[PATCH v3 3/8] drm: lcdif: enable DMA before display

[Lucas Stach]

Otherwise the DMA enable races with the fetch start, which causes
wrong or no data to be scanned out on the first frame. Also there
is no point in waiting for the DMA disable when the controller is
going to shut down. Simply disable the display first so no further
fetches are triggered and then shut down DMA.

Signed-off-by: Lucas Stach <l.stach at pengutronix.de>
---
v3: new patch
---
 drivers/gpu/drm/mxsfb/lcdif_kms.c | 23 ++++++++---------------
 1 file changed, 8 insertions(+), 15 deletions(-)

diff --git a/drivers/gpu/drm/mxsfb/lcdif_kms.c b/drivers/gpu/drm/mxsfb/lcdif_kms.c
index e277592e5fa5..6a292f4b332b 100644
--- a/drivers/gpu/drm/mxsfb/lcdif_kms.c
+++ b/drivers/gpu/drm/mxsfb/lcdif_kms.c
@@ -358,34 +358,27 @@ static void lcdif_enable_controller(struct lcdif_drm_private *lcdif)
 	writel(INT_ENABLE_D1_PLANE_PANIC_EN,
 	       lcdif->base + LCDC_V8_INT_ENABLE_D1);
 
-	reg = readl(lcdif->base + LCDC_V8_DISP_PARA);
-	reg |= DISP_PARA_DISP_ON;
-	writel(reg, lcdif->base + LCDC_V8_DISP_PARA);
-
 	reg = readl(lcdif->base + LCDC_V8_CTRLDESCL0_5);
 	reg |= CTRLDESCL0_5_EN;
 	writel(reg, lcdif->base + LCDC_V8_CTRLDESCL0_5);
+
+	reg = readl(lcdif->base + LCDC_V8_DISP_PARA);
+	reg |= DISP_PARA_DISP_ON;
+	writel(reg, lcdif->base + LCDC_V8_DISP_PARA);
 }
 
 static void lcdif_disable_controller(struct lcdif_drm_private *lcdif)
 {
 	u32 reg;
-	int ret;
-
-	reg = readl(lcdif->base + LCDC_V8_CTRLDESCL0_5);
-	reg &= ~CTRLDESCL0_5_EN;
-	writel(reg, lcdif->base + LCDC_V8_CTRLDESCL0_5);
-
-	ret = readl_poll_timeout(lcdif->base + LCDC_V8_CTRLDESCL0_5,
-				 reg, !(reg & CTRLDESCL0_5_EN),
-				 0, 36000);	/* Wait ~2 frame times max */
-	if (ret)
-		drm_err(lcdif->drm, "Failed to disable controller!\n");
 
 	reg = readl(lcdif->base + LCDC_V8_DISP_PARA);
 	reg &= ~DISP_PARA_DISP_ON;
 	writel(reg, lcdif->base + LCDC_V8_DISP_PARA);
 
+	reg = readl(lcdif->base + LCDC_V8_CTRLDESCL0_5);
+	reg &= ~CTRLDESCL0_5_EN;
+	writel(reg, lcdif->base + LCDC_V8_CTRLDESCL0_5);
+
 	/* Disable FIFO Panic NoC priority booster. */
 	writel(0, lcdif->base + LCDC_V8_INT_ENABLE_D1);
 }
-- 
2.39.2