[PATCH] pinctrl: ocelot: Fix alt mode for ocelot

[PATCH] pinctrl: ocelot: Fix alt mode for ocelot

[Horatiu Vultur]

In case the driver was trying to set an alternate mode for gpio
0 or 32 then the mode was not set correctly. The reason is that
there is computation error inside the function ocelot_pinmux_set_mux
because in this case it was trying to shift to left by -1.
Fix this by actually shifting the function bits and not the position.

Fixes: 4b36082e2e09 ("pinctrl: ocelot: fix pinmuxing for pins after 31")
Signed-off-by: Horatiu Vultur <horatiu.vultur@microchip.com>
---
 drivers/pinctrl/pinctrl-ocelot.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/pinctrl/pinctrl-ocelot.c b/drivers/pinctrl/pinctrl-ocelot.c
index 29e4a6282a641..1dcbd0937ef5a 100644
--- a/drivers/pinctrl/pinctrl-ocelot.c
+++ b/drivers/pinctrl/pinctrl-ocelot.c
@@ -1204,7 +1204,7 @@ static int ocelot_pinmux_set_mux(struct pinctrl_dev *pctldev,
 	regmap_update_bits(info->map, REG_ALT(0, info, pin->pin),
 			   BIT(p), f << p);
 	regmap_update_bits(info->map, REG_ALT(1, info, pin->pin),
-			   BIT(p), f << (p - 1));
+			   BIT(p), (f >> 1) << p);
 
 	return 0;
 }
-- 
2.38.0

Re: [PATCH] pinctrl: ocelot: Fix alt mode for ocelot

[Andy Shevchenko]

On Mon, Feb 6, 2023 at 10:37 PM Horatiu Vultur
<horatiu.vultur@microchip.com> wrote:
>
> In case the driver was trying to set an alternate mode for gpio
> 0 or 32 then the mode was not set correctly. The reason is that
> there is computation error inside the function ocelot_pinmux_set_mux
> because in this case it was trying to shift to left by -1.
> Fix this by actually shifting the function bits and not the position.
>
> Fixes: 4b36082e2e09 ("pinctrl: ocelot: fix pinmuxing for pins after 31")
> Signed-off-by: Horatiu Vultur <horatiu.vultur@microchip.com>

...

>         regmap_update_bits(info->map, REG_ALT(0, info, pin->pin),
>                            BIT(p), f << p);
>         regmap_update_bits(info->map, REG_ALT(1, info, pin->pin),
> -                          BIT(p), f << (p - 1));
> +                          BIT(p), (f >> 1) << p);

I'm not sure I understand how this doesn't break anything that has a
bit 0 set in f. Is it not a problem?

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH] pinctrl: ocelot: Fix alt mode for ocelot

[Horatiu Vultur]

The 02/06/2023 22:59, Andy Shevchenko wrote:

Hi Andy,

> 
> On Mon, Feb 6, 2023 at 10:37 PM Horatiu Vultur
> <horatiu.vultur@microchip.com> wrote:
> >
> > In case the driver was trying to set an alternate mode for gpio
> > 0 or 32 then the mode was not set correctly. The reason is that
> > there is computation error inside the function ocelot_pinmux_set_mux
> > because in this case it was trying to shift to left by -1.
> > Fix this by actually shifting the function bits and not the position.
> >
> > Fixes: 4b36082e2e09 ("pinctrl: ocelot: fix pinmuxing for pins after 31")
> > Signed-off-by: Horatiu Vultur <horatiu.vultur@microchip.com>
> 
> ...
> 
> >         regmap_update_bits(info->map, REG_ALT(0, info, pin->pin),
> >                            BIT(p), f << p);
> >         regmap_update_bits(info->map, REG_ALT(1, info, pin->pin),
> > -                          BIT(p), f << (p - 1));
> > +                          BIT(p), (f >> 1) << p);
> 
> I'm not sure I understand how this doesn't break anything that has a
> bit 0 set in f. Is it not a problem?

I don't think it is a problem. This is similar to the implementation of
'lan966x_pinmux_set_mux', the only difference is that
lan966x_pinmux_set_mux has more GPIOs than ocelot.

If we take an example where f equals 0x1 and p equals 0.
REG_ALT(0): BIT(0) & (0x1 << 0) equals 0x1
REG_ALT(1): BIT(0) & ((0x1 >> 1) << 0)) equals 0x0.

Or am I misunderstood something?

> 
> --
> With Best Regards,
> Andy Shevchenko

-- 
/Horatiu

Re: [PATCH] pinctrl: ocelot: Fix alt mode for ocelot

[Horatiu Vultur]

The 02/07/2023 08:48, Horatiu Vultur wrote:
> The 02/06/2023 22:59, Andy Shevchenko wrote:

Hi,

Just a gentle ping about this patch.

I don't see anything that I should do, please let me know otherwise.
Thanks.

> 
> Hi Andy,
> 
> > 
> > On Mon, Feb 6, 2023 at 10:37 PM Horatiu Vultur
> > <horatiu.vultur@microchip.com> wrote:
> > >
> > > In case the driver was trying to set an alternate mode for gpio
> > > 0 or 32 then the mode was not set correctly. The reason is that
> > > there is computation error inside the function ocelot_pinmux_set_mux
> > > because in this case it was trying to shift to left by -1.
> > > Fix this by actually shifting the function bits and not the position.
> > >
> > > Fixes: 4b36082e2e09 ("pinctrl: ocelot: fix pinmuxing for pins after 31")
> > > Signed-off-by: Horatiu Vultur <horatiu.vultur@microchip.com>
> > 
> > ...
> > 
> > >         regmap_update_bits(info->map, REG_ALT(0, info, pin->pin),
> > >                            BIT(p), f << p);
> > >         regmap_update_bits(info->map, REG_ALT(1, info, pin->pin),
> > > -                          BIT(p), f << (p - 1));
> > > +                          BIT(p), (f >> 1) << p);
> > 
> > I'm not sure I understand how this doesn't break anything that has a
> > bit 0 set in f. Is it not a problem?
> 
> I don't think it is a problem. This is similar to the implementation of
> 'lan966x_pinmux_set_mux', the only difference is that
> lan966x_pinmux_set_mux has more GPIOs than ocelot.
> 
> If we take an example where f equals 0x1 and p equals 0.
> REG_ALT(0): BIT(0) & (0x1 << 0) equals 0x1
> REG_ALT(1): BIT(0) & ((0x1 >> 1) << 0)) equals 0x0.
> 
> Or am I misunderstood something?
> 
> > 
> > --
> > With Best Regards,
> > Andy Shevchenko
> 
> -- 
> /Horatiu

-- 
/Horatiu

Re: [PATCH] pinctrl: ocelot: Fix alt mode for ocelot

[Linus Walleij]

On Mon, Feb 6, 2023 at 9:37 PM Horatiu Vultur
<horatiu.vultur@microchip.com> wrote:

> In case the driver was trying to set an alternate mode for gpio
> 0 or 32 then the mode was not set correctly. The reason is that
> there is computation error inside the function ocelot_pinmux_set_mux
> because in this case it was trying to shift to left by -1.
> Fix this by actually shifting the function bits and not the position.
>
> Fixes: 4b36082e2e09 ("pinctrl: ocelot: fix pinmuxing for pins after 31")
> Signed-off-by: Horatiu Vultur <horatiu.vultur@microchip.com>

Patch applied for fixes.

Yours,
Linus Walleij