Revision 2 of LCDC suffers from an issue where a SYNC_LOST error
caused by limited memory bandwidth may leave the picture shifted a
couple pixels to the right.
This issue has not been observed on revision 1, while the recovery
mechanism introduces a different issue, where the END_OF_FRAME
interrupt doesn't fire while drm is waiting for vblanks.
On rev1: recover from sync lost errors by simply clearing the
RASTER_ENABLE bit in the RASTER_CTRL register and re-enabling it
again as is suggested by the datasheet.
Signed-off-by: Bartosz Golaszewski <bgolaszewski at baylibre.com>
---
drivers/gpu/drm/tilcdc/tilcdc_crtc.c | 24 +++++++++++++++---------
1 file changed, 15 insertions(+), 9 deletions(-)
diff --git a/drivers/gpu/drm/tilcdc/tilcdc_crtc.c
b/drivers/gpu/drm/tilcdc/tilcdc_crtc.c
index 9942b05..70e57a7 100644
--- a/drivers/gpu/drm/tilcdc/tilcdc_crtc.c
+++ b/drivers/gpu/drm/tilcdc/tilcdc_crtc.c
@@ -921,17 +921,23 @@ irqreturn_t tilcdc_crtc_irq(struct drm_crtc *crtc)
dev_err_ratelimited(dev->dev, "%s(0x%08x): Sync lost",
__func__, stat);
tilcdc_crtc->frame_intact = false;
- if (tilcdc_crtc->sync_lost_count++ >
- SYNC_LOST_COUNT_LIMIT) {
- dev_err(dev->dev, "%s(0x%08x): Sync lost flood
detected, recovering", __func__, stat);
- queue_work(system_wq, &tilcdc_crtc->recover_work);
- if (priv->rev == 1)
- tilcdc_clear(dev, LCDC_RASTER_CTRL_REG,
- LCDC_V1_SYNC_LOST_INT_ENA);
- else
+ if (priv->rev == 1) {
+ tilcdc_clear(dev,
+ LCDC_RASTER_CTRL_REG, LCDC_RASTER_ENABLE);
+ tilcdc_set(dev,
+ LCDC_RASTER_CTRL_REG, LCDC_RASTER_ENABLE);
+ } else {
+ if (tilcdc_crtc->sync_lost_count++ >
+ SYNC_LOST_COUNT_LIMIT) {
+ dev_err(dev->dev,
+ "%s(0x%08x): Sync lost flood detected,
recovering",
+ __func__, stat);
+ queue_work(system_wq,
+ &tilcdc_crtc->recover_work);
tilcdc_write(dev, LCDC_INT_ENABLE_CLR_REG,
LCDC_SYNC_LOST);
- tilcdc_crtc->sync_lost_count = 0;
+ tilcdc_crtc->sync_lost_count = 0;
+ }
}
}
--
2.9.3
