| Message ID | 1481641656-25227-1-git-send-email-bgolaszewski@baylibre.com |
|---|---|
| State | Accepted |
| Commit | f97fd383d9a10fd125bcdafba03240685aed5608 |
| Headers | show |
One comment bellow. On 12/13/16 17:07, 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> > --- > 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) { I would add here: + if ((tilcdc_read(dev, LCDC_RASTER_CTRL_REG) & + LCDC_RASTER_ENABLE)) { > + tilcdc_clear(dev, > + LCDC_RASTER_CTRL_REG, LCDC_RASTER_ENABLE); > + tilcdc_set(dev, > + LCDC_RASTER_CTRL_REG, LCDC_RASTER_ENABLE); + } Just in case the interrupt is for some reason handled right after the crtc is disabled. With this addition I could send a pull request for this fix still today, if you agree with the change. > + } 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; > + } > } > } > >
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; + } } }
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> --- drivers/gpu/drm/tilcdc/tilcdc_crtc.c | 24 +++++++++++++++--------- 1 file changed, 15 insertions(+), 9 deletions(-) -- 2.9.3