From mboxrd@z Thu Jan 1 00:00:00 1970 From: Fabio Estevam Date: Tue, 29 Jan 2013 02:39:31 +0000 Subject: [PATCH RESEND v4] video: imxfb: Do not crash on reboot Message-Id: <1359427171-18109-1-git-send-email-festevam@gmail.com> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-fbdev@vger.kernel.org From: Fabio Estevam 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: [] (unwind_backtrace+0x0/0xf4) from [] (warn_slowpath_common+0x48/0x60) [] (warn_slowpath_common+0x48/0x60) from [] (warn_slowpath_null+0x1c/0x24) [] (warn_slowpath_null+0x1c/0x24) from [] (clk_disable+0x24/0x50) [] (clk_disable+0x24/0x50) from [] (imxfb_disable_controller+0x48/0x7c) [] (imxfb_disable_controller+0x48/0x7c) from [] (platform_drv_shutdown+0x18/0x1c) [] (platform_drv_shutdown+0x18/0x1c) from [] (device_shutdown+0x48/0x14c) [] (device_shutdown+0x48/0x14c) from [] (kernel_restart_prepare+0x2c/0x3c) [] (kernel_restart_prepare+0x2c/0x3c) from [] (kernel_restart+0xc/0x48) [] (kernel_restart+0xc/0x48) from [] (sys_reboot+0xc0/0x1bc) [] (sys_reboot+0xc0/0x1bc) from [] (ret_fast_syscall+0x0/0x2c) ---[ end trace da6b502ca79c854f ]--- ------------[ cut here ]------------ WARNING: at drivers/clk/clk.c:380 clk_unprepare+0x1c/0x2c() Modules linked in: [] (unwind_backtrace+0x0/0xf4) from [] (warn_slowpath_common+0x48/0x60) [] (warn_slowpath_common+0x48/0x60) from [] (warn_slowpath_null+0x1c/0x24) [] (warn_slowpath_null+0x1c/0x24) from [] (clk_unprepare+0x1c/0x2c) [] (clk_unprepare+0x1c/0x2c) from [] (imxfb_disable_controller+0x50/0x7c) [] (imxfb_disable_controller+0x50/0x7c) from [] (platform_drv_shutdown+0x18/0x1c) [] (platform_drv_shutdown+0x18/0x1c) from [] (device_shutdown+0x48/0x14c) [] (device_shutdown+0x48/0x14c) from [] (kernel_restart_prepare+0x2c/0x3c) [] (kernel_restart_prepare+0x2c/0x3c) from [] (kernel_restart+0xc/0x48) [] (kernel_restart+0xc/0x48) from [] (sys_reboot+0xc0/0x1bc) [] (sys_reboot+0xc0/0x1bc) from [] (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 Signed-off-by: Fabio Estevam --- Changes since v3: - Changed from 'clks_enabled' to 'enabled' Changes since v2: - Use a better naming for the clk enabled variable - Return immediately in imxfb_enable_controller/imxfb_disable_controller if the the clocks are already enabled/disabled. Changes since v1: - Protect the whole function instead of only the clocks drivers/video/imxfb.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/drivers/video/imxfb.c b/drivers/video/imxfb.c index cf2688d..ce7de9f 100644 --- a/drivers/video/imxfb.c +++ b/drivers/video/imxfb.c @@ -134,6 +134,7 @@ struct imxfb_info { struct clk *clk_ipg; struct clk *clk_ahb; struct clk *clk_per; + int enabled; /* * These are the addresses we mapped @@ -513,6 +514,10 @@ 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); @@ -533,6 +538,7 @@ 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 = 1; if (fbi->backlight_power) fbi->backlight_power(1); @@ -542,6 +548,9 @@ 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) @@ -552,6 +561,7 @@ 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 = 0; writel(0, fbi->regs + LCDC_RMCR); } -- 1.7.9.5