Re: [PATCH] drm: rcar-du: Make sure DRM planes are created by VSP1

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Jacopo,

On Friday 03 Mar 2017 13:37:56 jacopo mondi wrote:
> On 03/03/2017 12:26, Laurent Pinchart wrote:
> > On Friday 03 Mar 2017 09:09:38 Jacopo Mondi wrote:
> >> On Gen3 platforms compositing planes are allocated  by VSP on behalf of
> >> DRM/KMS. If VSP support is not compiled in, vsp1 initialization stub
> >> routine is called, leading to invalid memory accesses later on when un-
> >> initialized planes are accessed.
> >> 
> >> Fail explicitly earlier if planes are not properly created.
> >> 
> >> Signed-off-by: Jacopo Mondi <jacopo+renesas@jmondi.org>
> >> ---
> >> 
> >>  drivers/gpu/drm/rcar-du/rcar_du_kms.c | 3 +++
> >>  1 file changed, 3 insertions(+)
> >> 
> >> diff --git a/drivers/gpu/drm/rcar-du/rcar_du_kms.c
> >> b/drivers/gpu/drm/rcar-du/rcar_du_kms.c index b5d3f16..7f56c09 100644
> >> --- a/drivers/gpu/drm/rcar-du/rcar_du_kms.c
> >> +++ b/drivers/gpu/drm/rcar-du/rcar_du_kms.c
> >> @@ -616,6 +616,9 @@ int rcar_du_modeset_init(struct rcar_du_device *rcdu)
> >>  			ret = rcar_du_vsp_init(vsp);
> >>  			if (ret < 0)
> >>  				return ret;
> >> +
> >> +			if (!vsp->planes)
> >> +				return -EINVAL;
> > 
> > Given that this code is only called when the DU hardware requires the VSP
> > to operate, how about modifying the rcar_du_vsp_init() stub function to
> > return - ENXIO instead of 0 ? That way you won't need to add an
> > additional check here.
>
> Ok, I'll make sure it is only called there also.
> 
> > Ideally we should require VSP through Kconfig as well. If you feel like
> > submitting a patch (and testing it with various combinations of module and
> > built-in) it would be appreciated.
> 
> That would be ideal.
> Am I wrong or the condition that selects DRM_RCAR_VSP is (DRM_RCAR_DU &&
> Gen3-platform)? Implying that on Gen2 DU can live without VSP enabled?

That's correct. On Gen2 VSP isn't required to operate the display.

> >>  		}
> >>  	
> >>  	}

-- 
Regards,

Laurent Pinchart