Subject: [PATCH 3/4] ALSA: pxa27x: ac97 controller driver requests gpio

From: [email-masked] (Mike Dunn)
Date: Mon, 07 Jan 2013 06:10:04 -0800

On 01/07/2013 01:36 AM, Igor Grinberg wrote:
> On 01/06/13 21:13, Mike Dunn wrote:
>> During initialization, the ac97 driver must obtain the gpio for the mfp that is
>> used by the ac97 controller as the AC97_nRESET line, or else gpiolib will issue
>> a warning and stack dump.  Gpiolib may change this to a hard error soon.  The
>> line is used during an ac97 warm reset for working around a hardware bug in the
>> controller.
>>
>> Tested on a palm treo 680 machine.
>>
>> Signed-off-by: Mike Dunn <[email-masked]>
>> ---
>>  sound/arm/pxa2xx-ac97-lib.c |   10 +++++++++-
>>  1 files changed, 9 insertions(+), 1 deletions(-)
>>
>> diff --git a/sound/arm/pxa2xx-ac97-lib.c b/sound/arm/pxa2xx-ac97-lib.c
>> index 1ecd0a66..416d2e3 100644
>> --- a/sound/arm/pxa2xx-ac97-lib.c
>> +++ b/sound/arm/pxa2xx-ac97-lib.c
>> @@ -18,6 +18,7 @@
>>  #include <linux/delay.h>
>>  #include <linux/module.h>
>>  #include <linux/io.h>
>> +#include <linux/gpio.h>
>>  
>>  #include <sound/ac97_codec.h>
>>  #include <sound/pxa2xx-lib.h>
>> @@ -344,7 +345,12 @@ int pxa2xx_ac97_hw_probe(struct platform_device *dev)
>>  	}
>>  
>>  	if (cpu_is_pxa27x()) {
>> -		/* Use GPIO 113 as AC97 Reset on Bulverde */
>> +		ret = gpio_request(reset_gpio, "pxa27x ac97 reset");
>> +		if (ret < 0) {
>> +			pr_err("%s: gpio_request() failed: %d\n",
>> +			       __func__, ret);
>> +			goto err_conf;
>> +		}
> 
> I think if we are fine with the request in the driver,
> then we should move the direction and value configuration also
> to the driver, but let the pxa27x_assert_ac97reset() only switch
> the AF.

Well, I won't make a fuss on this point, but with code that runs very
infrequently, I thought that the cost of a call to gpio_direction_output() was
worth the clarity and insurance.

Thanks,
Mike