From: Rob Herring <robh@kernel.org>
To: Andi Shyti <andi.shyti@kernel.org>
Cc: Chris Packham <chris.packham@alliedtelesis.co.nz>,
linux-i2c@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] i2c: mpc: Use of_property_read_reg() to parse "reg"
Date: Mon, 12 Jun 2023 15:26:57 -0600 [thread overview]
Message-ID: <CAL_Jsq+wcrOjh7+0c=mrg+Qz6dbhOUE-VEeQ4FoWC3Y7ENoyfQ@mail.gmail.com> (raw)
In-Reply-To: <20230612210826.gmgrwjyu2g7jrysh@intel.intel>
On Mon, Jun 12, 2023 at 3:08 PM Andi Shyti <andi.shyti@kernel.org> wrote:
>
> Hi Rob,
>
> On Mon, Jun 12, 2023 at 01:27:03PM -0600, Rob Herring wrote:
> > On Sat, Jun 10, 2023 at 3:36 AM Andi Shyti <andi.shyti@kernel.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@kernel.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?
>
> Because if a function can return an error, the error must be
> checked. Even if the property is "reg" and the binding says that
> it's required. Otherwise let's make those functions void.
Then every function should have a must_check annotation, but they
don't as the function is designed to work with optional properties
where we want to ignore errors.
> > The old code wasn't worried about of_get_property() returning
> > NULL on the same possible errors.
>
> Sure! Checking the error comes for free. The patch is fine as it
> is, mine was a little improvement I asked for. I can still ack
> it and add the error handling later myself :)
>
> > 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?
>
> In my view, every error needs to be checked as every error is
> unlikely to happen: it makes the code future proof and makes sure
> other components failure don't impact the normal functioning of
> this driver.
An error in this case is a bad DT. It's not the kernel's job to ensure
DT is correct. If it is, then it is doing a terrible job. The reason
we have dtschema is to ensure correctness.
Rob
next prev parent reply other threads:[~2023-06-12 21:27 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-06-09 18:30 [PATCH] i2c: mpc: Use of_property_read_reg() to parse "reg" Rob Herring
2023-06-10 9:36 ` Andi Shyti
2023-06-12 19:27 ` Rob Herring
2023-06-12 21:08 ` Andi Shyti
2023-06-12 21:26 ` Rob Herring [this message]
2023-06-14 8:36 ` Wolfram Sang
2023-06-21 16:44 ` Guenter Roeck
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