[Freedreno] [PATCH v2 1/5] drm/msm/dpu: check both DPU and MDSS devices for the IOMMU

[Abhinav Kumar]

On 5/4/2022 5:16 PM, Dmitry Baryshkov wrote:
> Follow the lead of MDP5 driver and check both DPU and MDSS devices for
> the IOMMU specifiers.
> 
> Historically DPU devices had IOMMU specified in the MDSS device tree
> node, but as some of MDP5 devices are being converted to the supported
> by the DPU driver, the driver should adapt and check both devices.
> 
> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov at linaro.org>
> ---
>   drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c | 14 +++++++++++---
>   1 file changed, 11 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
> index 143d6643be53..5ccda0766f6c 100644
> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
> @@ -1004,14 +1004,22 @@ static int _dpu_kms_mmu_init(struct dpu_kms *dpu_kms)
>   	struct msm_mmu *mmu;
>   	struct device *dpu_dev = dpu_kms->dev->dev;
>   	struct device *mdss_dev = dpu_dev->parent;
> +	struct device *iommu_dev;
>   
>   	domain = iommu_domain_alloc(&platform_bus_type);
>   	if (!domain)
>   		return 0;
>   
> -	/* IOMMUs are a part of MDSS device tree binding, not the
> -	 * MDP/DPU device. */
> -	mmu = msm_iommu_new(mdss_dev, domain);
> +	/*
> +	 * IOMMUs can be a part of MDSS device tree binding, or the
> +	 * MDP/DPU device.
> +	 */

Can you please explain this a little more?

So even if some of the mdp5 devices are getting converted to use DPU 
driver, their device trees are also updated right?

In other words, if DPU driver was using mdss_dev to initialize the 
iommu, why should the new devices which are going to use DPU have the 
binding in the dpu_dev?


> +	if (dev_iommu_fwspec_get(dpu_dev))
> +		iommu_dev = dpu_dev;
> +	else
> +		iommu_dev = mdss_dev;
> +
> +	mmu = msm_iommu_new(iommu_dev, domain);
>   	if (IS_ERR(mmu)) {
>   		iommu_domain_free(domain);
>   		return PTR_ERR(mmu);