pm_runtime_get_sync() increments the runtime PM usage counter
even when it returns an error code. However, users of
dsi_runtime_get(), a direct wrapper of pm_runtime_get_sync(),
assume that PM usage counter will not change on error. Thus a
pairing decrement is needed on the error handling path to keep
the counter balanced.
Fixes: 4fbafaf371be7 ("OMAP: DSS2: Use PM runtime & HWMOD support")
Signed-off-by: Dinghao Liu <[email protected]>
---
drivers/gpu/drm/omapdrm/dss/dsi.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/omapdrm/dss/dsi.c b/drivers/gpu/drm/omapdrm/dss/dsi.c
index eeccf40bae41..973bfa14a104 100644
--- a/drivers/gpu/drm/omapdrm/dss/dsi.c
+++ b/drivers/gpu/drm/omapdrm/dss/dsi.c
@@ -1112,8 +1112,11 @@ static int dsi_runtime_get(struct dsi_data *dsi)
DSSDBG("dsi_runtime_get\n");
r = pm_runtime_get_sync(dsi->dev);
- WARN_ON(r < 0);
- return r < 0 ? r : 0;
+ if (WARN_ON(r < 0)) {
+ pm_runtime_put_noidle(dsi->dev);
+ return r;
+ }
+ return 0;
}
static void dsi_runtime_put(struct dsi_data *dsi)
--
2.17.1
Hi,
On 21/08/2020 10:45, Dinghao Liu wrote:
> pm_runtime_get_sync() increments the runtime PM usage counter
> even when it returns an error code. However, users of
> dsi_runtime_get(), a direct wrapper of pm_runtime_get_sync(),
> assume that PM usage counter will not change on error. Thus a
> pairing decrement is needed on the error handling path to keep
> the counter balanced.
>
> Fixes: 4fbafaf371be7 ("OMAP: DSS2: Use PM runtime & HWMOD support")
> Signed-off-by: Dinghao Liu <[email protected]>
> ---
> drivers/gpu/drm/omapdrm/dss/dsi.c | 7 +++++--
> 1 file changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/omapdrm/dss/dsi.c b/drivers/gpu/drm/omapdrm/dss/dsi.c
> index eeccf40bae41..973bfa14a104 100644
> --- a/drivers/gpu/drm/omapdrm/dss/dsi.c
> +++ b/drivers/gpu/drm/omapdrm/dss/dsi.c
> @@ -1112,8 +1112,11 @@ static int dsi_runtime_get(struct dsi_data *dsi)
> DSSDBG("dsi_runtime_get\n");
>
> r = pm_runtime_get_sync(dsi->dev);
> - WARN_ON(r < 0);
> - return r < 0 ? r : 0;
> + if (WARN_ON(r < 0)) {
> + pm_runtime_put_noidle(dsi->dev);
> + return r;
> + }
> + return 0;
> }
Thanks! Good catch. I think this is broken in all the other modules in omapdrm too (e.g. dispc.c,
venc.c, etc).
Would you like to update the patch to cover the whole omapdrm?
Tomi
--
Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki.
Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki
> Hi,
>
> On 21/08/2020 10:45, Dinghao Liu wrote:
> > pm_runtime_get_sync() increments the runtime PM usage counter
> > even when it returns an error code. However, users of
> > dsi_runtime_get(), a direct wrapper of pm_runtime_get_sync(),
> > assume that PM usage counter will not change on error. Thus a
> > pairing decrement is needed on the error handling path to keep
> > the counter balanced.
> >
> > Fixes: 4fbafaf371be7 ("OMAP: DSS2: Use PM runtime & HWMOD support")
> > Signed-off-by: Dinghao Liu <[email protected]>
> > ---
> > drivers/gpu/drm/omapdrm/dss/dsi.c | 7 +++++--
> > 1 file changed, 5 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/omapdrm/dss/dsi.c b/drivers/gpu/drm/omapdrm/dss/dsi.c
> > index eeccf40bae41..973bfa14a104 100644
> > --- a/drivers/gpu/drm/omapdrm/dss/dsi.c
> > +++ b/drivers/gpu/drm/omapdrm/dss/dsi.c
> > @@ -1112,8 +1112,11 @@ static int dsi_runtime_get(struct dsi_data *dsi)
> > DSSDBG("dsi_runtime_get\n");
> >
> > r = pm_runtime_get_sync(dsi->dev);
> > - WARN_ON(r < 0);
> > - return r < 0 ? r : 0;
> > + if (WARN_ON(r < 0)) {
> > + pm_runtime_put_noidle(dsi->dev);
> > + return r;
> > + }
> > + return 0;
> > }
>
> Thanks! Good catch. I think this is broken in all the other modules in omapdrm too (e.g. dispc.c,
> venc.c, etc).
>
> Would you like to update the patch to cover the whole omapdrm?
>
Sure. I will fix this soon.
Regards,
Dinghao
Hi Tomi,
On Fri, Aug 21, 2020 at 03:06:59PM +0300, Tomi Valkeinen wrote:
> On 21/08/2020 10:45, Dinghao Liu wrote:
> > pm_runtime_get_sync() increments the runtime PM usage counter
> > even when it returns an error code. However, users of
> > dsi_runtime_get(), a direct wrapper of pm_runtime_get_sync(),
> > assume that PM usage counter will not change on error. Thus a
> > pairing decrement is needed on the error handling path to keep
> > the counter balanced.
> >
> > Fixes: 4fbafaf371be7 ("OMAP: DSS2: Use PM runtime & HWMOD support")
> > Signed-off-by: Dinghao Liu <[email protected]>
> > ---
> > drivers/gpu/drm/omapdrm/dss/dsi.c | 7 +++++--
> > 1 file changed, 5 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/omapdrm/dss/dsi.c b/drivers/gpu/drm/omapdrm/dss/dsi.c
> > index eeccf40bae41..973bfa14a104 100644
> > --- a/drivers/gpu/drm/omapdrm/dss/dsi.c
> > +++ b/drivers/gpu/drm/omapdrm/dss/dsi.c
> > @@ -1112,8 +1112,11 @@ static int dsi_runtime_get(struct dsi_data *dsi)
> > DSSDBG("dsi_runtime_get\n");
> >
> > r = pm_runtime_get_sync(dsi->dev);
> > - WARN_ON(r < 0);
> > - return r < 0 ? r : 0;
> > + if (WARN_ON(r < 0)) {
> > + pm_runtime_put_noidle(dsi->dev);
> > + return r;
> > + }
> > + return 0;
> > }
>
> Thanks! Good catch. I think this is broken in all the other modules in omapdrm too (e.g. dispc.c,
> venc.c, etc).
>
> Would you like to update the patch to cover the whole omapdrm?
Just for yoru information, there has been quite a few similar patches
submitted all across the kernel. I believe this is an issue of the
pm_runtime_get_sync() API, which really shouldn't require a put() when
it fails. For drivers that really don't expect pm_runtime_get_sync() to
fail (no I2C access to a regulator for instance, only SoC-internal
operations) I've instead decided to ignore the error completely. I don't
think poluting the whole kernel code base with this kind of "fixes" is a
good idea.
--
Regards,
Laurent Pinchart