diff options
| author | Michal Wajdeczko <michal.wajdeczko@intel.com> | 2024-07-02 20:37:04 +0200 |
|---|---|---|
| committer | Michal Wajdeczko <michal.wajdeczko@intel.com> | 2024-07-04 11:55:40 +0200 |
| commit | 3078d9c8b6a0939bc732fd1c36ef86c0178127dd (patch) | |
| tree | 90e5c007abe8ea171ed53a0b764300cf07243fea | |
| parent | 466a6c3855cf00653c14a92a6e9f8ae50077b77d (diff) | |
drm/xe: Use VF_CAP_REG for device wmb
To force a write barrier on the device memory, we write to the
SOFTWARE_FLAGS_SPR33 register, but this particular register was
selected because it was one of the writable and unused register.
Since a write barrier should also work if we use the read-only
register, switch to VF_CAP_REG register that is also marked as
accessible for VFs.
While at it, add simple kernel-doc for xe_device_wmb() function.
Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Cc: Matt Roper <matthew.d.roper@intel.com>
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Reviewed-by: Himal Prasad Ghimiray <himal.prasad.ghimiray@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240702183704.1022-4-michal.wajdeczko@intel.com
| -rw-r--r-- | drivers/gpu/drm/xe/xe_device.c | 11 |
1 files changed, 10 insertions, 1 deletions
diff --git a/drivers/gpu/drm/xe/xe_device.c b/drivers/gpu/drm/xe/xe_device.c index 03492fbcb8fb..db513175b29e 100644 --- a/drivers/gpu/drm/xe/xe_device.c +++ b/drivers/gpu/drm/xe/xe_device.c @@ -744,13 +744,22 @@ void xe_device_shutdown(struct xe_device *xe) { } +/** + * xe_device_wmb() - Device specific write memory barrier + * @xe: the &xe_device + * + * While wmb() is sufficient for a barrier if we use system memory, on discrete + * platforms with device memory we additionally need to issue a register write. + * Since it doesn't matter which register we write to, use the read-only VF_CAP + * register that is also marked as accessible by the VFs. + */ void xe_device_wmb(struct xe_device *xe) { struct xe_gt *gt = xe_root_mmio_gt(xe); wmb(); if (IS_DGFX(xe)) - xe_mmio_write32(gt, SOFTWARE_FLAGS_SPR33, 0); + xe_mmio_write32(gt, VF_CAP_REG, 0); } /** |