On 12/19/16 16:47, Bartosz Golaszewski wrote:

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@baylibre.com

After testing I'll send this as fixes pull req for tilcdc 4.10.

Reviewed-by: Jyri Sarha jsarha@ti.com

---

v1 -> v2:

• add a check to see if the RASTER_ENABLE bit is set before clearing it

drivers/gpu/drm/tilcdc/tilcdc_crtc.c | 27 ++++++++++++++++++--------- 1 file changed, 18 insertions(+), 9 deletions(-)

diff --git a/drivers/gpu/drm/tilcdc/tilcdc_crtc.c b/drivers/gpu/drm/tilcdc/tilcdc_crtc.c index 9942b05..2004107 100644 --- a/drivers/gpu/drm/tilcdc/tilcdc_crtc.c +++ b/drivers/gpu/drm/tilcdc/tilcdc_crtc.c @@ -856,7 +856,7 @@ irqreturn_t tilcdc_crtc_irq(struct drm_crtc *crtc) struct tilcdc_crtc *tilcdc_crtc = to_tilcdc_crtc(crtc); struct drm_device *dev = crtc->dev; struct tilcdc_drm_private *priv = dev->dev_private;

• uint32_t stat;

• uint32_t stat, reg;

  stat = tilcdc_read_irqstatus(dev); tilcdc_clear_irqstatus(dev, stat);

@@ -921,17 +921,26 @@ 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)
  

• if (priv->rev == 1) {
  

• 	reg = tilcdc_read(dev, LCDC_RASTER_CTRL_REG);
  

• 	if (reg & LCDC_RASTER_ENABLE) {
  	tilcdc_clear(dev, LCDC_RASTER_CTRL_REG,
  

• 			     LCDC_V1_SYNC_LOST_INT_ENA);
  

• 	else
  

• 			     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;
  

• 	}
  

  } }