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Subject[PATCH] drm/v3d: Add a little debugfs entry for measuring the core clock.
Date
This adds just enough performance counter support to measure the
clock. We don't have linux kernel drivers for the clock driving the
HW, and this was useful for determining that the V3D HW is running on
a slow clock, not that the driver was slow.

Signed-off-by: Eric Anholt <eric@anholt.net>
---
drivers/gpu/drm/v3d/v3d_debugfs.c | 35 +++++++++++++++++++++++++++++++
drivers/gpu/drm/v3d/v3d_regs.h | 30 ++++++++++++++++++++++++++
2 files changed, 65 insertions(+)

diff --git a/drivers/gpu/drm/v3d/v3d_debugfs.c b/drivers/gpu/drm/v3d/v3d_debugfs.c
index 4db62c545748..d48008adb085 100644
--- a/drivers/gpu/drm/v3d/v3d_debugfs.c
+++ b/drivers/gpu/drm/v3d/v3d_debugfs.c
@@ -176,9 +176,44 @@ static int v3d_debugfs_bo_stats(struct seq_file *m, void *unused)
return 0;
}

+static int v3d_measure_clock(struct seq_file *m, void *unused)
+{
+ struct drm_info_node *node = (struct drm_info_node *)m->private;
+ struct drm_device *dev = node->minor->dev;
+ struct v3d_dev *v3d = to_v3d_dev(dev);
+ uint32_t cycles;
+ int core = 0;
+ int measure_ms = 1000;
+
+ if (v3d->ver >= 40) {
+ V3D_CORE_WRITE(core, V3D_V4_PCTR_0_SRC_0_3,
+ V3D_SET_FIELD(V3D_PCTR_CYCLE_COUNT,
+ V3D_PCTR_S0));
+ V3D_CORE_WRITE(core, V3D_V4_PCTR_0_CLR, 1);
+ V3D_CORE_WRITE(core, V3D_V4_PCTR_0_EN, 1);
+ } else {
+ V3D_CORE_WRITE(core, V3D_V3_PCTR_0_PCTRS0,
+ V3D_PCTR_CYCLE_COUNT);
+ V3D_CORE_WRITE(core, V3D_V3_PCTR_0_CLR, 1);
+ V3D_CORE_WRITE(core, V3D_V3_PCTR_0_EN,
+ V3D_V3_PCTR_0_EN_ENABLE |
+ 1);
+ }
+ msleep(measure_ms);
+ cycles = V3D_CORE_READ(core, V3D_PCTR_0_PCTR0);
+
+ seq_printf(m, "cycles: %d (%d.%d Mhz)\n",
+ cycles,
+ cycles / (measure_ms * 1000),
+ (cycles / (measure_ms * 100)) % 10);
+
+ return 0;
+}
+
static const struct drm_info_list v3d_debugfs_list[] = {
{"v3d_ident", v3d_v3d_debugfs_ident, 0},
{"v3d_regs", v3d_v3d_debugfs_regs, 0},
+ {"measure_clock", v3d_measure_clock, 0},
{"bo_stats", v3d_debugfs_bo_stats, 0},
};

diff --git a/drivers/gpu/drm/v3d/v3d_regs.h b/drivers/gpu/drm/v3d/v3d_regs.h
index 854046565989..c3a5e4e44f73 100644
--- a/drivers/gpu/drm/v3d/v3d_regs.h
+++ b/drivers/gpu/drm/v3d/v3d_regs.h
@@ -267,6 +267,36 @@
# define V3D_PTB_BXCF_RWORDERDISA BIT(1)
# define V3D_PTB_BXCF_CLIPDISA BIT(0)

+#define V3D_V3_PCTR_0_EN 0x00674
+#define V3D_V3_PCTR_0_EN_ENABLE BIT(31)
+#define V3D_V4_PCTR_0_EN 0x00650
+/* When a bit is set, resets the counter to 0. */
+#define V3D_V3_PCTR_0_CLR 0x00670
+#define V3D_V4_PCTR_0_CLR 0x00654
+#define V3D_PCTR_0_OVERFLOW 0x00658
+
+#define V3D_V3_PCTR_0_PCTRS0 0x00684
+#define V3D_V3_PCTR_0_PCTRS15 0x00660
+#define V3D_V3_PCTR_0_PCTRSX(x) (V3D_V3_PCTR_0_PCTRS0 + \
+ 4 * (x))
+/* Each src reg muxes four counters each. */
+#define V3D_V4_PCTR_0_SRC_0_3 0x00660
+#define V3D_V4_PCTR_0_SRC_28_31 0x0067c
+# define V3D_PCTR_S0_MASK V3D_MASK(6, 0)
+# define V3D_PCTR_S0_SHIFT 0
+# define V3D_PCTR_S1_MASK V3D_MASK(14, 8)
+# define V3D_PCTR_S1_SHIFT 8
+# define V3D_PCTR_S2_MASK V3D_MASK(22, 16)
+# define V3D_PCTR_S2_SHIFT 16
+# define V3D_PCTR_S3_MASK V3D_MASK(30, 24)
+# define V3D_PCTR_S3_SHIFT 24
+# define V3D_PCTR_CYCLE_COUNT 32
+
+/* Output values of the counters. */
+#define V3D_PCTR_0_PCTR0 0x00680
+#define V3D_PCTR_0_PCTR31 0x006fc
+#define V3D_PCTR_0_PCTRX(x) (V3D_PCTR_0_PCTR0 + \
+ 4 * (x))
#define V3D_GMP_STATUS 0x00800
# define V3D_GMP_STATUS_GMPRST BIT(31)
# define V3D_GMP_STATUS_WR_COUNT_MASK V3D_MASK(30, 24)
--
2.18.0
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