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Commit f97fd383 authored by Bartosz Golaszewski's avatar Bartosz Golaszewski Committed by Jyri Sarha
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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: default avatarBartosz Golaszewski <bgolaszewski@baylibre.com>
Reviewed-by: default avatarJyri Sarha <jsarha@ti.com>
Signed-off-by: default avatarJyri Sarha <jsarha@ti.com>
parent 0186fcce

drivers/gpu/drm/tilcdc/tilcdc_crtc.c

+18 −9
Original line number Diff line number Diff line
@@ -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);
@@ -921,19 +921,28 @@ 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 (priv->rev == 1) {

			reg = tilcdc_read(dev, LCDC_RASTER_CTRL_REG);

			if (reg & LCDC_RASTER_ENABLE) {

				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);

			if (priv->rev == 1)

				tilcdc_clear(dev, LCDC_RASTER_CTRL_REG,

					     LCDC_V1_SYNC_LOST_INT_ENA);

			else

				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;

			}

		}

	}



	if (stat & LCDC_FRAME_DONE) {

		tilcdc_crtc->frame_done = true;