[PATCH] drm/tilcdc: do the complete reset sequence if the LCDC is enabled

[Emiliano Ingrassia]

If the LCD controller was already enabled (e.g. by the bootloader),
do the complete software reset sequence to avoid time out while loading
the palette and a consequent time out waiting for vblank.

Signed-off-by: Emiliano Ingrassia <ingras...@epigenesys.com>
---
 drivers/gpu/drm/tilcdc/tilcdc_crtc.c | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/drivers/gpu/drm/tilcdc/tilcdc_crtc.c 
b/drivers/gpu/drm/tilcdc/tilcdc_crtc.c
index 3621ff42979f..589156b2f76c 100644
--- a/drivers/gpu/drm/tilcdc/tilcdc_crtc.c
+++ b/drivers/gpu/drm/tilcdc/tilcdc_crtc.c
@@ -208,10 +208,33 @@ static void reset(struct drm_crtc *crtc)
 {
        struct drm_device *dev = crtc->dev;
        struct tilcdc_drm_private *priv = dev->dev_private;
+       struct tilcdc_crtc *tilcdc_crtc = to_tilcdc_crtc(crtc);
+       int ret;
 
        if (priv->rev != 2)
                return;
 
+       /*
+        * If the LCDC was already enabled (e.g. by the bootloader)
+        * do the complete software reset sequence.
+        */
+       if (tilcdc_read(dev, LCDC_RASTER_CTRL_REG) & LCDC_RASTER_ENABLE) {
+
+               /* Enable DMA Frame Done Interrupt */
+               tilcdc_write(dev, LCDC_INT_ENABLE_SET_REG, LCDC_FRAME_DONE);
+               tilcdc_clear_irqstatus(dev, 0xffffffff);
+
+               tilcdc_crtc->frame_done = false;
+               tilcdc_clear(dev, LCDC_RASTER_CTRL_REG, LCDC_RASTER_ENABLE);
+
+               ret = wait_event_timeout(tilcdc_crtc->frame_done_wq,
+                                        tilcdc_crtc->frame_done,
+                                        msecs_to_jiffies(500));
+               if (ret == 0)
+                       dev_err(dev->dev, "%s: timeout waiting for framedone 
while resetting LCDC\n",
+                               __func__);
+       }
+
        tilcdc_set(dev, LCDC_CLK_RESET_REG, LCDC_CLK_MAIN_RESET);
        usleep_range(250, 1000);
        tilcdc_clear(dev, LCDC_CLK_RESET_REG, LCDC_CLK_MAIN_RESET);
-- 
2.11.0

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