Re: [PATCH] [OMAP] GPIO Module disable if all pins inactive

[Nishanth Menon <nm@ti.com>]

Varadarajan, Charu Latha had written, on 10/23/2009 11:05 PM, the following:
>>>  #endif
>>> +     if (cpu_is_omap24xx() || cpu_is_omap34xx() || cpu_is_omap44xx()) {
>>> +             if (!bank->>gpio_status) {
>>> +                     ctrl = __raw_readl(bank->>base + OMAP24XX_GPIO_CTRL);
>>> +                     /* Module is enabled, clocks are not gated */
>>> +                     ctrl &= 0xFFFFFFFE;
>>> +                     __raw_writel(ctrl, bank->>base + OMAP24XX_GPIO_CTRL);
>>> +             }
>>> +             bank->>gpio_status |= 1 << offset;
>>> +     }
>> why do this every time a gpio is enabled? why not do this iff gpio was
>> never used before.. how about the following:
> The module is enabled only when gpio_status indicates that no GPIO 
> in that  module is currently active and the GPIO being requested is the 1st one 
> to be active in that module.
> Each module would be disabled in free() API when all GPIOs in a particular module 
> becomes inactive. The module is re-enabled in request() API when a GPIO is 
> requested from the module that was previously disabled.
Thanks.

>> if (!bank->>gpio_status && (cpu_is_omap24xx() || cpu_is_omap34xx() ||
>> cpu_is_omap44xx())) {
>>        u32 ctrl = __raw_readl(bank->>base + OMAP24XX_GPIO_CTRL);
>>        /* Module is enabled, clocks are not gated */
>>        ctrl &= 0xFFFFFFFE;
>>        __raw_writel(ctrl, bank->>base + OMAP24XX_GPIO_CTRL);
>> }
>> bank->>gpio_status |= 1 << offset;
> Why to touch gpio_status if not used (for other than 34xx/24xx/44xx cases)? 
either the gpio_status should be under a #ifdef for 34xx when defining 
or it should be usable by all. what it does now is do both.

my proposal is to allow gpio_status to be usable by ALL OMAPs -> maybe 
OMAP1 also could also use it.. I cannot comment - but it does look to 
have scope of usage beyond omap2/3/4 series?

-- 
Regards,
Nishanth Menon