drm/i915/debugfs: Add perf_limit_reasons in debugfs

Add perf_limit_reasons in debugfs. The upper 16 perf_limit_reasons RW "log"
bits are identical to the lower 16 RO "status" bits except that the "log"
bits remain set until cleared, thereby ensuring the throttling occurrence
is not missed. The clear fop clears the upper 16 "log" bits, the get fop
gets all 32 "log" and "status" bits.

v2: Expand commit message and clarify "log" and "status" bits in
    comment (Rodrigo)

Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Ashutosh Dixit <ashutosh.dixit@intel.com>
Signed-off-by: Tilak Tangudu <tilak.tangudu@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220910143844.1755324-2-ashutosh.dixit@intel.com

diff --git a/drivers/gpu/drm/i915/gt/intel_gt_pm_debugfs.c b/drivers/gpu/drm/i915/gt/intel_gt_pm_debugfs.c
index 40bdd4cb629feadcd70506d0de871582b688c7b4..88814f2b32c85ba18202131a5c6f4f96188ba6ed 100644 (file)
--- a/drivers/gpu/drm/i915/gt/intel_gt_pm_debugfs.c
+++ b/drivers/gpu/drm/i915/gt/intel_gt_pm_debugfs.c
@@ -655,6 +655,36 @@ static bool rps_eval(void *data)
 
 DEFINE_INTEL_GT_DEBUGFS_ATTRIBUTE(rps_boost);
 
+static int perf_limit_reasons_get(void *data, u64 *val)
+{
+       struct intel_gt *gt = data;
+       intel_wakeref_t wakeref;
+
+       with_intel_runtime_pm(gt->uncore->rpm, wakeref)
+               *val = intel_uncore_read(gt->uncore, GT0_PERF_LIMIT_REASONS);
+
+       return 0;
+}
+
+static int perf_limit_reasons_clear(void *data, u64 val)
+{
+       struct intel_gt *gt = data;
+       intel_wakeref_t wakeref;
+
+       /*
+        * Clear the upper 16 "log" bits, the lower 16 "status" bits are
+        * read-only. The upper 16 "log" bits are identical to the lower 16
+        * "status" bits except that the "log" bits remain set until cleared.
+        */
+       with_intel_runtime_pm(gt->uncore->rpm, wakeref)
+               intel_uncore_rmw(gt->uncore, GT0_PERF_LIMIT_REASONS,
+                                GT0_PERF_LIMIT_REASONS_LOG_MASK, 0);
+
+       return 0;
+}
+DEFINE_SIMPLE_ATTRIBUTE(perf_limit_reasons_fops, perf_limit_reasons_get,
+                       perf_limit_reasons_clear, "%llu\n");
+
 void intel_gt_pm_debugfs_register(struct intel_gt *gt, struct dentry *root)
 {
        static const struct intel_gt_debugfs_file files[] = {
@@ -664,6 +694,7 @@ void intel_gt_pm_debugfs_register(struct intel_gt *gt, struct dentry *root)
                { "forcewake_user", &forcewake_user_fops, NULL},
                { "llc", &llc_fops, llc_eval },
                { "rps_boost", &rps_boost_fops, rps_eval },
+               { "perf_limit_reasons", &perf_limit_reasons_fops, NULL },
        };
 
        intel_gt_debugfs_register_files(root, files, ARRAY_SIZE(files), gt);

diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index f44eec7f7a9c5d90bc8981b3ae7b1e220d3c73fa..2d60ecc096612b09f26d16551a6cd3ee7507e4e2 100644 (file)
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -1866,6 +1866,7 @@
 #define   POWER_LIMIT_4_MASK           REG_BIT(8)
 #define   POWER_LIMIT_1_MASK           REG_BIT(10)
 #define   POWER_LIMIT_2_MASK           REG_BIT(11)
+#define   GT0_PERF_LIMIT_REASONS_LOG_MASK REG_GENMASK(31, 16)
 
 #define CHV_CLK_CTL1                   _MMIO(0x101100)
 #define VLV_CLK_CTL2                   _MMIO(0x101104)