linux-kernel - Re: [PATCH] i2c: mpc: Use of_property_read

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Date:   Mon, 12 Jun 2023 13:27:03 -0600
From:   Rob Herring <robh@...nel.org>
To:     Andi Shyti <andi.shyti@...nel.org>
Cc:     Chris Packham <chris.packham@...iedtelesis.co.nz>,
        linux-i2c@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] i2c: mpc: Use of_property_read_reg() to parse "reg"

On Sat, Jun 10, 2023 at 3:36 AM Andi Shyti <andi.shyti@...nel.org> wrote:
>
> Hi Rob,
>
> On Fri, Jun 09, 2023 at 12:30:44PM -0600, Rob Herring wrote:
> > Use the recently added of_property_read_reg() helper to get the
> > untranslated "reg" address value.
> >
> > Signed-off-by: Rob Herring <robh@...nel.org>
> > ---
> >  drivers/i2c/busses/i2c-mpc.c | 5 +++--
> >  1 file changed, 3 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/i2c/busses/i2c-mpc.c b/drivers/i2c/busses/i2c-mpc.c
> > index cfd074ee6d54..595dce9218ad 100644
> > --- a/drivers/i2c/busses/i2c-mpc.c
> > +++ b/drivers/i2c/busses/i2c-mpc.c
> > @@ -316,9 +316,10 @@ static void mpc_i2c_setup_512x(struct device_node *node,
> >       if (node_ctrl) {
> >               ctrl = of_iomap(node_ctrl, 0);
> >               if (ctrl) {
> > +                     u64 addr;
> >                       /* Interrupt enable bits for i2c-0/1/2: bit 24/26/28 */
> > -                     pval = of_get_property(node, "reg", NULL);
> > -                     idx = (*pval & 0xff) / 0x20;
> > +                     of_property_read_reg(node, 0, &addr, NULL);
>
> because of_property_read_reg() can return error, can we check
> also the error value here?

Why? The old code wasn't worried about of_get_property() returning
NULL on the same possible errors. If anyone is still actually using
mpc512x, I don't think their DTB will have an error at this point.
IOW, is improving the error handling on this really worth it?

Rob