drm/xe/pf: Clamp maximum execution quantum to 100s

GuC is silently clamping values of the execution quantum and
preemption timeout KLVs to 100s. Perform explicit clamping on the
driver side as later there is no way to read back values used by
the firmware and we shouldn't mislead the user about actual values
being used when we print them in dmesg or debugfs.

Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Reviewed-by: Piotr Piórkowski <piotr.piorkowski@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240419123543.270-3-michal.wajdeczko@intel.com

diff --git a/drivers/gpu/drm/xe/xe_gt_sriov_pf_config.c b/drivers/gpu/drm/xe/xe_gt_sriov_pf_config.c
index 79116ad..7eac01e 100644 (file)
--- a/drivers/gpu/drm/xe/xe_gt_sriov_pf_config.c
+++ b/drivers/gpu/drm/xe/xe_gt_sriov_pf_config.c
@@ -187,14 +187,20 @@ static int pf_push_vf_cfg_dbs(struct xe_gt *gt, unsigned int vfid, u32 begin, u3
        return pf_push_vf_cfg_klvs(gt, vfid, 2, klvs, ARRAY_SIZE(klvs));
 }
 
-static int pf_push_vf_cfg_exec_quantum(struct xe_gt *gt, unsigned int vfid, u32 exec_quantum)
+static int pf_push_vf_cfg_exec_quantum(struct xe_gt *gt, unsigned int vfid, u32 *exec_quantum)
 {
-       return pf_push_vf_cfg_u32(gt, vfid, GUC_KLV_VF_CFG_EXEC_QUANTUM_KEY, exec_quantum);
+       /* GuC will silently clamp values exceeding max */
+       *exec_quantum = min_t(u32, *exec_quantum, GUC_KLV_VF_CFG_EXEC_QUANTUM_MAX_VALUE);
+
+       return pf_push_vf_cfg_u32(gt, vfid, GUC_KLV_VF_CFG_EXEC_QUANTUM_KEY, *exec_quantum);
 }
 
-static int pf_push_vf_cfg_preempt_timeout(struct xe_gt *gt, unsigned int vfid, u32 preempt_timeout)
+static int pf_push_vf_cfg_preempt_timeout(struct xe_gt *gt, unsigned int vfid, u32 *preempt_timeout)
 {
-       return pf_push_vf_cfg_u32(gt, vfid, GUC_KLV_VF_CFG_PREEMPT_TIMEOUT_KEY, preempt_timeout);
+       /* GuC will silently clamp values exceeding max */
+       *preempt_timeout = min_t(u32, *preempt_timeout, GUC_KLV_VF_CFG_PREEMPT_TIMEOUT_MAX_VALUE);
+
+       return pf_push_vf_cfg_u32(gt, vfid, GUC_KLV_VF_CFG_PREEMPT_TIMEOUT_KEY, *preempt_timeout);
 }
 
 static int pf_push_vf_cfg_lmem(struct xe_gt *gt, unsigned int vfid, u64 size)
@@ -1604,7 +1610,7 @@ static int pf_provision_exec_quantum(struct xe_gt *gt, unsigned int vfid,
        struct xe_gt_sriov_config *config = pf_pick_vf_config(gt, vfid);
        int err;
 
-       err = pf_push_vf_cfg_exec_quantum(gt, vfid, exec_quantum);
+       err = pf_push_vf_cfg_exec_quantum(gt, vfid, &exec_quantum);
        if (unlikely(err))
                return err;
 
@@ -1674,7 +1680,7 @@ static int pf_provision_preempt_timeout(struct xe_gt *gt, unsigned int vfid,
        struct xe_gt_sriov_config *config = pf_pick_vf_config(gt, vfid);
        int err;
 
-       err = pf_push_vf_cfg_preempt_timeout(gt, vfid, preempt_timeout);
+       err = pf_push_vf_cfg_preempt_timeout(gt, vfid, &preempt_timeout);
        if (unlikely(err))
                return err;