video: s3c-fb: add video clock running at data under-flow

This patch adds video clock running at data under-flow.
It means that the pixel clock is continuously provided
to lcd module, even when under-run occurs.

Signed-off-by: Jingoo Han <jg1.han@samsung.com>
Signed-off-by: Florian Tobias Schandinat <FlorianSchandinat@gmx.de>

arch/arm/plat-samsung/include/plat/regs-fb.h

@@ -91,6 +91,9 @@
 #define VIDCON1_VSTATUS_BACKPORCH		(0x1 << 13)
 #define VIDCON1_VSTATUS_ACTIVE			(0x2 << 13)
 #define VIDCON1_VSTATUS_FRONTPORCH		(0x0 << 13)
+#define VIDCON1_VCLK_MASK			(0x3 << 9)
+#define VIDCON1_VCLK_HOLD			(0x0 << 9)
+#define VIDCON1_VCLK_RUN			(0x1 << 9)
 
 #define VIDCON1_INV_VCLK			(1 << 7)
 #define VIDCON1_INV_HSYNC			(1 << 6)

drivers/video/s3c-fb.c

@@ -84,6 +84,7 @@ struct s3c_fb;
  * @has_shadowcon: Set if has SHADOWCON register.
  * @has_blendcon: Set if has BLENDCON register.
  * @has_clksel: Set if VIDCON0 register has CLKSEL bit.
+ * @has_fixvclk: Set if VIDCON1 register has FIXVCLK bits.
  */
 struct s3c_fb_variant {
 	unsigned int	is_2443:1;
@@ -103,6 +104,7 @@ struct s3c_fb_variant {
 	unsigned int	has_shadowcon:1;
 	unsigned int	has_blendcon:1;
 	unsigned int	has_clksel:1;
+	unsigned int	has_fixvclk:1;
 };
 
 /**
@@ -1358,6 +1360,7 @@ static int __devinit s3c_fb_probe(struct platform_device *pdev)
 	struct resource *res;
 	int win;
 	int ret = 0;
+	u32 reg;
 
 	platid = platform_get_device_id(pdev);
 	fbdrv = (struct s3c_fb_driverdata *)platid->driver_data;
@@ -1448,6 +1451,14 @@ static int __devinit s3c_fb_probe(struct platform_device *pdev)
 
 	writel(pd->vidcon1, sfb->regs + VIDCON1);
 
+	/* set video clock running at under-run */
+	if (sfb->variant.has_fixvclk) {
+		reg = readl(sfb->regs + VIDCON1);
+		reg &= ~VIDCON1_VCLK_MASK;
+		reg |= VIDCON1_VCLK_RUN;
+		writel(reg, sfb->regs + VIDCON1);
+	}
+
 	/* zero all windows before we do anything */
 
 	for (win = 0; win < fbdrv->variant.nr_windows; win++)
@@ -1571,6 +1582,7 @@ static int s3c_fb_resume(struct device *dev)
 	struct s3c_fb_platdata *pd = sfb->pdata;
 	struct s3c_fb_win *win;
 	int win_no;
+	u32 reg;
 
 	clk_enable(sfb->bus_clk);
 
@@ -1581,6 +1593,14 @@ static int s3c_fb_resume(struct device *dev)
 	pd->setup_gpio();
 	writel(pd->vidcon1, sfb->regs + VIDCON1);
 
+	/* set video clock running at under-run */
+	if (sfb->variant.has_fixvclk) {
+		reg = readl(sfb->regs + VIDCON1);
+		reg &= ~VIDCON1_VCLK_MASK;
+		reg |= VIDCON1_VCLK_RUN;
+		writel(reg, sfb->regs + VIDCON1);
+	}
+
 	/* zero all windows before we do anything */
 	for (win_no = 0; win_no < sfb->variant.nr_windows; win_no++)
 		s3c_fb_clear_win(sfb, win_no);
@@ -1845,6 +1865,7 @@ static struct s3c_fb_driverdata s3c_fb_data_s5pv210 = {
 		.has_shadowcon	= 1,
 		.has_blendcon	= 1,
 		.has_clksel	= 1,
+		.has_fixvclk	= 1,
 	},
 	.win[0]	= &s3c_fb_data_s5p_wins[0],
 	.win[1]	= &s3c_fb_data_s5p_wins[1],
@@ -1876,6 +1897,7 @@ static struct s3c_fb_driverdata s3c_fb_data_exynos4 = {
 
 		.has_shadowcon	= 1,
 		.has_blendcon	= 1,
+		.has_fixvclk	= 1,
 	},
 	.win[0]	= &s3c_fb_data_s5p_wins[0],
 	.win[1]	= &s3c_fb_data_s5p_wins[1],
@@ -1941,6 +1963,7 @@ static struct s3c_fb_driverdata s3c_fb_data_s5p64x0 = {
 		},
 
 		.has_blendcon	= 1,
+		.has_fixvclk	= 1,
 	},
 	.win[0] = &s3c_fb_data_s5p_wins[0],
 	.win[1] = &s3c_fb_data_s5p_wins[1],