[PATCH 4.1 57/65] video: mxsfb: Make sure axi clock is enabled when accessing registers

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

4.1-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Liu Ying <Ying.Liu@freescale.com>

commit 2fa3b4c4a78a5db3502ab9e32630ea660ff923d0 upstream.

The LCDIF engines embedded in i.MX6sl and i.MX6sx SoCs need the axi clock
as the engine's system clock.  The clock should be enabled when accessing
LCDIF registers, otherwise the kernel would hang up.  We should also keep
the clock enabled when the engine is being active to scan out frames from
memory.  This patch makes sure the axi clock is enabled when accessing
registers so that the kernel hang up issue can be fixed.

Reported-by: Peter Chen <peter.chen@freescale.com>
Tested-by: Peter Chen <peter.chen@freescale.com>
Signed-off-by: Liu Ying <Ying.Liu@freescale.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/video/fbdev/mxsfb.c |   68 ++++++++++++++++++++++++++++++++++----------
 1 file changed, 54 insertions(+), 14 deletions(-)

--- a/drivers/video/fbdev/mxsfb.c
+++ b/drivers/video/fbdev/mxsfb.c
@@ -316,6 +316,18 @@ static int mxsfb_check_var(struct fb_var
 	return 0;
 }
 
+static inline void mxsfb_enable_axi_clk(struct mxsfb_info *host)
+{
+	if (host->clk_axi)
+		clk_prepare_enable(host->clk_axi);
+}
+
+static inline void mxsfb_disable_axi_clk(struct mxsfb_info *host)
+{
+	if (host->clk_axi)
+		clk_disable_unprepare(host->clk_axi);
+}
+
 static void mxsfb_enable_controller(struct fb_info *fb_info)
 {
 	struct mxsfb_info *host = to_imxfb_host(fb_info);
@@ -333,14 +345,13 @@ static void mxsfb_enable_controller(stru
 		}
 	}
 
-	if (host->clk_axi)
-		clk_prepare_enable(host->clk_axi);
-
 	if (host->clk_disp_axi)
 		clk_prepare_enable(host->clk_disp_axi);
 	clk_prepare_enable(host->clk);
 	clk_set_rate(host->clk, PICOS2KHZ(fb_info->var.pixclock) * 1000U);
 
+	mxsfb_enable_axi_clk(host);
+
 	/* if it was disabled, re-enable the mode again */
 	writel(CTRL_DOTCLK_MODE, host->base + LCDC_CTRL + REG_SET);
 
@@ -380,11 +391,11 @@ static void mxsfb_disable_controller(str
 	reg = readl(host->base + LCDC_VDCTRL4);
 	writel(reg & ~VDCTRL4_SYNC_SIGNALS_ON, host->base + LCDC_VDCTRL4);
 
+	mxsfb_disable_axi_clk(host);
+
 	clk_disable_unprepare(host->clk);
 	if (host->clk_disp_axi)
 		clk_disable_unprepare(host->clk_disp_axi);
-	if (host->clk_axi)
-		clk_disable_unprepare(host->clk_axi);
 
 	host->enabled = 0;
 
@@ -421,6 +432,8 @@ static int mxsfb_set_par(struct fb_info
 		mxsfb_disable_controller(fb_info);
 	}
 
+	mxsfb_enable_axi_clk(host);
+
 	/* clear the FIFOs */
 	writel(CTRL1_FIFO_CLEAR, host->base + LCDC_CTRL1 + REG_SET);
 
@@ -438,6 +451,7 @@ static int mxsfb_set_par(struct fb_info
 		ctrl |= CTRL_SET_WORD_LENGTH(3);
 		switch (host->ld_intf_width) {
 		case STMLCDIF_8BIT:
+			mxsfb_disable_axi_clk(host);
 			dev_err(&host->pdev->dev,
 					"Unsupported LCD bus width mapping\n");
 			return -EINVAL;
@@ -451,6 +465,7 @@ static int mxsfb_set_par(struct fb_info
 		writel(CTRL1_SET_BYTE_PACKAGING(0x7), host->base + LCDC_CTRL1);
 		break;
 	default:
+		mxsfb_disable_axi_clk(host);
 		dev_err(&host->pdev->dev, "Unhandled color depth of %u\n",
 				fb_info->var.bits_per_pixel);
 		return -EINVAL;
@@ -504,6 +519,8 @@ static int mxsfb_set_par(struct fb_info
 			fb_info->fix.line_length * fb_info->var.yoffset,
 			host->base + host->devdata->next_buf);
 
