[PATCH v2] drm/imx: imx-ldb: Accept drm_of_find_panel_or_bridge failure

[PATCH v2] drm/imx: imx-ldb: Accept drm_of_find_panel_or_bridge failure

[Leonard Crestez]

Not having an endpoint bound in DT should not cause a failure here,
there are fallbacks. So explicitly accept a missing endpoint.

This behavior change was introduced by refactoring in drm_of parsing
code and it should not require dts changes.

In particular this fixes imx6qdl-sabreauto boards.

Link: https://lists.freedesktop.org/archives/dri-devel/2017-May/141233.html
Fixes: ebc944613567 ("drm: convert drivers to use drm_of_find_panel_or_bridge")
Signed-off-by: Leonard Crestez <leonard.crestez@nxp.com>

---

This relies on drm_of_find_panel_or_bridge returning -ENODEV
specifically if no remote is found for the endpoint. This behavior can
be seen by looking at the code but is not otherwise obviously
guaranteed.

Perhaps this should be explicitly mentioned in that function's
documentation?

Changes since v1:
* Fix returning if ret is 0.

 drivers/gpu/drm/imx/imx-ldb.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/imx/imx-ldb.c b/drivers/gpu/drm/imx/imx-ldb.c
index 8fb801f..8b05ecb 100644
--- a/drivers/gpu/drm/imx/imx-ldb.c
+++ b/drivers/gpu/drm/imx/imx-ldb.c
@@ -673,7 +673,7 @@ static int imx_ldb_bind(struct device *dev, struct device *master, void *data)
 		ret = drm_of_find_panel_or_bridge(child,
 						  imx_ldb->lvds_mux ? 4 : 2, 0,
 						  &channel->panel, &channel->bridge);
-		if (ret)
+		if (ret && ret != -ENODEV)
 			return ret;
 
 		/* panel ddc only if there is no bridge */
-- 
2.7.4

Re: [PATCH v2] drm/imx: imx-ldb: Accept drm_of_find_panel_or_bridge failure

[Philipp Zabel]

On Wed, 2017-05-10 at 16:17 +0300, Leonard Crestez wrote:
> Not having an endpoint bound in DT should not cause a failure here,
> there are fallbacks. So explicitly accept a missing endpoint.
> 
> This behavior change was introduced by refactoring in drm_of parsing
> code and it should not require dts changes.
> 
> In particular this fixes imx6qdl-sabreauto boards.
> 
> Link: https://lists.freedesktop.org/archives/dri-devel/2017-May/141233.html
> Fixes: ebc944613567 ("drm: convert drivers to use drm_of_find_panel_or_bridge")
> Signed-off-by: Leonard Crestez <leonard.crestez@nxp.com>
> 
> ---
> 
> This relies on drm_of_find_panel_or_bridge returning -ENODEV
> specifically if no remote is found for the endpoint. This behavior can
> be seen by looking at the code but is not otherwise obviously
> guaranteed.
> 
> Perhaps this should be explicitly mentioned in that function's
> documentation?
> 
> Changes since v1:
> * Fix returning if ret is 0.
> 
>  drivers/gpu/drm/imx/imx-ldb.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/imx/imx-ldb.c b/drivers/gpu/drm/imx/imx-ldb.c
> index 8fb801f..8b05ecb 100644
> --- a/drivers/gpu/drm/imx/imx-ldb.c
> +++ b/drivers/gpu/drm/imx/imx-ldb.c
> @@ -673,7 +673,7 @@ static int imx_ldb_bind(struct device *dev, struct device *master, void *data)
>  		ret = drm_of_find_panel_or_bridge(child,
>  						  imx_ldb->lvds_mux ? 4 : 2, 0,
>  						  &channel->panel, &channel->bridge);
> -		if (ret)
> +		if (ret && ret != -ENODEV)
>  			return ret;
>  
>  		/* panel ddc only if there is no bridge */

Thank you, applied to imx-drm/fixes.

regards
Philipp

Re: [PATCH v2] drm/imx: imx-ldb: Accept drm_of_find_panel_or_bridge failure

[Leonard Crestez]

On Wed, 2017-05-10 at 15:55 +0200, Philipp Zabel wrote:
> On Wed, 2017-05-10 at 16:17 +0300, Leonard Crestez wrote:
> > 
> > Not having an endpoint bound in DT should not cause a failure here,
> > there are fallbacks. So explicitly accept a missing endpoint.
> > 
> > This behavior change was introduced by refactoring in drm_of parsing
> > code and it should not require dts changes.
> > 
> > In particular this fixes imx6qdl-sabreauto boards.
> > 
> > diff --git a/drivers/gpu/drm/imx/imx-ldb.c b/drivers/gpu/drm/imx/imx-ldb.c
> > index 8fb801f..8b05ecb 100644
> > --- a/drivers/gpu/drm/imx/imx-ldb.c
> > +++ b/drivers/gpu/drm/imx/imx-ldb.c
> > @@ -673,7 +673,7 @@ static int imx_ldb_bind(struct device *dev, struct device *master, void *data)
> >  		ret = drm_of_find_panel_or_bridge(child,
> >  						  imx_ldb->lvds_mux ? 4 : 2, 0,
> >  						  &channel->panel, &channel->bridge);
> > -		if (ret)
> > +		if (ret && ret != -ENODEV)
> >  			return ret;
> >  
> >  		/* panel ddc only if there is no bridge */
> Thank you, applied to imx-drm/fixes.
> 
> regards
> Philipp

How are such fixes going to make their way upstream? It's been almost a
month and this patch did not get into either linux-next or
torvalds/master or anywhere other than pza/imx-drm/fixes.

--
Regards,
Leonard