Re: [PATCH v1 4/6] drm/panfrost: Add support for AARCH64_4K page table format
From: AngeloGioacchino Del Regno
Date: Tue Mar 11 2025 - 05:14:55 EST
Il 11/03/25 09:05, Boris Brezillon ha scritto:
On Mon, 10 Mar 2025 16:59:19 -0300
Ariel D'Alessandro <ariel.dalessandro@xxxxxxxxxxxxx> wrote:
Currently, Panfrost only supports MMU configuration in "LEGACY" (as
Bifrost calls it) mode, a (modified) version of LPAE "Large Physical
Address Extension", which in Linux we've called "mali_lpae".
This commit adds support for conditionally enabling AARCH64_4K page
table format. To achieve that, a "GPU optional configurations" field was
added to `struct panfrost_features` with the related flag.
Note that, in order to enable AARCH64_4K mode, the GPU variant must have
the HW_FEATURE_AARCH64_MMU feature flag present.
Signed-off-by: Ariel D'Alessandro <ariel.dalessandro@xxxxxxxxxxxxx>
---
drivers/gpu/drm/panfrost/panfrost_device.h | 16 +++
drivers/gpu/drm/panfrost/panfrost_mmu.c | 132 +++++++++++++++++++--
drivers/gpu/drm/panfrost/panfrost_regs.h | 34 ++++++
3 files changed, 169 insertions(+), 13 deletions(-)
diff --git a/drivers/gpu/drm/panfrost/panfrost_device.h b/drivers/gpu/drm/panfrost/panfrost_device.h
index cffcb0ac7c111..0385702aa43c7 100644
--- a/drivers/gpu/drm/panfrost/panfrost_device.h
+++ b/drivers/gpu/drm/panfrost/panfrost_device.h
@@ -42,6 +42,14 @@ enum panfrost_gpu_pm {
GPU_PM_VREG_OFF,
};
+/**
+ * enum panfrost_gpu_config - GPU optional configurations
+ * @GPU_CONFIG_AARCH64_4K: Use AARCH64_4K page table format
+ */
+enum panfrost_gpu_config {
+ GPU_CONFIG_AARCH64_4K,
+};
+
struct panfrost_features {
u16 id;
u16 revision;
@@ -95,6 +103,9 @@ struct panfrost_compatible {
/* Allowed PM features */
u8 pm_features;
+
+ /* GPU features */
+ u8 gpu_configs;
I would probably name this gpu_quirks, with the GPU_CONFIG_AARCH64_4K
flag renamed GPU_QUIRK_FORCE_AARCH64_PAGE_TABLE.
Boris, at this point the quirk should be LPAE, not AARCH64_4K, because the
former is legacy...
I think that Ariel is right in this, as in, that's a capability of the GPU
MMU, so if anything I would rather rename it to gpu_capabilities, but then
that'd be confusing for other stuff - which means that gpu_configs is most
probably the least confusing and/or most appropriate name for this.
Of course, just IMO.
Cheers,
Angelo
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