[PATCH v2 1/2] drm/imagination: Define packed BVNCs in the uapi
From: Matt Coster
Date: Fri Mar 20 2026 - 11:24:45 EST
Using the uapi-safe __GENMASK_ULL(), we can stably define the layout of
64-bit packed BVNCs. These defs replace the replicated doc comment that
appears all over the place.
Signed-off-by: Matt Coster <matt.coster@xxxxxxxxxx>
---
Changes in v2:
- Add _CONST variant of PVR_PACKED_BVNC() for use in case statements.
This fixes the build issue reported by the test bot[1][2]
- Link to v1: https://patch.msgid.link/20260206-bvnc-cleanup-v1-1-f3c818541fbe@xxxxxxxxxx
[1]: https://lore.kernel.org/r/202602070204.PjaKNSpZ-lkp@xxxxxxxxx/
[2]: https://lore.kernel.org/r/202602070500.zo0DrH6U-lkp@xxxxxxxxx/
---
drivers/gpu/drm/imagination/pvr_device.c | 6 ++---
drivers/gpu/drm/imagination/pvr_device.h | 43 +++++++++++++-------------------
include/uapi/drm/pvr_drm.h | 14 +++++------
3 files changed, 27 insertions(+), 36 deletions(-)
diff --git a/drivers/gpu/drm/imagination/pvr_device.c b/drivers/gpu/drm/imagination/pvr_device.c
index f58bb66a6327..9b26585a42bf 100644
--- a/drivers/gpu/drm/imagination/pvr_device.c
+++ b/drivers/gpu/drm/imagination/pvr_device.c
@@ -547,11 +547,11 @@ static enum pvr_gpu_support_level
pvr_gpu_support_level(const struct pvr_gpu_id *gpu_id)
{
switch (pvr_gpu_id_to_packed_bvnc(gpu_id)) {
- case PVR_PACKED_BVNC(33, 15, 11, 3):
- case PVR_PACKED_BVNC(36, 53, 104, 796):
+ case PVR_PACKED_BVNC_CONST(33, 15, 11, 3):
+ case PVR_PACKED_BVNC_CONST(36, 53, 104, 796):
return PVR_GPU_SUPPORTED;
- case PVR_PACKED_BVNC(36, 52, 104, 182):
+ case PVR_PACKED_BVNC_CONST(36, 52, 104, 182):
return PVR_GPU_EXPERIMENTAL;
default:
diff --git a/drivers/gpu/drm/imagination/pvr_device.h b/drivers/gpu/drm/imagination/pvr_device.h
index d51c57cf9332..55d8ff11d507 100644
--- a/drivers/gpu/drm/imagination/pvr_device.h
+++ b/drivers/gpu/drm/imagination/pvr_device.h
@@ -14,7 +14,7 @@
#include <drm/drm_file.h>
#include <drm/drm_mm.h>
-#include <linux/bits.h>
+#include <linux/bitfield.h>
#include <linux/compiler_attributes.h>
#include <linux/compiler_types.h>
#include <linux/device.h>
@@ -470,6 +470,12 @@ struct pvr_file {
#define to_pvr_file(file) ((file)->driver_priv)
+#define __PVR_PACKED_BVNC(prep, b, v, n, c) \
+ (prep(DRM_PVR_BVNC_B, b) | \
+ prep(DRM_PVR_BVNC_V, v) | \
+ prep(DRM_PVR_BVNC_N, n) | \
+ prep(DRM_PVR_BVNC_C, c))
+
/**
* PVR_PACKED_BVNC() - Packs B, V, N and C values into a 64-bit unsigned integer
* @b: Branch ID.
@@ -477,39 +483,24 @@ struct pvr_file {
* @n: Number of scalable units.
* @c: Config ID.
*
- * The packed layout is as follows:
- *
- * +--------+--------+--------+-------+
- * | 63..48 | 47..32 | 31..16 | 15..0 |
- * +========+========+========+=======+
- * | B | V | N | C |
- * +--------+--------+--------+-------+
+ * The packed layout follows the bitfield defined by the DRM_PVR_BVNC_* macros.
*
* pvr_gpu_id_to_packed_bvnc() should be used instead of this macro when a
* &struct pvr_gpu_id is available in order to ensure proper type checking.
*
* Return: Packed BVNC.
