drm/i915: Save latest known sink CRC to compensate delayed counter reset.
By Vesa DP 1.2 Spec TEST_CRC_COUNT should be
"reset to 0 when TEST_SINK bit 0 = 0."
However for some strange reason when PSR is enabled in
certain platforms this is not true. At least not immediatelly.
So we face cases like this:
first get_sink_crc operation:
count: 0, crc: 000000000000
count: 1, crc: c101c101c101
returned expected crc: c101c101c101
secont get_sink_crc operation:
count: 1, crc: c101c101c101
count: 0, crc: 000000000000
count: 1, crc: 0000c1010000
should return expected crc: 0000c1010000
But also the reset to 0 should be faster resulting into:
get_sink_crc operation:
count: 1, crc: c101c101c101
count: 1, crc: 0000c1010000
should return expected crc: 0000c1010000
So in order to know that the second one is valid one
we need to compare the pair (count, crc) with latest (count, crc).
If the pair changed you have your valid CRC.
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Reviewed-by: Rafael Antognolli <rafael.antognolli@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index 1f7cc40..abcc2a3 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -4015,7 +4015,7 @@
goto out;
}
- intel_dp->sink_crc_started = false;
+ intel_dp->sink_crc.started = false;
out:
hsw_enable_ips(intel_crtc);
return ret;
@@ -4028,7 +4028,7 @@
u8 buf;
int ret;
- if (intel_dp->sink_crc_started) {
+ if (intel_dp->sink_crc.started) {
ret = intel_dp_sink_crc_stop(intel_dp);
if (ret)
return ret;
@@ -4040,6 +4040,8 @@
if (!(buf & DP_TEST_CRC_SUPPORTED))
return -ENOTTY;
+ intel_dp->sink_crc.last_count = buf & DP_TEST_COUNT_MASK;
+
if (drm_dp_dpcd_readb(&intel_dp->aux, DP_TEST_SINK, &buf) < 0)
return -EIO;
@@ -4051,7 +4053,7 @@
return -EIO;
}
- intel_dp->sink_crc_started = true;
+ intel_dp->sink_crc.started = true;
return 0;
}
@@ -4061,29 +4063,39 @@
struct drm_device *dev = dig_port->base.base.dev;
struct intel_crtc *intel_crtc = to_intel_crtc(dig_port->base.base.crtc);
u8 buf;
- int test_crc_count;
+ int count, ret;
int attempts = 6;
- int ret;
ret = intel_dp_sink_crc_start(intel_dp);
if (ret)
return ret;
- if (drm_dp_dpcd_readb(&intel_dp->aux, DP_TEST_SINK_MISC, &buf) < 0) {
- ret = -EIO;
- goto stop;
- }
-
- test_crc_count = buf & DP_TEST_COUNT_MASK;
-
do {
+ intel_wait_for_vblank(dev, intel_crtc->pipe);
+
if (drm_dp_dpcd_readb(&intel_dp->aux,
DP_TEST_SINK_MISC, &buf) < 0) {
ret = -EIO;
goto stop;
}
- intel_wait_for_vblank(dev, intel_crtc->pipe);
- } while (--attempts && (buf & DP_TEST_COUNT_MASK) == test_crc_count);
+ count = buf & DP_TEST_COUNT_MASK;
+ /*
+ * Count might be reset during the loop. In this case
+ * last known count needs to be reset as well.
+ */
+ if (count == 0)
+ intel_dp->sink_crc.last_count = 0;
+
+ if (drm_dp_dpcd_read(&intel_dp->aux, DP_TEST_CRC_R_CR, crc, 6) < 0) {
+ ret = -EIO;
+ goto stop;
+ }
+ } while (--attempts && (count == 0 || (count == intel_dp->sink_crc.last_count &&
+ !memcmp(intel_dp->sink_crc.last_crc, crc,
+ 6 * sizeof(u8)))));
+
+ intel_dp->sink_crc.last_count = buf & DP_TEST_COUNT_MASK;
+ memcpy(intel_dp->sink_crc.last_crc, crc, 6 * sizeof(u8));
if (attempts == 0) {
DRM_DEBUG_KMS("Panel is unable to calculate CRC after 6 vblanks\n");
@@ -4091,8 +4103,6 @@
goto stop;
}
- if (drm_dp_dpcd_read(&intel_dp->aux, DP_TEST_CRC_R_CR, crc, 6) < 0)
- ret = -EIO;
stop:
intel_dp_sink_crc_stop(intel_dp);
return ret;