+	mxsfb_disable_axi_clk(host);
+
 	if (reenable)
 		mxsfb_enable_controller(fb_info);
 
@@ -582,10 +599,14 @@ static int mxsfb_pan_display(struct fb_v
 
 	offset = fb_info->fix.line_length * var->yoffset;
 
+	mxsfb_enable_axi_clk(host);
+
 	/* update on next VSYNC */
 	writel(fb_info->fix.smem_start + offset,
 			host->base + host->devdata->next_buf);
 
+	mxsfb_disable_axi_clk(host);
+
 	return 0;
 }
 
@@ -608,13 +629,17 @@ static int mxsfb_restore_mode(struct mxs
 	unsigned line_count;
 	unsigned period;
 	unsigned long pa, fbsize;
-	int bits_per_pixel, ofs;
+	int bits_per_pixel, ofs, ret = 0;
 	u32 transfer_count, vdctrl0, vdctrl2, vdctrl3, vdctrl4, ctrl;
 
+	mxsfb_enable_axi_clk(host);
+
 	/* Only restore the mode when the controller is running */
 	ctrl = readl(host->base + LCDC_CTRL);
-	if (!(ctrl & CTRL_RUN))
-		return -EINVAL;
+	if (!(ctrl & CTRL_RUN)) {
+		ret = -EINVAL;
+		goto err;
+	}
 
 	vdctrl0 = readl(host->base + LCDC_VDCTRL0);
 	vdctrl2 = readl(host->base + LCDC_VDCTRL2);
@@ -635,7 +660,8 @@ static int mxsfb_restore_mode(struct mxs
 		break;
 	case 1:
 	default:
-		return -EINVAL;
+		ret = -EINVAL;
+		goto err;
 	}
 
 	fb_info->var.bits_per_pixel = bits_per_pixel;
@@ -673,10 +699,14 @@ static int mxsfb_restore_mode(struct mxs
 
 	pa = readl(host->base + host->devdata->cur_buf);
 	fbsize = fb_info->fix.line_length * vmode->yres;
-	if (pa < fb_info->fix.smem_start)
-		return -EINVAL;
-	if (pa + fbsize > fb_info->fix.smem_start + fb_info->fix.smem_len)
-		return -EINVAL;
+	if (pa < fb_info->fix.smem_start) {
+		ret = -EINVAL;
+		goto err;
+	}
+	if (pa + fbsize > fb_info->fix.smem_start + fb_info->fix.smem_len) {
+		ret = -EINVAL;
+		goto err;
+	}
 	ofs = pa - fb_info->fix.smem_start;
 	if (ofs) {
 		memmove(fb_info->screen_base, fb_info->screen_base + ofs, fbsize);
@@ -689,7 +719,11 @@ static int mxsfb_restore_mode(struct mxs
 	clk_prepare_enable(host->clk);
 	host->enabled = 1;
 
-	return 0;
+err:
+	if (ret)
+		mxsfb_disable_axi_clk(host);
+
+	return ret;
 }
 
 static int mxsfb_init_fbinfo_dt(struct mxsfb_info *host,
@@ -915,7 +949,9 @@ static int mxsfb_probe(struct platform_d
 	}
 
 	if (!host->enabled) {
+		mxsfb_enable_axi_clk(host);
 		writel(0, host->base + LCDC_CTRL);
+		mxsfb_disable_axi_clk(host);
 		mxsfb_set_par(fb_info);
 		mxsfb_enable_controller(fb_info);
 	}
@@ -954,11 +990,15 @@ static void mxsfb_shutdown(struct platfo
 	struct fb_info *fb_info = platform_get_drvdata(pdev);
 	struct mxsfb_info *host = to_imxfb_host(fb_info);
 
+	mxsfb_enable_axi_clk(host);
+
 	/*
 	 * Force stop the LCD controller as keeping it running during reboot
 	 * might interfere with the BootROM's boot mode pads sampling.
 	 */
 	writel(CTRL_RUN, host->base + LCDC_CTRL + REG_CLR);
+
+	mxsfb_disable_axi_clk(host);
 }
 
 static struct platform_driver mxsfb_driver = {