On Wed, Apr 20, 2022 at 04:05:35PM +0800, Miaoqian Lin wrote:
>
> On 2022/4/20 15:51, Maxime Ripard wrote:
> > On Wed, Apr 20, 2022 at 12:49:48AM +0000, Miaoqian Lin wrote:
> >> If the device is already in a runtime PM enabled state
> >> pm_runtime_get_sync() will return 1, so a test for negative
> >> value should be used to check for errors.
> >>
> >> Also, we need to call pm_runtime_put_noidle() when pm_runtime_get_sync()
> >> fails, so use pm_runtime_resume_and_get() instead. this function
> >> will handle this.
> >>
> >> Fixes: 4078f5757144 ("drm/vc4: Add DSI driver")
> >> Signed-off-by: Miaoqian Lin <[email protected]>
> >> ---
> >> change in v2:
> >> - switch to pm_runtime_resume_and_get() to fix refcount leak.
> >> ---
> >> drivers/gpu/drm/vc4/vc4_dsi.c | 4 ++--
> >> 1 file changed, 2 insertions(+), 2 deletions(-)
> >>
> >> diff --git a/drivers/gpu/drm/vc4/vc4_dsi.c b/drivers/gpu/drm/vc4/vc4_dsi.c
> >> index 752f921735c6..9d7ffaf6bc70 100644
> >> --- a/drivers/gpu/drm/vc4/vc4_dsi.c
> >> +++ b/drivers/gpu/drm/vc4/vc4_dsi.c
> >> @@ -846,8 +846,8 @@ static void vc4_dsi_encoder_enable(struct drm_encoder *encoder)
> >> unsigned long phy_clock;
> >> int ret;
> >>
> >> - ret = pm_runtime_get_sync(dev);
> >> - if (ret) {
> >> + ret = pm_runtime_resume_and_get(dev);
> >> + if (ret < 0) {
> > pm_runtime_resume_and_get will return 0 on success, so the previous check was correct
>
> previous check is for pm_runtime_get_sync() not for pm_runtime_resume_and_get (),
>
> I switch to pm_runtime_resume_and_get() to fix the refcount leak bug at the same time.
>
> Sure it's ok to use check if(ret) to check the retval, I just follow a more common way
>
> for usage of pm_runtime_resume_and_get() in the codebase—— check ret<0
>
> Since pm_runtime_resume_and_get() return negative error code.
If it ain't broke, don't fix it. The previous condition was working
perfectly fine to catch the errors from pm_runtime_resume_and_get,
there's no reason to change it.
Maxime
If the device is already in a runtime PM enabled state
pm_runtime_get_sync() will return 1.
Also, we need to call pm_runtime_put_noidle() when pm_runtime_get_sync()
fails, so use pm_runtime_resume_and_get() instead. this function
will handle this.
Fixes: 4078f5757144 ("drm/vc4: Add DSI driver")
Signed-off-by: Miaoqian Lin <[email protected]>
---
change in v2:
- switch to pm_runtime_resume_and_get() to fix refcount leak.
changes in v3:
- keep the original checking way for retval.
---
drivers/gpu/drm/vc4/vc4_dsi.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/vc4/vc4_dsi.c b/drivers/gpu/drm/vc4/vc4_dsi.c
index 752f921735c6..98308a17e4ed 100644
--- a/drivers/gpu/drm/vc4/vc4_dsi.c
+++ b/drivers/gpu/drm/vc4/vc4_dsi.c
@@ -846,7 +846,7 @@ static void vc4_dsi_encoder_enable(struct drm_encoder *encoder)
unsigned long phy_clock;
int ret;
- ret = pm_runtime_get_sync(dev);
+ ret = pm_runtime_resume_and_get(dev);
if (ret) {
DRM_ERROR("Failed to runtime PM enable on DSI%d\n", dsi->variant->port);
return;
--
2.17.1