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Subject: Re: [PATCH 2/5] gpio: davinci: Use dev name for label and automatic
 base selection
To:     Keerthy <j-keerthy@ti.com>,
        Linus Walleij <linus.walleij@linaro.org>
CC:     "Andrew F. Davis" <afd@ti.com>, "Nori, Sekhar" <nsekhar@ti.com>,
        Kevin Hilman <khilman@kernel.org>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
References: <20180831191326.25106-1-afd@ti.com>
 <20180831191326.25106-2-afd@ti.com>
 <2a02c241-ac91-1bac-380d-122858bb03c3@ti.com>
 <CACRpkdYvNeKyfRf5Et5zC4=hcu9cfDubftRFRHtrKLN-5Snd1Q@mail.gmail.com>
 <040ce524-f6e2-81a2-68db-57a645de22ea@ti.com>
 <0e199aa3-2d9d-4e7d-af23-8523722f017a@ti.com>
 <7ffe6694-0bb1-d1ae-3d93-51f11a358cc0@ti.com>
From:   Grygorii Strashko <grygorii.strashko@ti.com>
Message-ID: <fe34f216-b07b-6ccd-eee8-8b571d630017@ti.com>
Date:   Mon, 10 Sep 2018 17:05:53 -0500
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On 09/09/2018 09:47 PM, Keerthy wrote:
> 
> 
> On Sunday 09 September 2018 01:11 AM, Grygorii Strashko wrote:
>>
>>
>> On 09/06/2018 09:16 AM, Keerthy wrote:
>>>
>>>
>>> On Wednesday 05 September 2018 04:07 PM, Linus Walleij wrote:
>>>> On Mon, Sep 3, 2018 at 7:40 AM Keerthy <j-keerthy@ti.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
>>
>> could you or Andrew provide content of /debug/gpio before/after?
>> And ls /sys/class/gpio/?
> 
> Output on K2G:
> 
> Before
> ======
> 
> cat /debug/gpio
> gpiochip1: GPIOs 0-143, parent: platform/2603000.gpio, davinci_gpio.0:
> 
> gpiochip2: GPIOs 144-211, parent: platform/260a000.gpio, davinci_gpio.1:
>   gpio-156 (                    |cd                  ) in  lo
> 
> gpiochip0: GPIOs 484-511, parent: platform/2620240.keystone_dsp_gpio,
> 2620240.keystone_dsp_gpio:
> 
>   ls /sys/class/gpio/
> export       gpiochip0    gpiochip144  gpiochip484  unexport
> 
> cat /sys/class/gpio/gpiochip0/label
> davinci_gpio.0
> 
> cat /sys/class/gpio/gpiochip144/label
> davinci_gpio.1
> 
> cat /sys/class/gpio/gpiochip144/ngpio
> 68
> / # cat /sys/class/gpio/gpiochip0/ngpio
> 144
> 
> 
> After
> =====
> 
>   cat /debug/gpio
> gpiochip2: GPIOs 272-339, parent: platform/260a000.gpio, 260a000.gpio:
>   gpio-284 (                    |cd                  ) in  lo
> 
> gpiochip1: GPIOs 340-483, parent: platform/2603000.gpio, 2603000.gpio:
> 
> gpiochip0: GPIOs 484-511, parent: platform/2620240.keystone_dsp_gpio,
> 2620240.keystone_dsp_gpio:
> 
> ls /sys/class/gpio/
> export       gpiochip272  gpiochip340  gpiochip484  unexport
> 
> 
> cat /sys/class/gpio/gpiochip340/label
> 2603000.gpio
> / # cat /sys/class/gpio/gpiochip272/label
> 260a000.gpio
> / # cat /sys/class/gpio/gpiochip272/label
> 
> cat /sys/class/gpio/gpiochip272/ngpio
> 68
> / # cat /sys/class/gpio/gpiochip340/ngpio
> 144
> 
> In the case of SoCs that support multiple instances of Davinci GPIO IPs
> it is harder to figure out the right gpio number to export.
> 

Just to clarify above for all:
- for the first registered gpio chip
- if base >= 0 then gpiolib: try allocate gpios [base, base + ngpio]
  else gpiolib: try allocate gpios [ARCH_NR_GPIOS - ngpio, ARCH_NR_GPIOS]

so for the "after" case we can see gpio chip base allocation in hi to low order


-- 
regards,
-grygorii