Re: [RFC PATCH 3/4] drm/panfrost: Support ARM_64_LPAE_S1 page table

[Boris Brezillon <boris.brezillon@collabora.com>]

On Wed, 26 Feb 2025 15:30:42 -0300
Ariel D'Alessandro <ariel.dalessandro@collabora.com> wrote:

> @@ -642,8 +713,15 @@ struct panfrost_mmu *panfrost_mmu_ctx_create(struct panfrost_device *pfdev)
>  		.iommu_dev	= pfdev->dev,
>  	};
>  
> -	mmu->pgtbl_ops = alloc_io_pgtable_ops(ARM_MALI_LPAE, &mmu->pgtbl_cfg,
> -					      mmu);
> +	if (panfrost_has_hw_feature(pfdev, HW_FEATURE_AARCH64_MMU)) {
> +		fmt = ARM_64_LPAE_S1;
> +		mmu->enable = mmu_lpae_s1_enable;
> +	} else {
> +		fmt = ARM_MALI_LPAE;
> +		mmu->enable = mmu_mali_lpae_enable;
> +	}

How about we stick to the legacy pgtable format for all currently
supported GPUs, and make this an opt-in property attached to the
compatible. This way, we can progressively move away from the legacy
format once enough testing has been done, while allowing support for
GPUs that can't use the old format because the cachability/shareability
configuration is too limited.