Re: [PATCH 1/4] dt-bindings: nvmem: new optional property write-protect-gpios

From: Bartosz Golaszewski
Date: Fri Nov 22 2019 - 08:04:16 EST

pt., 22 lis 2019 o 13:53 Linus Walleij <linus.walleij@xxxxxxxxxx> napisaÅ(a):
> On Fri, Nov 22, 2019 at 1:47 PM Bartosz Golaszewski
> <bgolaszewski@xxxxxxxxxxxx> wrote:
> > what about the existing bindings for at24 that don't mandate the
> > active-low flag? I'm afraid this would break the support for this
> > specific chip or lead to code duplication if we had this in both nvmem
> > and at24 with different logic.
> Hm yeah I realized this when I read patches 3 & 4.
> I would to like this:
> 1. Add a new generic property
> writeprotect-gpios that mandates to use GPIO_ACTIVE_LOW
> and use this in the new example
> 2. Deprecate wp-gpios in the binding, keep it around but deprecated.

This is a pretty standard property though - for instance it is
documented in the main mmc binding and doesn't mandate GPIO_ACTIVE_LOW
either. I think this is because nobody says that the write-protect
line must always be driver low to be asserted - this is highly


> 3. Add a quirk to gpiolib-of in the manner of the other quirks there
> (like for SPI) so that if we are dealing with some EEPROM node
> like at24 and the flag is zero, tag on GPIO_ACTIVE_LOW on
> the descriptor.
> The driver will now handle the semantic of both cases
> with gpiolib-of providing a quirk for the old binding.
> This is how we solved this type of problem before.
> Yours,
> Linus Walleij