[PATCH] [media] v4l: rcar-fcp: Don't force users to check for disabled FCP support

[PATCH] [media] v4l: rcar-fcp: Don't force users to check for disabled FCP support

[Laurent Pinchart]

commit fd44aa9a254b18176ec3792a18e7de6977030ca8 upstream.

The rcar_fcp_enable() function immediately returns successfully when the
FCP device pointer is NULL to avoid forcing the users to check the FCP
device manually before every call. However, the stub version of the
function used when the FCP driver is disabled returns -ENOSYS
unconditionally, resulting in a different API contract for the two
versions of the function.

As a user that requires FCP support will fail at probe time when calling
rcar_fcp_get() if the FCP driver is disabled, the stub version of the
rcar_fcp_enable() function will only be called with a NULL FCP device.
We can thus return 0 unconditionally to align the behaviour with the
normal version of the function.

Fixes: 94fcdf829793 ("[media] v4l: vsp1: Add FCP support")
Reported-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
---
 include/media/rcar-fcp.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/media/rcar-fcp.h b/include/media/rcar-fcp.h
index 4c7fc77eaf29..8723f05c6321 100644
--- a/include/media/rcar-fcp.h
+++ b/include/media/rcar-fcp.h
@@ -29,7 +29,7 @@ static inline struct rcar_fcp_device *rcar_fcp_get(const struct device_node *np)
 static inline void rcar_fcp_put(struct rcar_fcp_device *fcp) { }
 static inline int rcar_fcp_enable(struct rcar_fcp_device *fcp)
 {
-	return -ENOSYS;
+	return 0;
 }
 static inline void rcar_fcp_disable(struct rcar_fcp_device *fcp) { }
 #endif
-- 
Regards,

Laurent Pinchart

Re: [PATCH] [media] v4l: rcar-fcp: Don't force users to check for disabled FCP support

[Greg KH]

On Tue, Oct 18, 2016 at 04:24:20PM +0300, Laurent Pinchart wrote:
> commit fd44aa9a254b18176ec3792a18e7de6977030ca8 upstream.
> 
> The rcar_fcp_enable() function immediately returns successfully when the
> FCP device pointer is NULL to avoid forcing the users to check the FCP
> device manually before every call. However, the stub version of the
> function used when the FCP driver is disabled returns -ENOSYS
> unconditionally, resulting in a different API contract for the two
> versions of the function.
> 
> As a user that requires FCP support will fail at probe time when calling
> rcar_fcp_get() if the FCP driver is disabled, the stub version of the
> rcar_fcp_enable() function will only be called with a NULL FCP device.
> We can thus return 0 unconditionally to align the behaviour with the
> normal version of the function.
> 
> Fixes: 94fcdf829793 ("[media] v4l: vsp1: Add FCP support")
> Reported-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
> Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
> Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
> Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
> ---
>  include/media/rcar-fcp.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)

What stable kernel(s) do you want this applied to?

thanks,

greg k-h

Re: [PATCH] [media] v4l: rcar-fcp: Don't force users to check for disabled FCP support

[Laurent Pinchart]

Hi Greg,

On Tuesday 18 Oct 2016 16:05:21 Greg KH wrote:
> On Tue, Oct 18, 2016 at 04:24:20PM +0300, Laurent Pinchart wrote:
> > commit fd44aa9a254b18176ec3792a18e7de6977030ca8 upstream.
> > 
> > The rcar_fcp_enable() function immediately returns successfully when the
> > FCP device pointer is NULL to avoid forcing the users to check the FCP
> > device manually before every call. However, the stub version of the
> > function used when the FCP driver is disabled returns -ENOSYS
> > unconditionally, resulting in a different API contract for the two
> > versions of the function.
> > 
> > As a user that requires FCP support will fail at probe time when calling
> > rcar_fcp_get() if the FCP driver is disabled, the stub version of the
> > rcar_fcp_enable() function will only be called with a NULL FCP device.
> > We can thus return 0 unconditionally to align the behaviour with the
> > normal version of the function.
> > 
> > Fixes: 94fcdf829793 ("[media] v4l: vsp1: Add FCP support")
> > Reported-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
> > Signed-off-by: Laurent Pinchart
> > <laurent.pinchart+renesas@ideasonboard.com>
> > Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
> > Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
> > ---
> > 
> >  include/media/rcar-fcp.h | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> What stable kernel(s) do you want this applied to?

That's for v4.8, sorry for not having mentioned it.

-- 
Regards,

Laurent Pinchart