[PATCH] mmc: pwrseq_simple: Fix regression with optional GPIOs

[Javier Martinez Canillas]

Hello Tony,

On 12/07/2015 09:32 PM, Tony Lindgren wrote:
> * Ulf Hansson <ulf.hansson at linaro.org> [151207 16:20]:
>> +Linus
>>
>> On 7 December 2015 at 23:54, Tony Lindgren <tony at atomide.com> wrote:
>>> Commit ce037275861e ("mmc: pwrseq_simple: use GPIO descriptors array API")
>>> changed the handling MMC power sequence so GPIOs no longer are optional.
>>>
>>> This broke SDIO WLAN at least for omap5 that can't yet use the reset GPIOs
>>> with pwrseq_simple as a wait is needed after enabling the SDIO device.
>>
>> Can you elaborate on this. Did it break omap5 or not? :-)
> 
> Yes it broke WLAN for omap5 that I just got fixed.. It only uses the clocks
> art of the pwrseq currently because of the delay needed.
> 
>> Also, I am interested to know more about the waiting period you need.
>> I assume that's because of the HW's characteristic?
> 
> At least TI wl12xx and Marvell 8787 need a delay after enabling the the WLAN.
> 
>> Why can't we have that being described in DT and then make
>> pwrseq_simple *wait* if needed?
> 
> We can, but I'm thinking that we might be better off adding support for
> regulators to pwrseq. Both TI wl12xx and Marvell 8787 get power from the
> battery, and probably have an integrated regulator.
> 
> Also, the delay and the power up sequencey can be more complicated than what
> we currently support. In the 8787 case, pdn pin needs to be asserted for 300ms
> after power pins are stable and while reset is held high.
> 
>>> Let's fix the problem by allocating the GPIO values array during init
>>> depending on the optional GPIOs found.
>>
>> Certainly it shall be optional! I wonder how I could let that patch
>> slip through, my bad!
>

I also wonder how I missed that in my patch, sorry for the mess :(
 
> OK good to hear :)
> 
>> Thanks for fixing this!
>

+1

> No problem, thanks,
> 
> Tony
> 

Best regards,
-- 
Javier Martinez Canillas
Open Source Group
Samsung Research America