linux-kernel - Re: [PATCH 3/5] mfd: axp20x: Allow multiple regulators

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Message-ID: <20241006234849.427682c7@minigeek.lan>
Date: Sun, 6 Oct 2024 23:48:49 +0100
From: Andre Przywara <andre.przywara@....com>
To: Chen-Yu Tsai <wens@...e.org>
Cc: Lee Jones <lee@...nel.org>, Rob Herring <robh@...nel.org>, Krzysztof
 Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, Liam
 Girdwood <lgirdwood@...il.com>, Mark Brown <broonie@...nel.org>,
 devicetree@...r.kernel.org, linux-sunxi@...ts.linux.dev,
 linux-kernel@...r.kernel.org, Martin Botka <martin.botka@...ainline.org>,
 Chris Morgan <macromorgan@...mail.com>
Subject: Re: [PATCH 3/5] mfd: axp20x: Allow multiple regulators

On Thu, 3 Oct 2024 23:19:16 +0800
Chen-Yu Tsai <wens@...e.org> wrote:

> On Thu, Oct 3, 2024 at 7:15 PM Andre Przywara <andre.przywara@....com> wrote:
> >
> > At the moment trying to register a second AXP chip makes the probe fail,
> > as some sysfs registration fails due to a duplicate name:
> >
> > ...
> > [    3.688215] axp20x-i2c 0-0035: AXP20X driver loaded
> > [    3.695610] axp20x-i2c 0-0036: AXP20x variant AXP323 found
> > [    3.706151] sysfs: cannot create duplicate filename '/bus/platform/devices/axp20x-regulator'
> > [    3.714718] CPU: 0 UID: 0 PID: 1 Comm: swapper/0 Not tainted 6.12.0-rc1-00026-g50bf2e2c079d-dirty #192
> > [    3.724020] Hardware name: Avaota A1 (DT)
> > [    3.728029] Call trace:
> > [    3.730477]  dump_backtrace+0x94/0xec
> > [    3.734146]  show_stack+0x18/0x24
> > [    3.737462]  dump_stack_lvl+0x80/0xf4
> > [    3.741128]  dump_stack+0x18/0x24
> > [    3.744444]  sysfs_warn_dup+0x64/0x80
> > [    3.748109]  sysfs_do_create_link_sd+0xf0/0xf8
> > [    3.752553]  sysfs_create_link+0x20/0x40
> > [    3.756476]  bus_add_device+0x64/0x104
> > [    3.760229]  device_add+0x310/0x760
> > [    3.763717]  platform_device_add+0x10c/0x238
> > [    3.767990]  mfd_add_device+0x4ec/0x5c8
> > [    3.771829]  mfd_add_devices+0x88/0x11c
> > [    3.775666]  axp20x_device_probe+0x70/0x184
> > [    3.779851]  axp20x_i2c_probe+0x9c/0xd8
> > ...
> >
> > This is because we use PLATFORM_DEVID_NONE for the mfd_add_devices()
> > call, which would number the child devices in the same 0-based way, even
> > for the second (or any other) instance.
> >
> > Use PLATFORM_DEVID_AUTO instead, which automatically assigns
> > non-conflicting device numbers.  
> 
> That's weird... I don't remember running into this when working on the A80,
> which had two albeit different AXP chips. That was a long time ago though.

So I tested this on a Cubieboard 4, and it works there either way,
with or without this patch. That's RSB instead of I2C, which honestly
shouldn't make much of a difference, but maybe the call path differs?

But since it still works, I think this patch is correct regardless.

Thanks,
Andre


> > Signed-off-by: Andre Przywara <andre.przywara@....com>  
> 
> Reviewed-by: Chen-Yu Tsai <wens@...e.org>
> 
> > ---
> >  drivers/mfd/axp20x.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/mfd/axp20x.c b/drivers/mfd/axp20x.c
> > index 5ceea359289f..bc08ae433260 100644
> > --- a/drivers/mfd/axp20x.c
> > +++ b/drivers/mfd/axp20x.c
> > @@ -1419,7 +1419,7 @@ int axp20x_device_probe(struct axp20x_dev *axp20x)
> >                 }
> >         }
> >
> > -       ret = mfd_add_devices(axp20x->dev, -1, axp20x->cells,
> > +       ret = mfd_add_devices(axp20x->dev, PLATFORM_DEVID_AUTO, axp20x->cells,
> >                               axp20x->nr_cells, NULL, 0, NULL);
> >
> >         if (ret) {
> > --
> > 2.25.1
> >  
>