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Message-ID: <20260113-device-support-info-v1-4-91e5db7f7294@imgtec.com>
Date: Tue, 13 Jan 2026 10:16:42 +0000
From: Matt Coster <matt.coster@...tec.com>
To: Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
Maxime Ripard
<mripard@...nel.org>,
Thomas Zimmermann <tzimmermann@...e.de>,
David Airlie
<airlied@...il.com>, Simona Vetter <simona@...ll.ch>
CC: Frank Binns <frank.binns@...tec.com>,
Brajesh Gupta
<brajesh.gupta@...tec.com>,
Alessio Belle <alessio.belle@...tec.com>,
Alexandru Dadu <alexandru.dadu@...tec.com>,
Matt Coster
<matt.coster@...tec.com>,
<dri-devel@...ts.freedesktop.org>, <linux-kernel@...r.kernel.org>
Subject: [PATCH 4/6] drm/imagination: Add gpuid module parameter
From: Alexandru Dadu <alexandru.dadu@...tec.com>
The "gpuid" module parameter is used to override the gpuid read from a
hardware register and is useful for testing the loading of different
firmware (including processing of the firmware header) without having
the hardware to hand.
Signed-off-by: Alexandru Dadu <alexandru.dadu@...tec.com>
Signed-off-by: Matt Coster <matt.coster@...tec.com>
---
drivers/gpu/drm/imagination/pvr_device.c | 117 ++++++++++++++++++++++++++++---
drivers/gpu/drm/imagination/pvr_device.h | 7 +-
2 files changed, 114 insertions(+), 10 deletions(-)
diff --git a/drivers/gpu/drm/imagination/pvr_device.c b/drivers/gpu/drm/imagination/pvr_device.c
index abe8ad1d447ac..db844e4e2e945 100644
--- a/drivers/gpu/drm/imagination/pvr_device.c
+++ b/drivers/gpu/drm/imagination/pvr_device.c
@@ -421,23 +421,21 @@ pvr_request_firmware(struct pvr_device *pvr_dev)
}
/**
- * pvr_load_gpu_id() - Load a PowerVR device's GPU ID (BVNC) from control registers.
+ * pvr_gpuid_decode_reg() - Decode the GPU ID from GPU register
*
- * Sets struct pvr_dev.gpu_id.
+ * Sets the b, v, n, c fields of struct pvr_dev.gpu_id.
*
* @pvr_dev: Target PowerVR device.
+ * @gpu_id: Output to be updated with the GPU ID.
*/
static void
-pvr_load_gpu_id(struct pvr_device *pvr_dev)
+pvr_gpuid_decode_reg(const struct pvr_device *pvr_dev, struct pvr_gpu_id *gpu_id)
{
- struct pvr_gpu_id *gpu_id = &pvr_dev->gpu_id;
- u64 bvnc;
-
/*
* Try reading the BVNC using the newer (cleaner) method first. If the
* B value is zero, fall back to the older method.
*/
- bvnc = pvr_cr_read64(pvr_dev, ROGUE_CR_CORE_ID__PBVNC);
+ u64 bvnc = pvr_cr_read64(pvr_dev, ROGUE_CR_CORE_ID__PBVNC);
gpu_id->b = PVR_CR_FIELD_GET(bvnc, CORE_ID__PBVNC__BRANCH_ID);
if (gpu_id->b != 0) {
@@ -456,6 +454,107 @@ pvr_load_gpu_id(struct pvr_device *pvr_dev)
}
}
+/**
+ * pvr_gpuid_decode_string() - Decode the GPU ID from a module input string
+ *
+ * Sets the b, v, n, c fields of struct pvr_dev.gpu_id.
+ *
+ * @pvr_dev: Target PowerVR device.
+ * @param_bvnc: GPU ID (BVNC) module parameter.
+ * @gpu_id: Output to be updated with the GPU ID.
+ */
+static int
+pvr_gpuid_decode_string(const struct pvr_device *pvr_dev,
+ const char *param_bvnc, struct pvr_gpu_id *gpu_id)
+{
+ const struct drm_device *drm_dev = &pvr_dev->base;
+ char str_cpy[PVR_GPUID_STRING_MAX_LENGTH];
+ char *pos, *tkn;
+ int ret, idx = 0;
+ u16 user_bvnc_u16[4];
+ u8 dot_cnt = 0;
+
+ ret = strscpy(str_cpy, param_bvnc);
+
+ /*
+ * strscpy() should return at least a size 7 for the input to be valid.
+ * Returns -E2BIG for the case when the string is empty or too long.
