Am Montag, dem 21.06.2021 um 00:49 +0200 schrieb Marek Vasut:
Make sure the FIFO_CLEAR bit is latched in when configuring the controller, so that the FIFO is really cleared. And then clear the FIFO_CLEAR bit, since it is not self-clearing.
Fixes: 45d59d704080 ("drm: Add new driver for MXSFB controller") Signed-off-by: Marek Vasut marex@denx.de Cc: Daniel Abrecht public@danielabrecht.ch Cc: Emil Velikov emil.l.velikov@gmail.com Cc: Laurent Pinchart laurent.pinchart@ideasonboard.com Cc: Lucas Stach l.stach@pengutronix.de Cc: Stefan Agner stefan@agner.ch
drivers/gpu/drm/mxsfb/mxsfb_kms.c | 3 +++ 1 file changed, 3 insertions(+)
diff --git a/drivers/gpu/drm/mxsfb/mxsfb_kms.c b/drivers/gpu/drm/mxsfb/mxsfb_kms.c index 98d8ba0bae84..22cb749fc9bc 100644 --- a/drivers/gpu/drm/mxsfb/mxsfb_kms.c +++ b/drivers/gpu/drm/mxsfb/mxsfb_kms.c @@ -241,6 +241,9 @@ static void mxsfb_crtc_mode_set_nofb(struct mxsfb_drm_private *mxsfb,
/* Clear the FIFOs */ writel(CTRL1_FIFO_CLEAR, mxsfb->base + LCDC_CTRL1 + REG_SET);
- readl(mxsfb->base + LCDC_CTRL1);
Do you really need those readbacks? As both writes are targeting the same slave interface, the memory barrier in the clear write should push the set write.
writel(CTRL1_FIFO_CLEAR, mxsfb->base + LCDC_CTRL1 + REG_CLR);
readl(mxsfb->base + LCDC_CTRL1);
if (mxsfb->devdata->has_overlay) writel(0, mxsfb->base + LCDC_AS_CTRL);