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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Marek Vasut <marex@denx.de>,
        Daniel Abrecht <public@danielabrecht.ch>,
        Emil Velikov <emil.l.velikov@gmail.com>,
        Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
        Lucas Stach <l.stach@pengutronix.de>,
        Stefan Agner <stefan@agner.ch>,
        Jagan Teki <jagan@amarulasolutions.com>,
        Sam Ravnborg <sam@ravnborg.org>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.13 130/300] drm: mxsfb: Clear FIFO_CLEAR bit
Date:   Mon, 13 Sep 2021 15:13:11 +0200
Message-Id: <20210913131113.786686781@linuxfoundation.org>
In-Reply-To: <20210913131109.253835823@linuxfoundation.org>
References: <20210913131109.253835823@linuxfoundation.org>
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From: Marek Vasut <marex@denx.de>

[ Upstream commit 5e23c98178eb1a2cdb7c4fee9a39baf8cabf282d ]

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>
Reviewed-by: Jagan Teki <jagan@amarulasolutions.com>
Tested-by: Jagan Teki <jagan@amarulasolutions.com> # i.Core MX8MM
Acked-by: Lucas Stach <l.stach@pengutronix.de>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20210620224946.189524-1-marex@denx.de
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 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 5bcc06c1ac0b..54f905ac75c0 100644
--- a/drivers/gpu/drm/mxsfb/mxsfb_kms.c
+++ b/drivers/gpu/drm/mxsfb/mxsfb_kms.c
@@ -243,6 +243,9 @@ 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);
+	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);
-- 
2.30.2