From: "Jan Dąbroś" <jsd@semihalf.com>
To: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
linux-i2c <linux-i2c@vger.kernel.org>,
Jarkko Nikula <jarkko.nikula@linux.intel.com>,
Mika Westerberg <mika.westerberg@linux.intel.com>,
Hans de Goede <hdegoede@redhat.com>,
Wolfram Sang <wsa@kernel.org>,
Raul E Rangel <rrangel@chromium.org>,
Marcin Wojtas <mw@semihalf.com>,
Grzegorz Jaszczyk <jaz@semihalf.com>,
upstream@semihalf.com, Tom Lendacky <thomas.lendacky@amd.com>,
"Deucher, Alexander" <alexander.deucher@amd.com>,
"Easow, Nimesh" <Nimesh.Easow@amd.com>,
"Limonciello, Mario" <mario.limonciello@amd.com>,
kernel test robot <lkp@intel.com>
Subject: Re: [PATCH v2 2/2] i2c: designware: Add AMD PSP I2C bus support
Date: Wed, 2 Feb 2022 15:42:06 +0100 [thread overview]
Message-ID: <CAOtMz3OCTfp9UO6k81or_eSTn8zkVbP3P03R7Ha+3buNda28cw@mail.gmail.com> (raw)
In-Reply-To: <YffkwwxtZ/cul5CF@smile.fi.intel.com>
pon., 31 sty 2022 o 14:32 Andy Shevchenko
<andriy.shevchenko@linux.intel.com> napisał(a):
>
> On Mon, Jan 31, 2022 at 12:56:27PM +0100, Jan Dąbroś wrote:
> > pt., 28 sty 2022 o 16:50 Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> > napisał(a):
> > > On Fri, Jan 28, 2022 at 03:59:40PM +0100, Jan Dąbroś wrote:
> > > > pt., 28 sty 2022 o 15:48 Jan Dabros <jsd@semihalf.com> napisał(a):
>
> ...
>
> > > > > +struct psp_mbox {
> > > > > + u32 cmd_fields;
> > >
> > > > > + phys_addr_t i2c_req_addr;
> > >
> > > But phys_addr_t is platform-dependent type. Perhaps you meant to use u64
> > > here
> > > always?
> >
> > Once I remove the "depends on X86_64" I believe this should be left
> > platform-dependent.
>
> If it's a protocol or HW layout, it may not be platform-dependent.
Right you are correct, will keep this as 64bit variable.
>
> > > > > +} __packed;
>
> ...
>
> > > > > + if (psp_send_cmd(req))
> > >
> > > > > + return -EIO;
> > >
> > > Why is error code shadowed?
> > >
> >
> > Just as a side note - it wasn't modified in v2 when moving above to
> > psp_send_check_i2c_req(), but let me explain why I have introduced this
> > initially.
> >
> > We have two means of timeouts in the context of this driver:
> > 1. Timeout of internal mailbox, which means we cannot communicate with a
> > PSP for a programmed timeout. This timeout is encountered inside
> > psp_send_cmd().
> > 2. Timeout of i2c arbitration - which means that we can communicate with
> > PSP, but PSP refuses to release i2c bus for too long. This timeout is
> > returned by psp_send_i2c_req() in case of error.
> > (side note: both error conditions are very unlikely to happen at runtime)
> >
> > I wanted to clearly distinguish between these two and thus put all errors
> > around mailbox into "-EIO category", which is actually true.
>
> At very least this code needs more or less the above to be put as a comment.
ACK
>
> ...
>
> > > > > +cleanup:
> > > > > + mutex_unlock(&psp_i2c_access_mutex);
> > > > > + return 0;
> > >
> > > Not sure I understand why we ignore all above errors here.
> > >
> >
> > Actually we are not ignoring them, since each error sets "psp_i2c_mbox_fail
> > = true;". This means that if there is any error on x86-PSP interface, we
> > are ignoring i2c-arbitration and just fall back to normal (that is
> > no-quirk) operation.
> >
> > From the i2c-client perspective (who is eventually gathering error code
> > from above) I think we can claim that everything is fine, since bus is
> > granted to it. For developers there is an error message in case some debug
> > will be necessary.
>
> Perhaps needs a comment (sorry, if I overlooked it).
ACK.
>
> ...
>
> > > > > + if (!dev || !dev->dev)
> > > > > + return -ENODEV;
> > >
> > > At which circumstances may we get
> > > dev != NULL
> > > dev->dev == NULL
> > > ?