+ */
+ if (ret < PVR_GPUID_STRING_MIN_LENGTH) {
+ drm_info(drm_dev,
+ "Invalid size of the input GPU ID (BVNC): %s",
+ str_cpy);
+ return -EINVAL;
+ }
+
+ while (*param_bvnc) {
+ if (*param_bvnc == '.')
+ dot_cnt++;
+ param_bvnc++;
+ }
+
+ if (dot_cnt != 3) {
+ drm_info(drm_dev,
+ "Invalid format of the input GPU ID (BVNC): %s",
+ str_cpy);
+ return -EINVAL;
+ }
+
+ pos = str_cpy;
+
+ while ((tkn = strsep(&pos, ".")) != NULL && idx < 4) {
+ /* kstrtou16() will also handle the case of consecutive dots */
+ ret = kstrtou16(tkn, 10, &user_bvnc_u16[idx]);
+ if (ret) {
+ drm_info(drm_dev,
+ "Invalid format of the input GPU ID (BVNC): %s",
+ str_cpy);
+ return -EINVAL;
+ }
+ idx++;
+ }
+
+ gpu_id->b = user_bvnc_u16[0];
+ gpu_id->v = user_bvnc_u16[1];
+ gpu_id->n = user_bvnc_u16[2];
+ gpu_id->c = user_bvnc_u16[3];
+
+ return 0;
+}
+
+static char *pvr_gpuid_override;
+module_param_named(gpuid, pvr_gpuid_override, charp, 0400);
+MODULE_PARM_DESC(gpuid, "GPU ID (BVNC) to be used instead of the value read from hardware.");
+
+/**
+ * pvr_load_gpu_id() - Load a PowerVR device's GPU ID (BVNC) from control
+ * registers or input parameter. The input parameter is processed instead
+ * of the GPU register if provided.
+ *
+ * Sets the arch field of struct pvr_dev.gpu_id.
+ *
+ * @pvr_dev: Target PowerVR device.
+ */
+static int
+pvr_load_gpu_id(struct pvr_device *pvr_dev)
+{
+ struct pvr_gpu_id *gpu_id = &pvr_dev->gpu_id;
+
+ if (!pvr_gpuid_override || !pvr_gpuid_override[0]) {
+ pvr_gpuid_decode_reg(pvr_dev, gpu_id);
+ } else {
+ drm_warn(from_pvr_device(pvr_dev),
+ "Using custom GPU ID (BVNC) provided by the user!");
+
+ int err = pvr_gpuid_decode_string(pvr_dev, pvr_gpuid_override,
+ gpu_id);
+ if (err)
+ return err;
+ }
+
+ return 0;
+}
+
/**
* pvr_set_dma_info() - Set PowerVR device DMA information
* @pvr_dev: Target PowerVR device.
@@ -516,7 +615,9 @@ pvr_device_gpu_init(struct pvr_device *pvr_dev)
{
int err;
- pvr_load_gpu_id(pvr_dev);
+ err = pvr_load_gpu_id(pvr_dev);
+ if (err)
+ return err;
err = pvr_request_firmware(pvr_dev);
if (err)
diff --git a/drivers/gpu/drm/imagination/pvr_device.h b/drivers/gpu/drm/imagination/pvr_device.h
index d0e61923fd9b4..5608a977f6d21 100644
--- a/drivers/gpu/drm/imagination/pvr_device.h
+++ b/drivers/gpu/drm/imagination/pvr_device.h
@@ -39,6 +39,9 @@ struct firmware;
/* Forward declaration from <linux/pwrseq/consumer.h> */
struct pwrseq_desc;
+#define PVR_GPUID_STRING_MIN_LENGTH 7U
+#define PVR_GPUID_STRING_MAX_LENGTH 32U
+
/**
* struct pvr_gpu_id - Hardware GPU ID information for a PowerVR device
* @b: Branch ID.
@@ -558,7 +561,7 @@ pvr_device_has_feature(struct pvr_device *pvr_dev, u32 feature);
* Return: The value of the requested register.
*/
static __always_inline u32
-pvr_cr_read32(struct pvr_device *pvr_dev, u32 reg)
+pvr_cr_read32(const struct pvr_device *pvr_dev, u32 reg)
{
return ioread32(pvr_dev->regs + reg);
}
@@ -571,7 +574,7 @@ pvr_cr_read32(struct pvr_device *pvr_dev, u32 reg)
* Return: The value of the requested register.
*/
static __always_inline u64
-pvr_cr_read64(struct pvr_device *pvr_dev, u32 reg)
+pvr_cr_read64(const struct pvr_device *pvr_dev, u32 reg)
{
return ioread64(pvr_dev->regs + reg);
}
--
2.52.0
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