ENOSYS is actually a valid case, it just
means the panel driver does not implement the hook.
Signed-off-by: Boris Brezillon
---
Changes in v2:
* New patch
---
drivers/gpu/drm/exynos/exynos_drm_dsi.c | 14 ++
1 file changed, 2 insertions(+), 12 deletions(-)
diff --git a/drivers/gpu/drm/exynos/exynos_drm_dsi.c
b/drivers/gpu/drm/exynos/exynos_drm_dsi.c
index 8e655ae1fb0c..c555cecfe1f5 100644
--- a/drivers/gpu/drm/exynos/exynos_drm_dsi.c
+++ b/drivers/gpu/drm/exynos/exynos_drm_dsi.c
@@ -1387,8 +1387,7 @@ static void exynos_dsi_enable(struct drm_encoder *encoder)
if (dsi->panel) {
ret = drm_panel_prepare(dsi->panel);
- if (ret < 0)
- goto err_put_sync;
+ WARN_ON(ret && ret != -ENOSYS);
} else {
drm_bridge_pre_enable(dsi->out_bridge);
}
@@ -1398,22 +1397,13 @@ static void exynos_dsi_enable(struct drm_encoder
*encoder)
if (dsi->panel) {
ret = drm_panel_enable(dsi->panel);
- if (ret < 0)
- goto err_display_disable;
+ WARN_ON(ret && ret != -ENOSYS);
} else {
drm_bridge_enable(dsi->out_bridge);
}
dsi->state |= DSIM_STATE_VIDOUT_AVAILABLE;
return;
-
-err_display_disable:
- exynos_dsi_set_display_enable(dsi, false);
- drm_panel_unprepare(dsi->panel);
-
-err_put_sync:
- dsi->state &= ~DSIM_STATE_ENABLED;
- pm_runtime_put(dsi->dev);
}
static void exynos_dsi_disable(struct drm_encoder *encoder)
--
2.21.0
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