> > >
> > > ...
> > >
> > > > > if (!dev || !dev->dev)
> > > > > - return 0;
> > > > > + return -ENODEV;
> > >
> > > I see the same here, perhaps Hans knows the answer :-)
> >
> > Right, so I must admit that I simply used *-baytrail.c as a reference and
> > thinking that additional check shouldn't hurt us (always better than not
> > enough safety..). Looking more at this now - `dw_i2c_plat_probe()` will
> > boil-out earlier if `dev->dev == NULL`. Should I remove this extra check in
> > *-baytrail.c in the same commit?
>
> Maybe. Please, double check that it's not needed indeed.
Confirmed that this is unnecessary.
Best Regards,
Jan
>
> --
> With Best Regards,
> Andy Shevchenko
>
>
next prev parent reply other threads:[~2022-02-02 14:42 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-01-20 0:16 [PATCH 0/2] i2c-designware: Add support for AMD PSP semaphore Jan Dabros
2022-01-20 0:16 ` [PATCH 1/2] i2c: designware: Add missing locks Jan Dabros
2022-01-20 11:25 ` Hans de Goede
2022-01-24 10:33 ` Jan Dąbroś
2022-01-28 14:48 ` [PATCH v2 0/2] i2c-designware: Add support for AMD PSP semaphore Jan Dabros
2022-01-28 14:48 ` [PATCH v2 1/2] i2c: designware: Add missing locks Jan Dabros
2022-01-28 14:48 ` [PATCH v2 2/2] i2c: designware: Add AMD PSP I2C bus support Jan Dabros
2022-01-28 14:59 ` Jan Dąbroś
2022-01-28 15:49 ` Andy Shevchenko
2022-01-31 12:10 ` Jan Dąbroś
[not found] ` <CAOtMz3Oryr7mmRKf+secix_6=ZD_Lq+pMUoP=5T6AS6BPoqyQw@mail.gmail.com>
2022-01-31 13:31 ` Andy Shevchenko
2022-02-02 14:42 ` Jan Dąbroś [this message]
2022-01-28 14:58 ` [PATCH v2 0/2] i2c-designware: Add support for AMD PSP semaphore Jan Dąbroś
2022-02-02 14:43 ` [PATCH v3 " Jan Dabros
2022-02-02 14:43 ` [PATCH v3 2/2] i2c: designware: Add AMD PSP I2C bus support Jan Dabros
2022-02-02 16:13 ` Andy Shevchenko
2022-02-07 8:27 ` Jan Dąbroś
2022-02-07 11:41 ` Andy Shevchenko
2022-02-08 14:15 ` Jan Dąbroś
2022-02-07 14:25 ` Wolfram Sang
2022-02-08 14:13 ` Jan Dąbroś
2022-02-02 22:49 ` Limonciello, Mario
2022-02-03 10:41 ` Andy Shevchenko
2022-02-03 11:52 ` Jan Dąbroś
2022-01-20 0:16 ` [PATCH " Jan Dabros
2022-01-20 11:44 ` kernel test robot
2022-01-20 11:51 ` Hans de Goede
2022-01-21 9:59 ` Jan Dąbroś
2022-01-21 10:32 ` Hans de Goede
2022-01-21 17:38 ` Limonciello, Mario
2022-01-21 19:18 ` Tom Lendacky
2022-01-24 13:42 ` Jan Dąbroś
2022-01-26 19:36 ` Limonciello, Mario
2022-01-28 14:47 ` Jan Dąbroś
2022-01-24 12:35 ` Jan Dąbroś
2022-01-24 14:27 ` Hans de Goede
2022-01-20 14:20 ` Andy Shevchenko
2022-01-21 10:20 ` Jan Dąbroś
2022-01-21 17:51 ` Andy Shevchenko
2022-01-28 14:46 ` Jan Dąbroś
2022-01-20 15:33 ` kernel test robot
2022-01-20 17:09 ` Andy Shevchenko
2022-01-28 14:39 ` Jan Dąbroś
2022-01-20 11:15 ` [PATCH 0/2] i2c-designware: Add support for AMD PSP semaphore Hans de Goede
2022-01-20 12:29 ` Jan Dąbroś
2022-01-20 15:57 ` Hans de Goede
2022-01-21 10:27 ` Jan Dąbroś
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