Bit 21 can alter the CTRL2_OUTSTANDING_REQS value right after the eLCDIF
is enabled, since it comes up with default value of 1 (this behaviour
has been seen on some imx8 platforms).
In order to fix this, clear CTRL2_OUTSTANDING_REQS bits before setting
its value.
Signed-off-by: Robert Chiras <robert.chiras@xxxxxxx>
Tested-by: Guido Günther <agx@xxxxxxxxxxx>
---
drivers/gpu/drm/mxsfb/mxsfb_crtc.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/drivers/gpu/drm/mxsfb/mxsfb_crtc.c b/drivers/gpu/drm/mxsfb/mxsfb_crtc.c
index e727f5e..a12f53d 100644
--- a/drivers/gpu/drm/mxsfb/mxsfb_crtc.c
+++ b/drivers/gpu/drm/mxsfb/mxsfb_crtc.c
@@ -225,6 +225,13 @@ static void mxsfb_enable_controller(struct mxsfb_drm_private *mxsfb)
clk_prepare_enable(mxsfb->clk);
if (mxsfb->devdata->ipversion >= 4) {
+ /*
+ * On some platforms, bit 21 is defaulted to 1, which may alter
+ * the below setting. So, to make sure we have the right setting
+ * clear all the bits for CTRL2_OUTSTANDING_REQS.
+ */
+ writel(CTRL2_OUTSTANDING_REQS(0x7),
+ mxsfb->base + LCDC_V4_CTRL2 + REG_CLR);
writel(CTRL2_OUTSTANDING_REQS(REQ_16),
mxsfb->base + LCDC_V4_CTRL2 + REG_SET);
/* Assert LCD Reset bit */
--
2.7.4
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