linux-kernel - Re: [PATCH 2/5] gpio: davinci: Use dev name for label and automatic base selection

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Date:   Thu, 6 Sep 2018 19:46:20 +0530
From:   Keerthy <j-keerthy@...com>
To:     Linus Walleij <linus.walleij@...aro.org>
CC:     "Andrew F. Davis" <afd@...com>, "Nori, Sekhar" <nsekhar@...com>,
        Kevin Hilman <khilman@...nel.org>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/5] gpio: davinci: Use dev name for label and automatic
 base selection



On Wednesday 05 September 2018 04:07 PM, Linus Walleij wrote:
> On Mon, Sep 3, 2018 at 7:40 AM Keerthy <j-keerthy@...com> wrote:
>> On Saturday 01 September 2018 12:43 AM, Andrew F. Davis wrote:
>>> Use dev_name to get a unique label and use -1 for a base to get our
>>> selection automatically. We pull in all GPIOs per chip now so this
>>> does not have the effect of out of order labels like before.
>>>
>>> We do these both together so we can drop all the static data in one
>>> patch. This also lets us normalize the return paths as we don't need
>>> any cleanup after this change.
>>
>> echo 28 > /sys/class/gpio/export
>> / # echo 28 > /sys/class/gpi[   12.839205] export_store: invalid GPIO 28
>> o/export
>> echo 2 > /sys/class/gp[   22.165728] export_store: invalid GPIO 2
>> io/export
>> / # echo 1 > /sys/class/gp[   25.961392] export_store: invalid GPIO 1
>> io/export
>> / # echo 3 > /sys/class/gp[   29.981918] export_store: invalid GPIO 3
>> io/export
>>
>> Export fails with this patch. I am testing this on keystone-k2g-evm.
> 
> I think the GPIO got a new number didn't it?
> 
> Did you check the gpio file in debugfs to see which number
> it got.

Okay now its numbered differently:

cat /sys/class/gpio/gpiochip340/ngpio
144

cat /sys/class/gpio/gpiochip272/ngpio
68

So gpio bank2 and bank1 have different gpio numbers. Is that acceptable?

> 
> This is sadly the global numberspace that we are tying to
> get rid of (new apps/scripts should use the chardev).
> 
> Are there applications that rely on the sysfs ABI on DaVinci?
> 
> In that case base needs to be prerseved.
> 
> Yours,
> Linus Walleij
>