Re: [PATCH] drm/rockchip: Check iommu itself instead of it's parent for device_is_available

[Andy Yan]

Hi Robin:

On 6/28/21 5:54 PM, Robin Murphy wrote:
> On 2021-06-27 09:47, Andy Yan wrote:
> > When iommu itself is disabled in dts, we should
> > fallback to non-iommu buffer, check iommu parent
> > is meanless here.
> >
> > Signed-off-by: Andy Yan <andy.yan@xxxxxxxxxxxxxx>
> > ---
> >
> >   drivers/gpu/drm/rockchip/rockchip_drm_drv.c | 2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_drv.c 
> > b/drivers/gpu/drm/rockchip/rockchip_drm_drv.c
> > index 212bd87c0c4a..0d20c8cc1ffa 100644
> > --- a/drivers/gpu/drm/rockchip/rockchip_drm_drv.c
> > +++ b/drivers/gpu/drm/rockchip/rockchip_drm_drv.c
> > @@ -366,7 +366,7 @@ static int rockchip_drm_platform_of_probe(struct 
> > device *dev)
> >           }
> >             iommu = of_parse_phandle(port->parent, "iommus", 0);
> > -        if (!iommu || !of_device_is_available(iommu->parent)) {
> > +        if (!iommu || !of_device_is_available(iommu)) {
>
> Just wondering, could you use device_iommu_mapped() to avoid poking at 
> the DT at all here, or is it that you need to check remote graph 
> endpoints whose struct device may not be ready yet?


device_iommu_mapped(dev)  can't be called from rockchip_drm_init_iommu, 
as there is no  iommu dev(vop) in these function.

> Robin.
>
> >               DRM_DEV_DEBUG(dev,
> >                         "no iommu attached for %pOF, using non-iommu 
> > buffers\n",
> >                         port->parent);