From c2ecef2360870f912f5feaf016304c442a8a5ded Mon Sep 17 00:00:00 2001
From: Marek Vasut <marex@denx.de>
Date: Sun, 17 Apr 2022 04:07:57 +0200
Subject: drm: mxsfb: Wrap FIFO reset and comments into mxsfb_reset_block()
Git-commit: e518a9dc81d3de494640ba0ae2677d3d43a3709b
Patch-mainline: v5.19-rc1
References: jsc#PED-1166 jsc#PED-1168 jsc#PED-1170 jsc#PED-1218 jsc#PED-1220 jsc#PED-1222 jsc#PED-1223 jsc#PED-1225

Wrap FIFO reset and comments into mxsfb_reset_block(), this is a clean up.
No functional change.

Reviewed-by: Lucas Stach <l.stach@pengutronix.de>
Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Alexander Stein <alexander.stein@ew.tq-group.com>
Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: Lucas Stach <l.stach@pengutronix.de>
Cc: Peng Fan <peng.fan@nxp.com>
Cc: Robby Cai <robby.cai@nxp.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Stefan Agner <stefan@agner.ch>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20220417020800.336675-1-marex@denx.de
Acked-by: Patrik Jakobsson <pjakobsson@suse.de>
---
 drivers/gpu/drm/mxsfb/mxsfb_kms.c | 36 +++++++++++++++++--------------
 1 file changed, 20 insertions(+), 16 deletions(-)

diff --git a/drivers/gpu/drm/mxsfb/mxsfb_kms.c b/drivers/gpu/drm/mxsfb/mxsfb_kms.c
index 4cfb6c001679..45cabe096076 100644
--- a/drivers/gpu/drm/mxsfb/mxsfb_kms.c
+++ b/drivers/gpu/drm/mxsfb/mxsfb_kms.c
@@ -191,6 +191,12 @@ static int mxsfb_reset_block(struct mxsfb_drm_private *mxsfb)
 {
 	int ret;
 
+	/*
+	 * It seems, you can't re-program the controller if it is still
+	 * running. This may lead to shifted pictures (FIFO issue?), so
+	 * first stop the controller and drain its FIFOs.
+	 */
+
 	ret = clear_poll_bit(mxsfb->base + LCDC_CTRL, CTRL_SFTRST);
 	if (ret)
 		return ret;
@@ -201,7 +207,20 @@ static int mxsfb_reset_block(struct mxsfb_drm_private *mxsfb)
 	if (ret)
 		return ret;
 
-	return clear_poll_bit(mxsfb->base + LCDC_CTRL, CTRL_CLKGATE);
+	ret = clear_poll_bit(mxsfb->base + LCDC_CTRL, CTRL_CLKGATE);
+	if (ret)
+		return ret;
+
+	/* Clear the FIFOs */
+	writel(CTRL1_FIFO_CLEAR, mxsfb->base + LCDC_CTRL1 + REG_SET);
+	readl(mxsfb->base + LCDC_CTRL1);
+	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);
+
+	return 0;
 }
 
 static dma_addr_t mxsfb_get_fb_paddr(struct drm_plane *plane)
@@ -228,26 +247,11 @@ static void mxsfb_crtc_mode_set_nofb(struct mxsfb_drm_private *mxsfb,
 	u32 vdctrl0, vsync_pulse_len, hsync_pulse_len;
 	int err;
 
-	/*
-	 * It seems, you can't re-program the controller if it is still
-	 * running. This may lead to shifted pictures (FIFO issue?), so
-	 * first stop the controller and drain its FIFOs.
-	 */
-
 	/* Mandatory eLCDIF reset as per the Reference Manual */
 	err = mxsfb_reset_block(mxsfb);
 	if (err)
 		return;
 
-	/* Clear the FIFOs */
-	writel(CTRL1_FIFO_CLEAR, mxsfb->base + LCDC_CTRL1 + REG_SET);
-	readl(mxsfb->base + LCDC_CTRL1);
-	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);
-
 	mxsfb_set_formats(mxsfb, bus_format);
 
 	clk_set_rate(mxsfb->clk, m->crtc_clock * 1000);
-- 
2.38.1