[RFC PATCH 04/18] drm/panthor: Add 64-bit GPU_ID decoding for v15 GPUs
From: Karunika Choo
Date: Thu May 28 2026 - 11:24:46 EST
Mali v15 exposes a 64-bit GPU_ID register with a different field layout
from earlier GPUs.
Add the register definitions and decoding helpers for the new format,
read GPU_WIDE_ID when the compatibility value indicates a v15 GPU, and
populate both the cached GPU_ID fields and the uAPI gpu_id_hi field.
This allows userspace and the driver to identify v15 GPUs correctly.
Signed-off-by: Karunika Choo <karunika.choo@xxxxxxx>
---
.../drm/panthor/panthor_gpu_discover_regs.h | 17 +++++++++
drivers/gpu/drm/panthor/panthor_hw.c | 38 ++++++++++++++-----
include/uapi/drm/panthor_drm.h | 10 +++++
3 files changed, 56 insertions(+), 9 deletions(-)
create mode 100644 drivers/gpu/drm/panthor/panthor_gpu_discover_regs.h
diff --git a/drivers/gpu/drm/panthor/panthor_gpu_discover_regs.h b/drivers/gpu/drm/panthor/panthor_gpu_discover_regs.h
new file mode 100644
index 000000000000..54bb104902ee
--- /dev/null
+++ b/drivers/gpu/drm/panthor/panthor_gpu_discover_regs.h
@@ -0,0 +1,17 @@
+/* SPDX-License-Identifier: GPL-2.0 or MIT */
+/* Copyright 2026 ARM Limited. All rights reserved. */
+
+#ifndef __PANTHOR_GPU_DISCOVER_REGS_H__
+#define __PANTHOR_GPU_DISCOVER_REGS_H__
+
+#define GPU_WIDE_ID 0x0
+#define GPU_WIDE_COMPAT 0xF
+#define GPU_WIDE_ARCH_MAJOR(x) (((x) & GENMASK(63, 56)) >> 56)
+#define GPU_WIDE_ARCH_MINOR(x) (((x) & GENMASK(55, 48)) >> 48)
+#define GPU_WIDE_ARCH_REV(x) (((x) & GENMASK(47, 40)) >> 40)
+#define GPU_WIDE_PROD_MAJOR(x) (((x) & GENMASK(39, 32)) >> 32)
+#define GPU_WIDE_VER_MAJOR(x) (((x) & GENMASK(23, 16)) >> 16)
+#define GPU_WIDE_VER_MINOR(x) (((x) & GENMASK(15, 8)) >> 8)
+#define GPU_WIDE_VER_STATUS(x) ((x) & GENMASK(7, 0))
+
+#endif /* __PANTHOR_GPU_DISCOVER_REGS_H__ */
diff --git a/drivers/gpu/drm/panthor/panthor_hw.c b/drivers/gpu/drm/panthor/panthor_hw.c
index 3570e2889584..833d10cbb2d6 100644
--- a/drivers/gpu/drm/panthor/panthor_hw.c
+++ b/drivers/gpu/drm/panthor/panthor_hw.c
@@ -9,6 +9,7 @@
#include "panthor_device.h"
#include "panthor_device_io.h"
#include "panthor_gpu.h"
+#include "panthor_gpu_discover_regs.h"
#include "panthor_gpu_regs.h"
#include "panthor_hw.h"
#include "panthor_pwr.h"
@@ -297,18 +298,37 @@ static int panthor_hw_bind_device(struct panthor_device *ptdev)
static int panthor_hw_gpu_id_init(struct panthor_device *ptdev)
{
struct panthor_gpu_id *gpu_id = &ptdev->gpu_id;
