linux-kernel - [PATCH v4 04/14] drm/mxsfb: Reset vital registers for a proper initialization

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Message-Id: <1567078215-31601-5-git-send-email-robert.chiras@nxp.com>
Date:   Thu, 29 Aug 2019 14:30:05 +0300
From:   Robert Chiras <robert.chiras@....com>
To:     Guido Günther <agx@...xcpu.org>,
        Marek Vasut <marex@...x.de>, Stefan Agner <stefan@...er.ch>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Shawn Guo <shawnguo@...nel.org>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        Fabio Estevam <festevam@...il.com>
Cc:     Pengutronix Kernel Team <kernel@...gutronix.de>,
        NXP Linux Team <linux-imx@....com>,
        dri-devel@...ts.freedesktop.org, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: [PATCH v4 04/14] drm/mxsfb: Reset vital registers for a proper initialization

Some of the registers, like LCDC_CTRL, CTRL2_OUTSTANDING_REQS and
CTRL1_RECOVERY_ON_UNDERFLOW needs to be properly cleared/initialized
for a better start and stop routine.

Signed-off-by: Robert Chiras <robert.chiras@....com>
Tested-by: Guido Günther <agx@...xcpu.org>
---
 drivers/gpu/drm/mxsfb/mxsfb_crtc.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/drivers/gpu/drm/mxsfb/mxsfb_crtc.c b/drivers/gpu/drm/mxsfb/mxsfb_crtc.c
index b69ace8..5e44f57 100644
--- a/drivers/gpu/drm/mxsfb/mxsfb_crtc.c
+++ b/drivers/gpu/drm/mxsfb/mxsfb_crtc.c
@@ -127,6 +127,10 @@ static void mxsfb_enable_controller(struct mxsfb_drm_private *mxsfb)
 		clk_prepare_enable(mxsfb->clk_disp_axi);
 	clk_prepare_enable(mxsfb->clk);
 
+	if (mxsfb->devdata->ipversion >= 4)
+		writel(CTRL2_OUTSTANDING_REQS(REQ_16),
+		       mxsfb->base + LCDC_V4_CTRL2 + REG_SET);
+
 	/* If it was disabled, re-enable the mode again */
 	writel(CTRL_DOTCLK_MODE, mxsfb->base + LCDC_CTRL + REG_SET);
 
@@ -136,12 +140,19 @@ static void mxsfb_enable_controller(struct mxsfb_drm_private *mxsfb)
 	writel(reg, mxsfb->base + LCDC_VDCTRL4);
 
 	writel(CTRL_RUN, mxsfb->base + LCDC_CTRL + REG_SET);
+	writel(CTRL1_RECOVERY_ON_UNDERFLOW, mxsfb->base + LCDC_CTRL1 + REG_SET);
 }
 
 static void mxsfb_disable_controller(struct mxsfb_drm_private *mxsfb)
 {
 	u32 reg;
 
+	if (mxsfb->devdata->ipversion >= 4)
+		writel(CTRL2_OUTSTANDING_REQS(0x7),
+		       mxsfb->base + LCDC_V4_CTRL2 + REG_CLR);
+
+	writel(CTRL_RUN, mxsfb->base + LCDC_CTRL + REG_CLR);
+
 	/*
 	 * Even if we disable the controller here, it will still continue
 	 * until its FIFOs are running out of data
@@ -295,6 +306,7 @@ void mxsfb_crtc_enable(struct mxsfb_drm_private *mxsfb)
 	dma_addr_t paddr;
 
 	mxsfb_enable_axi_clk(mxsfb);
+	writel(0, mxsfb->base + LCDC_CTRL);
 	mxsfb_crtc_mode_set_nofb(mxsfb);
 
 	/* Write cur_buf as well to avoid an initial corrupt frame */
-- 
2.7.4