linux-kernel - Re: [PATCH] pinctrl: ocelot: Fix alt mode for ocelot

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Message-ID: <20230227203808.eqa5xmmldnx4lhop@soft-dev3-1>
Date:   Mon, 27 Feb 2023 21:38:08 +0100
From:   Horatiu Vultur <horatiu.vultur@...rochip.com>
To:     Andy Shevchenko <andy.shevchenko@...il.com>
CC:     <linux-gpio@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linus.walleij@...aro.org>, <alexandre.belloni@...tlin.com>
Subject: Re: [PATCH] pinctrl: ocelot: Fix alt mode for ocelot

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@...rochip.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@...rochip.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