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Message-id: <000201cdd283$baf50160$30df0420$%han@samsung.com>
Date: Wed, 05 Dec 2012 09:59:07 +0900
From: Jingoo Han <jg1.han@...sung.com>
To: 'Andrew Morton' <akpm@...ux-foundation.org>,
'LKML' <linux-kernel@...r.kernel.org>
Cc: 'Marko Katic' <dromede@...il.com>,
'Grant Likely' <grant.likely@...retlab.ca>,
'Florian Tobias Schandinat' <FlorianSchandinat@....de>,
'Richard Purdie' <rpurdie@...ys.net>,
linux-arm-kernel@...ts.infradead.org,
'Jingoo Han' <jg1.han@...sung.com>
Subject: [PATCH v4] backlight: corgi_lcd: Use gpio_set_value_cansleep() to
avoid WARN_ON
From: Marko Katic <dromede@...il.com>
Changing backlight intensity on an Akita (Sharp Zaurus C-1000)
triggers WARN_ON message:
WARNING: at drivers/gpio/gpiolib.c:1672 __gpio_set_value+0x38/0xa4()
Modules linked in:
Backtrace:
[<c000c0ac>] (dump_backtrace+0x0/0x110) from [<c02c8278>] (dump_stack+0x18/0x1c)
r6:c0158fc8 r5:00000009 r4:00000000 r3:c03d4f70
[<c02c8260>] (dump_stack+0x0/0x1c) from [<c0019194>] (warn_slowpath_common+0x54/0x6c)
[<c0019140>] (warn_slowpath_common+0x0/0x6c) from [<c00191d0>] (warn_slowpath_null+0x24/0x2c)
r8:c38d5c00 r7:c03f82c0 r6:00000000 r5:000000d0 r4:c384e4fc
r3:00000009
[<c00191ac>] (warn_slowpath_null+0x0/0x2c) from [<c0158fc8>] (__gpio_set_value+0x38/0xa4)
[<c0158f90>] (__gpio_set_value+0x0/0xa4) from [<c0169b4c>] (corgi_bl_set_intensity+0x44/0x74)
r7:c3933418 r6:c3933400 r5:c392cdf0 r4:0000002f
[<c0169b08>] (corgi_bl_set_intensity+0x0/0x74) from [<c0169c1c>] (corgi_bl_update_status+0x5c/0x64)
r5:c03d31f0 r4:c3933400
[<c0169bc0>] (corgi_bl_update_status+0x0/0x64) from [<c02c3a68>] (corgi_lcd_probe+0x1a8/0x258)
r4:c392cdf0 r3:c0169bc0
[<c02c38c0>] (corgi_lcd_probe+0x0/0x258) from [<c01da7a4>] (spi_drv_probe+0x20/0x24)
r8:00000052 r7:c0192d9c r6:c03da6e8 r5:c38d5c34 r4:c38d5c00
[<c01da784>] (spi_drv_probe+0x0/0x24) from [<c0192c44>] (driver_probe_device+0xb0/0x208)
[<c0192b94>] (driver_probe_device+0x0/0x208) from [<c0192e0c>] (__driver_attach+0x70/0x94)
r6:c03da6e8 r5:c38d5c34 r4:c38d5c00 r3:00000000
[<c0192d9c>] (__driver_attach+0x0/0x94) from [<c0191268>] (bus_for_each_dev+0x54/0x90)
r6:c03da6e8 r5:c3827e80 r4:00000000 r3:00000000
[<c0191214>] (bus_for_each_dev+0x0/0x90) from [<c01927a4>] (driver_attach+0x20/0x28)
r7:00000000 r6:c03e29ec r5:c3932980 r4:c03da6e8
[<c0192784>] (driver_attach+0x0/0x28) from [<c0192340>] (bus_add_driver+0xd4/0x22c)
[<c019226c>] (bus_add_driver+0x0/0x22c) from [<c019335c>] (driver_register+0xa4/0x134)
r8:00000052 r7:c03ea900 r6:c03c32ac r5:c03bdfc8 r4:c03da6e8
[<c01932b8>] (driver_register+0x0/0x134) from [<c01db7ec>] (spi_register_driver+0x4c/0x60)
[<c01db7a0>] (spi_register_driver+0x0/0x60) from [<c03b3ce0>] (corgi_lcd_driver_init+0x14/0x1c)
[<c03b3ccc>] (corgi_lcd_driver_init+0x0/0x1c) from [<c000868c>] (do_one_initcall+0x9c/0x174)
[<c00085f0>] (do_one_initcall+0x0/0x174) from [<c02c1b94>] (kernel_init+0xf4/0x2a8)
[<c02c1aa0>] (kernel_init+0x0/0x2a8) from [<c0009270>] (ret_from_fork+0x14/0x24)
---[ end trace a863a63f242ee38c ]---
Akita machines have backlight controls hooked to a gpio expander chip,
max7310 using i2c transfers which can sleep.
In this case, pca953x_gpio_set_value() can be called to control
gpio, and pca953x_setup_gpio() sets can_sleep flag. Therefore,
gpio_set_value_cansleep() should be used in order to avoid WARN_ON on
akita machines.
Akita is the only exception in this case since other users of corgi_lcd
access backlight gpio controls through a different gpio expander
which does not set the can_sleep flag.
[jg1.han@...sung.com: used gpio_cansleep()]
Signed-off-by: Marko Katic <dromede@...il.com>
Signed-off-by: Jingoo Han <jg1.han@...sung.com>
---
Change since v3:
- remove redundant wording from commit message
Change since v2:
- use gpio_cansleep()
drivers/video/backlight/corgi_lcd.c | 17 +++++++++++++----
1 files changed, 13 insertions(+), 4 deletions(-)
diff --git a/drivers/video/backlight/corgi_lcd.c b/drivers/video/backlight/corgi_lcd.c
index e2e1b62..e5168f4 100644
--- a/drivers/video/backlight/corgi_lcd.c
+++ b/drivers/video/backlight/corgi_lcd.c
@@ -408,11 +408,20 @@ static int corgi_bl_set_intensity(struct corgi_lcd *lcd, int intensity)
/* Bit 5 via GPIO_BACKLIGHT_CONT */
cont = !!(intensity & 0x20) ^ lcd->gpio_backlight_cont_inverted;
- if (gpio_is_valid(lcd->gpio_backlight_cont))
- gpio_set_value(lcd->gpio_backlight_cont, cont);
+ if (gpio_is_valid(lcd->gpio_backlight_cont)) {
+ if (gpio_cansleep(lcd->gpio_backlight_cont))
+ gpio_set_value_cansleep(lcd->gpio_backlight_cont, cont);
+ else
+ gpio_set_value(lcd->gpio_backlight_cont, cont);
+ }
- if (gpio_is_valid(lcd->gpio_backlight_on))
- gpio_set_value(lcd->gpio_backlight_on, intensity);
+ if (gpio_is_valid(lcd->gpio_backlight_on)) {
+ if (gpio_cansleep(lcd->gpio_backlight_on))
+ gpio_set_value_cansleep(lcd->gpio_backlight_on,
+ intensity);
+ else
+ gpio_set_value(lcd->gpio_backlight_on, intensity);
+ }
if (lcd->kick_battery)
lcd->kick_battery();
--
1.7.2.5
--
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