Commit e6b267ce authored Jan 16, 2013 by Fabio Estevam Committed by Shawn Guo Jan 17, 2013

video: imxfb: Do not crash on reboot



Issuing a "reboot" command after the LCD times out causes the following
warnings:

Requesting system reboot
------------[ cut here ]------------
WARNING: at drivers/clk/clk.c:471 clk_disable+0x24/0x50()
Modules linked in:
[<c001ad90>] (unwind_backtrace+0x0/0xf4) from [<c0025aac>] (warn_slowpath_common+0x48/0x60)
[<c0025aac>] (warn_slowpath_common+0x48/0x60) from [<c0025ae0>] (warn_slowpath_null+0x1c/0x24)
[<c0025ae0>] (warn_slowpath_null+0x1c/0x24) from [<c03960a0>] (clk_disable+0x24/0x50)
[<c03960a0>] (clk_disable+0x24/0x50) from [<c02695a0>] (imxfb_disable_controller+0x48/0x7c)
[<c02695a0>] (imxfb_disable_controller+0x48/0x7c) from [<c029d838>] (platform_drv_shutdown+0x18/0x1c)
[<c029d838>] (platform_drv_shutdown+0x18/0x1c) from [<c02990fc>] (device_shutdown+0x48/0x14c)
[<c02990fc>] (device_shutdown+0x48/0x14c) from [<c003d09c>] (kernel_restart_prepare+0x2c/0x3c)
[<c003d09c>] (kernel_restart_prepare+0x2c/0x3c) from [<c003d0e4>] (kernel_restart+0xc/0x48)
[<c003d0e4>] (kernel_restart+0xc/0x48) from [<c003d1e8>] (sys_reboot+0xc0/0x1bc)
[<c003d1e8>] (sys_reboot+0xc0/0x1bc) from [<c0014ca0>] (ret_fast_syscall+0x0/0x2c)
---[ end trace da6b502ca79c854f ]---
------------[ cut here ]------------
WARNING: at drivers/clk/clk.c:380 clk_unprepare+0x1c/0x2c()
Modules linked in:
[<c001ad90>] (unwind_backtrace+0x0/0xf4) from [<c0025aac>] (warn_slowpath_common+0x48/0x60)
[<c0025aac>] (warn_slowpath_common+0x48/0x60) from [<c0025ae0>] (warn_slowpath_null+0x1c/0x24)
[<c0025ae0>] (warn_slowpath_null+0x1c/0x24) from [<c0396338>] (clk_unprepare+0x1c/0x2c)
[<c0396338>] (clk_unprepare+0x1c/0x2c) from [<c02695a8>] (imxfb_disable_controller+0x50/0x7c)
[<c02695a8>] (imxfb_disable_controller+0x50/0x7c) from [<c029d838>] (platform_drv_shutdown+0x18/0x1c)
[<c029d838>] (platform_drv_shutdown+0x18/0x1c) from [<c02990fc>] (device_shutdown+0x48/0x14c)
[<c02990fc>] (device_shutdown+0x48/0x14c) from [<c003d09c>] (kernel_restart_prepare+0x2c/0x3c)
[<c003d09c>] (kernel_restart_prepare+0x2c/0x3c) from [<c003d0e4>] (kernel_restart+0xc/0x48)
[<c003d0e4>] (kernel_restart+0xc/0x48) from [<c003d1e8>] (sys_reboot+0xc0/0x1bc)
[<c003d1e8>] (sys_reboot+0xc0/0x1bc) from [<c0014ca0>] (ret_fast_syscall+0x0/0x2c)
---[ end trace da6b502ca79c8550 ]---
------------[ cut here ]------------

This happens because "reboot" triggers imxfb_shutdown(), which calls
imxfb_disable_controller with the clocks already disabled.

To prevent this, add a clock enabled status so that we can check if the clocks
are enabled before disabling them.

Acked-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>

parent 83ae2098

drivers/video/imxfb.c

+10 −0

Original line number	Diff line number	Diff line
		@@ -139,6 +139,7 @@ struct imxfb_info {
		struct clk *clk_ahb;
		struct clk *clk_per;
		enum imxfb_type devtype;
		bool enabled;

		/*
		* These are the addresses we mapped
		@@ -536,6 +537,10 @@ static void imxfb_exit_backlight(struct imxfb_info *fbi)

		static void imxfb_enable_controller(struct imxfb_info *fbi)
		{

		if (fbi->enabled)
		return;

		pr_debug("Enabling LCD controller\n");

		writel(fbi->screen_dma, fbi->regs + LCDC_SSA);
		@@ -556,6 +561,7 @@ static void imxfb_enable_controller(struct imxfb_info *fbi)
		clk_prepare_enable(fbi->clk_ipg);
		clk_prepare_enable(fbi->clk_ahb);
		clk_prepare_enable(fbi->clk_per);
		fbi->enabled = true;

		if (fbi->backlight_power)
		fbi->backlight_power(1);
		@@ -565,6 +571,9 @@ static void imxfb_enable_controller(struct imxfb_info *fbi)

		static void imxfb_disable_controller(struct imxfb_info *fbi)
		{
		if (!fbi->enabled)
		return;

		pr_debug("Disabling LCD controller\n");

		if (fbi->backlight_power)
		@@ -575,6 +584,7 @@ static void imxfb_disable_controller(struct imxfb_info *fbi)
		clk_disable_unprepare(fbi->clk_per);
		clk_disable_unprepare(fbi->clk_ipg);
		clk_disable_unprepare(fbi->clk_ahb);
		fbi->enabled = false;

		writel(0, fbi->regs + LCDC_RMCR);
		}

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