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drm: tilcdc: simplify the recovery from sync lost error on rev1 

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>
Reviewed-by: Jyri Sarha <jsarha@ti.com>
Signed-off-by: Jyri Sarha <jsarha@ti.com>
This commit is contained in:
Bartosz Golaszewski 2016-12-19 15:47:14 +01:00 committed by Jyri Sarha
parent 0186fcce89
commit f97fd383d9
1 changed files with 18 additions and 9 deletions
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27
drivers/gpu/drm/tilcdc/tilcdc_crtc.c
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@ -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;
}
}
}