- ptdev->gpu_info.gpu_id = gpu_read(ptdev->iomem, GPU_ID);
+ u32 gpu_id32 = gpu_read(ptdev->iomem, GPU_ID);
- if (!ptdev->gpu_info.gpu_id)
+ if (!gpu_id32)
return -ENXIO;
- gpu_id->arch.major = GPU_ARCH_MAJOR(ptdev->gpu_info.gpu_id);
- gpu_id->arch.minor = GPU_ARCH_MINOR(ptdev->gpu_info.gpu_id);
- gpu_id->arch.rev = GPU_ARCH_REV(ptdev->gpu_info.gpu_id);
- gpu_id->prod_major = GPU_PROD_MAJOR(ptdev->gpu_info.gpu_id);
- gpu_id->ver.major = GPU_VER_MAJOR(ptdev->gpu_info.gpu_id);
- gpu_id->ver.minor = GPU_VER_MINOR(ptdev->gpu_info.gpu_id);
- gpu_id->ver.status = GPU_VER_STATUS(ptdev->gpu_info.gpu_id);
+ ptdev->gpu_info.gpu_id = gpu_id32;
+
+ gpu_id->arch.major = GPU_ARCH_MAJOR(gpu_id32);
+ gpu_id->arch.minor = GPU_ARCH_MINOR(gpu_id32);
+ gpu_id->arch.rev = GPU_ARCH_REV(gpu_id32);
+ gpu_id->prod_major = GPU_PROD_MAJOR(gpu_id32);
+ gpu_id->ver.major = GPU_VER_MAJOR(gpu_id32);
+ gpu_id->ver.minor = GPU_VER_MINOR(gpu_id32);
+ gpu_id->ver.status = GPU_VER_STATUS(gpu_id32);
+
+ if (GPU_ARCH_MAJOR(gpu_id32) == GPU_WIDE_COMPAT) {
+ u64 gpu_id64 = gpu_read64(ptdev->iomem, GPU_WIDE_ID);
+ if (!gpu_id64)
+ return -ENXIO;
+
+ ptdev->gpu_info.gpu_wide_id = gpu_id64;
+ ptdev->gpu_info.gpu_id = 0;
+
+ gpu_id->arch.major = GPU_WIDE_ARCH_MAJOR(gpu_id64);
+ gpu_id->arch.minor = GPU_WIDE_ARCH_MINOR(gpu_id64);
+ gpu_id->arch.rev = GPU_WIDE_ARCH_REV(gpu_id64);
+ gpu_id->prod_major = GPU_WIDE_PROD_MAJOR(gpu_id64);
+ gpu_id->ver.major = GPU_WIDE_VER_MAJOR(gpu_id64);
+ gpu_id->ver.minor = GPU_WIDE_VER_MINOR(gpu_id64);
+ gpu_id->ver.status = GPU_WIDE_VER_STATUS(gpu_id64);
+ }
return 0;
}
diff --git a/include/uapi/drm/panthor_drm.h b/include/uapi/drm/panthor_drm.h
index 0e455d91e77d..04fc9f133152 100644
--- a/include/uapi/drm/panthor_drm.h
+++ b/include/uapi/drm/panthor_drm.h
@@ -373,6 +373,16 @@ struct drm_panthor_gpu_info {
/** @gpu_features: Bitmask describing supported GPU-wide features */
__u64 gpu_features;
+
+ /** @gpu_wide_id: 64-bit GPU_ID for v15 onwards. */
+ __u64 gpu_wide_id;
+#define DRM_PANTHOR_WIDE_ARCH_MAJOR(x) (((x) >> 56) & 0xff)
+#define DRM_PANTHOR_WIDE_ARCH_MINOR(x) (((x) >> 48) & 0xff)
+#define DRM_PANTHOR_WIDE_ARCH_REV(x) (((x) >> 40) & 0xff)
+#define DRM_PANTHOR_WIDE_PRODUCT_MAJOR(x) (((x) >> 32) & 0xff)
+#define DRM_PANTHOR_WIDE_VERSION_MAJOR(x) (((x) >> 16) & 0xff)
+#define DRM_PANTHOR_WIDE_VERSION_MINOR(x) (((x) >> 8) & 0xff)
+#define DRM_PANTHOR_WIDE_VERSION_STATUS(x) ((x) & 0xff)
};
/**
--
2.43.0