Re: [PATCH 2/2] serial: mctrl_gpio: Support all GPIO suffixes (gpios vs gpio)

[Stefan Roese <sr@denx.de>]

Hi Geert,

On 12.08.19 13:17, Geert Uytterhoeven wrote:
> Hi Stefan,
> 
> On Thu, Aug 8, 2019 at 3:25 PM Stefan Roese <sr@denx.de> wrote:
>> This patch fixes a backward compatibility issue, when boards use the
>> old style GPIO suffix "-gpio" instead of the new "-gpios". This
>> potential problem has been introduced by commit d99482673f95 ("serial:
>> mctrl_gpio: Check if GPIO property exisits before requesting it").
>>
>> This patch now fixes this issue by iterating over all supported GPIO
>> suffixes by using the newly introduced for_each_gpio_suffix() helper.
>>
>> Also, the string buffer is now allocated on the stack to avoid the
>> problem of allocation in a loop and its potential failure.
>>
>> Signed-off-by: Stefan Roese <sr@denx.de>
> 
> Do we really need to spread this *-gpio" legacy support all over the kernel?
> 
> Seeing the only in-kernel users of legacy "rts-gpio" are
> 
>      arch/arm/boot/dts/am335x-nano.dts:      rts-gpio = <&gpio0 13
> GPIO_ACTIVE_HIGH>;
>      arch/arm/boot/dts/am335x-nano.dts:      rts-gpio = <&gpio2 15
> GPIO_ACTIVE_HIGH>;
>      arch/arm/boot/dts/am335x-pdu001.dts:    rts-gpio = <&gpio1 9
> GPIO_ACTIVE_HIGH>;
> 
> and this is handled by omap-serial.c, predating mctrl_gpio, I'd like to
> reconsider.
> 
> Documentation/devicetree/bindings/serial/serial.txt always described
> the "*-gpios"
> variants, so there should be no users of the legacy "*-gpio" variants.

Hmmm, you were the one to comment about supporting (not breaking) the
"-gpio" variant:

https://lkml.org/lkml/2019/6/24/248

That was my main motivation to work on this patch.

If we all agree, that only the documented "-gpios" variant needs to
be supported, then we can drop this patch.

Thanks,
Stefan