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

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Message-ID: <20250314173858.212264-6-ariel.dalessandro@collabora.com>
Date: Fri, 14 Mar 2025 14:38:57 -0300
From: Ariel D'Alessandro <ariel.dalessandro@...labora.com>
To: dri-devel@...ts.freedesktop.org,
	linux-kernel@...r.kernel.org
Cc: boris.brezillon@...labora.com,
	robh@...nel.org,
	steven.price@....com,
	maarten.lankhorst@...ux.intel.com,
	mripard@...nel.org,
	tzimmermann@...e.de,
	airlied@...il.com,
	simona@...ll.ch,
	kernel@...labora.com,
	linux-mediatek@...ts.infradead.org,
	linux-arm-kernel@...ts.infradead.org,
	sjoerd@...labora.com,
	angelogioacchino.delregno@...labora.com,
	Ariel D'Alessandro <ariel.dalessandro@...labora.com>
Subject: [PATCH v2 5/6] drm/panfrost: Force AARCH64_4K page table format on MediaTek MT8188

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@...labora.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.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 };
-- 
2.47.2