diff options
| author | Matt Roper <matthew.d.roper@intel.com> | 2023-10-19 10:02:42 -0700 |
|---|---|---|
| committer | Matt Roper <matthew.d.roper@intel.com> | 2023-10-24 12:21:22 -0700 |
| commit | 8fa1c7cd1fe9cdfc426a603e1f1eecd3f463c487 (patch) | |
| tree | a40b2667e58d9ae7cd69b3f8edd2ba7fb47f64fd | |
| parent | a1c613ae4c322ddd58d5a8539dbfba2a0380a8c0 (diff) | |
drm/i915/mcr: Hold GT forcewake during steering operations
The steering control and semaphore registers are inside an "always on"
power domain with respect to RC6. However there are some issues if
higher-level platform sleep states are entering/exiting at the same time
these registers are accessed. Grabbing GT forcewake and holding it over
the entire lock/steer/unlock cycle ensures that those sleep states have
been fully exited before we access these registers.
This is expected to become a formally documented/numbered workaround
soon.
Note that this patch alone isn't expected to have an immediately
noticeable impact on MCR (mis)behavior; an upcoming pcode firmware
update will also be necessary to provide the other half of this
workaround.
v2:
- Move the forcewake inside the Xe_LPG-specific IP version check. This
should only be necessary on platforms that have a steering semaphore.
Fixes: 3100240bf846 ("drm/i915/mtl: Add hardware-level lock for steering")
Cc: Radhakrishna Sripada <radhakrishna.sripada@intel.com>
Cc: Jonathan Cavitt <jonathan.cavitt@intel.com>
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Reviewed-by: Radhakrishna Sripada <radhakrishna.sripada@intel.com>
Reviewed-by: Jonathan Cavitt <jonathan.cavitt@intel.com>
Reviewed-by: Andi Shyti <andi.shyti@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231019170241.2102037-2-matthew.d.roper@intel.com
| -rw-r--r-- | drivers/gpu/drm/i915/gt/intel_gt_mcr.c | 24 |
1 files changed, 22 insertions, 2 deletions
diff --git a/drivers/gpu/drm/i915/gt/intel_gt_mcr.c b/drivers/gpu/drm/i915/gt/intel_gt_mcr.c index 326c2ed1d99b..34913912d8ae 100644 --- a/drivers/gpu/drm/i915/gt/intel_gt_mcr.c +++ b/drivers/gpu/drm/i915/gt/intel_gt_mcr.c @@ -376,9 +376,26 @@ void intel_gt_mcr_lock(struct intel_gt *gt, unsigned long *flags) * driver threads, but also with hardware/firmware agents. A dedicated * locking register is used. */ - if (GRAPHICS_VER_FULL(gt->i915) >= IP_VER(12, 70)) + if (GRAPHICS_VER_FULL(gt->i915) >= IP_VER(12, 70)) { + /* + * The steering control and semaphore registers are inside an + * "always on" power domain with respect to RC6. However there + * are some issues if higher-level platform sleep states are + * entering/exiting at the same time these registers are + * accessed. Grabbing GT forcewake and holding it over the + * entire lock/steer/unlock cycle ensures that those sleep + * states have been fully exited before we access these + * registers. This wakeref will be released in the unlock + * routine. + * + * This is expected to become a formally documented/numbered + * workaround soon. + */ + intel_uncore_forcewake_get(gt->uncore, FORCEWAKE_GT); + err = wait_for(intel_uncore_read_fw(gt->uncore, MTL_STEER_SEMAPHORE) == 0x1, 100); + } /* * Even on platforms with a hardware lock, we'll continue to grab @@ -415,8 +432,11 @@ void intel_gt_mcr_unlock(struct intel_gt *gt, unsigned long flags) { spin_unlock_irqrestore(>->mcr_lock, flags); - if (GRAPHICS_VER_FULL(gt->i915) >= IP_VER(12, 70)) + if (GRAPHICS_VER_FULL(gt->i915) >= IP_VER(12, 70)) { intel_uncore_write_fw(gt->uncore, MTL_STEER_SEMAPHORE, 0x1); + + intel_uncore_forcewake_put(gt->uncore, FORCEWAKE_GT); + } } /** |