*/
-/* clang-format off */
-#define PVR_PACKED_BVNC(b, v, n, c) \
- ((((u64)(b) & GENMASK_ULL(15, 0)) << 48) | \
- (((u64)(v) & GENMASK_ULL(15, 0)) << 32) | \
- (((u64)(n) & GENMASK_ULL(15, 0)) << 16) | \
- (((u64)(c) & GENMASK_ULL(15, 0)) << 0))
-/* clang-format on */
+#define PVR_PACKED_BVNC(b, v, n, c) __PVR_PACKED_BVNC(FIELD_PREP, b, v, n, c)
+
+/** PVR_PACKED_BVNC_CONST() - Compile-time equivalent of PVR_PACKED_BVNC(). */
+#define PVR_PACKED_BVNC_CONST(b, v, n, c) __PVR_PACKED_BVNC(FIELD_PREP_CONST, b, v, n, c)
/**
* pvr_gpu_id_to_packed_bvnc() - Packs B, V, N and C values into a 64-bit
* unsigned integer
* @gpu_id: GPU ID.
*
- * The packed layout is as follows:
- *
- * +--------+--------+--------+-------+
- * | 63..48 | 47..32 | 31..16 | 15..0 |
- * +========+========+========+=======+
- * | B | V | N | C |
- * +--------+--------+--------+-------+
+ * The packed layout follows the bitfield defined by the DRM_PVR_BVNC_* macros.
*
* This should be used in preference to PVR_PACKED_BVNC() when a &struct
* pvr_gpu_id is available in order to ensure proper type checking.
@@ -525,10 +516,10 @@ pvr_gpu_id_to_packed_bvnc(const struct pvr_gpu_id *gpu_id)
static __always_inline void
packed_bvnc_to_pvr_gpu_id(u64 bvnc, struct pvr_gpu_id *gpu_id)
{
- gpu_id->b = (bvnc & GENMASK_ULL(63, 48)) >> 48;
- gpu_id->v = (bvnc & GENMASK_ULL(47, 32)) >> 32;
- gpu_id->n = (bvnc & GENMASK_ULL(31, 16)) >> 16;
- gpu_id->c = bvnc & GENMASK_ULL(15, 0);
+ gpu_id->b = FIELD_GET(DRM_PVR_BVNC_B, bvnc);
+ gpu_id->v = FIELD_GET(DRM_PVR_BVNC_V, bvnc);
+ gpu_id->n = FIELD_GET(DRM_PVR_BVNC_N, bvnc);
+ gpu_id->c = FIELD_GET(DRM_PVR_BVNC_C, bvnc);
}
int pvr_device_init(struct pvr_device *pvr_dev);
diff --git a/include/uapi/drm/pvr_drm.h b/include/uapi/drm/pvr_drm.h
index ccf6c2112468..72f3f90560cf 100644
--- a/include/uapi/drm/pvr_drm.h
+++ b/include/uapi/drm/pvr_drm.h
@@ -6,6 +6,7 @@
#include "drm.h"
+#include <linux/bits.h>
#include <linux/const.h>
#include <linux/types.h>
@@ -113,6 +114,11 @@ struct drm_pvr_obj_array {
* DOC: PowerVR IOCTL DEV_QUERY interface
*/
+#define DRM_PVR_BVNC_B __GENMASK_ULL(63, 48)
+#define DRM_PVR_BVNC_V __GENMASK_ULL(47, 32)
+#define DRM_PVR_BVNC_N __GENMASK_ULL(31, 16)
+#define DRM_PVR_BVNC_C __GENMASK_ULL(15, 0)
+
/**
* struct drm_pvr_dev_query_gpu_info - Container used to fetch information about
* the graphics processor.
@@ -125,13 +131,7 @@ struct drm_pvr_dev_query_gpu_info {
* @gpu_id: GPU identifier.
*
* For all currently supported GPUs this is the BVNC encoded as a 64-bit
- * value as follows:
- *
- * +--------+--------+--------+-------+
- * | 63..48 | 47..32 | 31..16 | 15..0 |
- * +========+========+========+=======+
- * | B | V | N | C |
- * +--------+--------+--------+-------+
+ * value using the DRM_PVR_BVNC_* bitmasks.
*/
__u64 gpu_id;
--
2.53.0