Re: [PATCH v6 2/3] gpio: add a reusable generic gpio_chip using regmap

[Pierre-Louis Bossart]

> > > +ÂÂÂ /* if we have a direction register we need both input and
> > > output */
> > > +ÂÂÂ if ((config->reg_dir_out_base || config->reg_dir_in_base) &&
> > > +ÂÂÂÂÂÂÂ (!config->reg_dat_base || !config->reg_set_base))
> > > +ÂÂÂÂÂÂÂ return ERR_PTR(-EINVAL);
> > ÂThis failed for me since I didn't have the 'dat' base assigned. I
> > still can't figure out what 'dat' stands for...I just assigned it to
> > the same offset as the 'set' base but really don't understand what
> > this is supposed to do.
>
> DAT is the data register, aka input register, if the GPIO is in input
> mode.
>
> If I read the datasheet correctly you should use the following:
>
> PCM512x_GPIO_EN should be reg_dir_out_base
> PCM512x_GPIO_CONTROL_1 should be reg_set_base
> PCM512x_GPIN should be reg_dat_base
>
> no custom xlate necessary. GPIN looks a bit fishy in that datasheet:
>  Âhttp://www.ti.com/lit/ds/symlink/pcm5121.pdf?ts=1590684141147

ok, I updated that part - can't test it though with the boards I have, 
only output is supported.

> PCM512x_GPIO_OUTPUT_1..6 is pinmux control and shouldn't be part of
> the gpio-regmap. Your driver needs to take care of that.

yes, that's what I did.

> > > +
> > > +ÂÂÂ /* we don't support having both registers simultaneously for
> > > now */
> > > +ÂÂÂ if (config->reg_dir_out_base && config->reg_dir_in_base)
> > > +ÂÂÂÂÂÂÂ return ERR_PTR(-EINVAL);
> >
> > and this second test seems to contradict the notion of 'both input and
> > output' above?
>
> dir_out_base is used if the register is high active to select an output.
> dir_in_base is used for a low active register. Thus both bases are used
> to switch a GPIO between input and output.

ok, makes sense now, thanks for the explanations.

> > re-adding comment from previous series:
> > Â>> I still have a series of odd warnings I didn't have before: >> >>
> > [Â 101.400263] WARNING: CPU: 3 PID: 1129 at >>
> > drivers/gpio/gpiolib.c:4084 gpiod_set_value+0x3f/0x50 >> >> This seems
> > to come from >>ÂÂÂÂ /* Should be using gpiod_set_value_cansleep() */
> > > > ÂÂÂ WARN_ON(desc->gdev->chip->can_sleep); > > Right now,
> > gpio-regmap hardcodes can_sleep to true. But the only regmap > which
> > don't sleep is regmap-mmio. The PCM512x seems to be either I2C or >
> > SPI, which can both sleep. So this warning is actually correct and >
> > wherever this gpio is set should do it by calling the _cansleep() >
> > version.
> >
> > I still have the warnings with this version, not sure if you wanted to
> > fix it in the v6 or is this needs to be fixed in another piece of
> > code/patch. How would we go about removing this warning?
>
> There is no fix in gpio-regmap. wherever this GPIO is connected to must
> not call gpiod_set_value() but have to use gpiod_set_value_cansleep().

yes, I figured this out and corrected the drivers, works just fine now. 
My cleaned-up code is at 
https://github.com/thesofproject/linux/pull/1945, I'll resubmit the v2 
based on these patches when they are merged and available in Mark 
Brown's tree (and I need to address the clock-related feedback).

Thanks for your work Michael, really nice and useful, feel free to add 
the following tag:

Tested-by: Pierre-Louis Bossart <pierre-louis.bossart@xxxxxxxxxxxxxxx>