Minki/linux
1
0
Fork 1
mirror of https://github.com/torvalds/linux.git synced 2024-11-10 06:01:57 +00:00
Code Issues Packages Projects Releases Wiki Activity

drm/xe: Use VF_CAP_REG for device wmb

Browse Source 
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
This commit is contained in:
Michal Wajdeczko 2024-07-02 20:37:04 +02:00
parent 466a6c3855
commit 3078d9c8b6
1 changed files with 10 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

11
drivers/gpu/drm/xe/xe_device.c
View File

@ -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);
}
/**