Re: [PATCH v2 5/6] drm/panfrost: Force AARCH64_4K page table format on MediaTek MT8188

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

On Fri, 14 Mar 2025 14:38:57 -0300
Ariel D'Alessandro <ariel.dalessandro@collabora.com> wrote:

> MediaTek MT8188 SoC has an ARM Mali-G57 MC3 GPU (Valhall-JM), which
> constantly faults with the current panfrost support.
> 
> For instance, running `glmark2-es2-drm` benchmark test:
> ```
> [   79.617461] panfrost 13000000.gpu: js fault, js=1, status=JOB_BUS_FAULT, head=0xaadc380, tail=0xaadc380
> [   80.119811] panfrost 13000000.gpu: gpu sched timeout, js=0, config=0x7300, status=0x58, head=0xaaca180, tail=0xaaca180, sched_job=000000002fd03ccc
> [   80.129083] panfrost 13000000.gpu: Unhandled Page fault in AS0 at VA 0x0000000000000000
> [   80.129083] Reason: TODO
> [   80.129083] raw fault status: 0x1C2
> [   80.129083] decoded fault status: SLAVE FAULT
> [   80.129083] exception type 0xC2: TRANSLATION_FAULT_2
> [   80.129083] access type 0x1: EXECUTE
> [   80.129083] source id 0x0
> ```
> 
> Note that current panfrost mode (Mali LPAE - LEGACY) only allows to
> specify write-cache or implementation-defined as the caching policy,
> probably not matching the right configuration. As depicted in the source
> code:
> 
> drivers/iommu/io-pgtable-arm.c:
> ```
> * MEMATTR: Mali has no actual notion of a non-cacheable type, so the
> * best we can do is mimic the out-of-tree driver and hope that the
> * "implementation-defined caching policy" is good enough...
> ```
> 
> Now that Panfrost supports AARCH64_4K page table format, let's enable it
> on Mediatek MT8188 and configure the cache/shareability policies
> properly.
> 
> Signed-off-by: Ariel D'Alessandro <ariel.dalessandro@collabora.com>
> Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>

Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>

> ---
>  drivers/gpu/drm/panfrost/panfrost_drv.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/gpu/drm/panfrost/panfrost_drv.c b/drivers/gpu/drm/panfrost/panfrost_drv.c
> index 0f3935556ac76..e854f290858f9 100644
> --- a/drivers/gpu/drm/panfrost/panfrost_drv.c
> +++ b/drivers/gpu/drm/panfrost/panfrost_drv.c
> @@ -824,6 +824,7 @@ static const struct panfrost_compatible mediatek_mt8188_data = {
>  	.num_pm_domains = ARRAY_SIZE(mediatek_mt8183_pm_domains),
>  	.pm_domain_names = mediatek_mt8183_pm_domains,
>  	.pm_features = BIT(GPU_PM_CLK_DIS) | BIT(GPU_PM_VREG_OFF),
> +	.gpu_quirks = BIT(GPU_QUIRK_FORCE_AARCH64_PGTABLE),
>  };
>  
>  static const char * const mediatek_mt8192_supplies[] = { "mali", NULL };