Re: [PATCH 2/3] drm/msm: stop supporting no-IOMMU configuration

[Konrad Dybcio]

On 7/6/25 12:50 PM, Dmitry Baryshkov wrote:
> With the switch to GPUVM the msm driver no longer supports the no-IOMMU
> configurations (even without the actual GPU). Return an error in case we
> face the lack of the IOMMU for an MDP4 device.
> 
> Fixes: 111fdd2198e6 ("drm/msm: drm_gpuvm conversion")
> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxxxxxxxx>
> ---
>  drivers/gpu/drm/msm/msm_kms.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/msm/msm_kms.c b/drivers/gpu/drm/msm/msm_kms.c
> index 6889f1c1e72121dcc735fa460ea04cdab11c6705..2e2ab93b0f6f6a462e99d54b33da6dc21b1e8435 100644
> --- a/drivers/gpu/drm/msm/msm_kms.c
> +++ b/drivers/gpu/drm/msm/msm_kms.c
> @@ -201,8 +201,8 @@ struct drm_gpuvm *msm_kms_init_vm(struct drm_device *dev)
>  		return ERR_CAST(mmu);
>  
>  	if (!mmu) {
> -		drm_info(dev, "no IOMMU, fallback to phys contig buffers for scanout\n");
> -		return NULL;
> +		drm_info(dev, "no IOMMU configuration is no longer supported\n");

"Couldn't IOMMU-map buffers, bailing out"?

I don't think we need to assume the user has knowledge of the driver history

Konrad