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Message-ID: <68f1d8df-69d2-4246-8c64-4c7cc975feb1@moroto.mountain>
Date: Thu, 13 Jun 2024 21:34:44 +0300
From: Dan Carpenter <dan.carpenter@...aro.org>
To: Ben Walsh <ben@...nut.com>
Cc: Benson Leung <bleung@...omium.org>, Tzung-Bi Shih <tzungbi@...nel.org>,
Guenter Roeck <groeck@...omium.org>,
chrome-platform@...ts.linux.dev, linux-kernel@...r.kernel.org,
kernel-janitors@...r.kernel.org
Subject: Re: [PATCH] platform/chrome: cros_ec_lpc: Fix error code in
cros_ec_lpc_mec_read_bytes()
On Thu, Jun 13, 2024 at 07:20:32PM +0100, Ben Walsh wrote:
>
> Dan Carpenter <dan.carpenter@...aro.org> writes:
>
> > On Thu, Jun 13, 2024 at 05:51:39PM +0100, Ben Walsh wrote:
> >>
> >> Thanks for fixing this! Unfortunately `in_range` returns -EINVAL if
> >> length == 0 (see the definition of `fwk_ec_lpc_mec_in_range`). I'm sure
> >> this broke something in my testing, but I can't find what it was now.
> >
> > I don't think fwk_ec_lpc_mec_in_range() is upstream. This email is the
> > only reference I can find to it on the internet.
>
> Sorry, I mean cros_ec_lpc_mec_in_range().
>
> > int cros_ec_lpc_mec_in_range(unsigned int offset, unsigned int length)
> > {
> > if (length == 0)
> > - return -EINVAL;
> > + return 0;
> >
> > if (WARN_ON(mec_emi_base == 0 || mec_emi_end == 0))
> > return -EINVAL;
> >
> > But I don't like how subtle that is. Probably adding a check for
> > for if (length == 0) to the to cros_ec_lpc_mec_read_bytes() seems
> > like the best option. I guess option 2 is the best option.
>
> Thanks. I'll check out Tzung-Bi's suggestions as well before we decide.
Writing length 0 bytes to cros_ec_lpc_io_bytes_mec() changes the
function to basically this:
cros_ec_lpc_mec_lock();
/* Initialize I/O at desired address */
cros_ec_lpc_mec_emi_write_address(offset, access);
cros_ec_lpc_mec_unlock();
return 0;
I was a little concerned about the cros_ec_lpc_mec_emi_write_address()
But I don't know this subsystem at all so it might be fine.
Perhaps the cleanest thing is to delete the length == 0 check in
cros_ec_lpc_mec_in_range() and add one to the start of
cros_ec_lpc_io_bytes_mec().
I think that's a good solution.
regards,
dan carpenter
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