Messages in this thread | | | From | Ben Gardner <> | Subject | [PATCH 0/3] gpio: add gpio_set_direction | Date | Fri, 26 Feb 2010 17:26:23 -0600 |
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The OLPC uses a GPIO output to enable/disable the MIC input. The code uses gpio_get_value() to retrive the current MIC enabled status. Due to a recent fix to cs5535-gpio, that function returns the input value. Since the input is not enabled, the input value does not match the output. gpiolib doesn't currently have the ability to enable both input and output. Nor does gpiolib have the ability to retrieve the current output value.
There are several ways to fix this MIC problem. 1) keep track of the output value in the audio driver and do not use gpio_get_value().
2) add a new gpiolib function to retrieve the output value.
3) add a way to set the GPIO bidirectional, so the read retrieves the real value that the MIC circuitry would see.
Since the CS5535 GPIO pins has independant control of the input and output, I went with the last option.
This patchset merges the gpio_direction_input() and gpio_direction_output() function into gpio_set_direction(). The direction parameter is a bit field, so the direction can be one of none, in, out, inout. The cs5535-gpio driver is updated to support set_direction() and cs5535audio_olpc is updated to set the GPIO in bidirectional mode.
Ben Gardner (3): gpiolib: add gpio_set_direction() cs5535-gpio: Use set_direction OLPC: ALSA: fix cs5535audio's MIC GPIO to enable input
drivers/gpio/cs5535-gpio.c | 34 ++++----- drivers/gpio/gpiolib.c | 123 +++++++++++++++--------------- include/asm-generic/gpio.h | 6 ++ include/linux/gpio.h | 5 + sound/pci/cs5535audio/cs5535audio_olpc.c | 2 +- 5 files changed, 89 insertions(+), 81 deletions(-)
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