linux-kernel - Re: [PATCH 1/2] cs5535-gpio: add AMD CS5535/CS5536 GPIO driver support

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Message-ID: <17be05570906111311s717f126cyd4edf0847b839eef@mail.gmail.com>
Date:	Thu, 11 Jun 2009 22:11:58 +0200
From:	Tobias Müller <Tobias_Mueller@...m.info>
To:	Andres Salomon <dilinger@...labora.co.uk>
Cc:	akpm@...ux-foundation.org, Randy Dunlap <randy.dunlap@...cle.com>,
	deepak@...top.org, Takashi Iwai <tiwai@...e.de>,
	linux-kernel@...r.kernel.org, linux-geode@...ts.infradead.org,
	jordan@...micpenguin.net, cjb@...top.org
Subject: Re: [PATCH 1/2] cs5535-gpio: add AMD CS5535/CS5536 GPIO driver 
	support

>>  #define DRV_NAME "cs5535-gpio"
>>  #define GPIO_BAR 1
>> +#define GPIO_DEFAULT_MASK 0x0B003C66
>
> Where does this mask of available GPIOs originate from?

I had a comment in my original patch:

/**
* Some GPIO pins
*  31-29,23 : reserved (always mask out)
*  28       : Power Button
*  26       : PME#
*  22-16    : LPC
*  14,15    : SMBus
*  9,8      : UART1
*  7        : PCI INTB
*  3,4      : UART2/DDC
*  2        : IDE_IRQ0
*  1        : AC_BEEP
*  0        : PCI INTA
*
* If a mask was not specified, be conservative and only allow:
*  1,2,5,6,10-13,24,25,27
*/

I'll add this in my patch to clear it out.

>> +     spin_lock_irqsave(&chip->lock, flags);
>> +
>> +     /* check if this pin is available */
>> +     if ((mask & (1 << offset)) == 0) {
>> +             printk(KERN_INFO DRV_NAME
>> +                    ": pin %u is not available (check mask)\n",
>> offset);
>> +             return -EINVAL;
>
> There's a locking error here; you really want to spin_unlock_irqrestore
> before returning.

Thanks.

>> +     /* disable output aux 1 & 2 on this pin */
>> +     __cs5535_gpio_clear(chip, offset, GPIO_OUTPUT_AUX1);
>> +     __cs5535_gpio_clear(chip, offset, GPIO_OUTPUT_AUX2);
>> +
>> +     /* disable input aux 1 on this pin */
>> +     __cs5535_gpio_clear(chip, offset, GPIO_INPUT_AUX1);
>> +
>> +     /* disable output */
>> +     __cs5535_gpio_clear(chip, offset, GPIO_OUTPUT_ENABLE);
>> +
>> +     /* enable input */
>> +     __cs5535_gpio_set(chip, offset, GPIO_INPUT_ENABLE);
>
> I don't think this is the right place for all of this.  Your earlier
> email mentioned disabling OUT_AUX{1,2} for outputs, and IN_AUX for
> inputs.  I'm fine with doing that here, but I don't see why you're also
> disabling output and enabling input by default.

I mentioned this in an ealier mail too. When I request the GPIO from
userspace the direction file always contains "in", so I thought
this is the standard direction after resetting as I should be in a
defined state after requesting. But I didn't found anything
about this in GPIO lib documentation, so I would be fine to change
this if there is any common default behavoir.

>> -             .ngpio = 28,
>> +             .ngpio = 32,
>
> Since GPIOs 29-31 aren't externally available, and 28 is
> unavailable anyways, shouldn't we just set ngpio to 28?
I thought that 32 is in consistency with the datasheet as it always
talks about 32 GPIO pins.
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