linux-kernel - Re: [PATCH v7 5/6] i2c: designware: Use PCI PSP driver for communication

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Message-ID: <CAOtMz3P5eCLZiQiPDs-iG6EdwLZHsNeEmSpPXFjJXcEBQ=retg@mail.gmail.com>
Date:   Fri, 31 Mar 2023 14:03:30 +0200
From:   Jan Dąbroś <jsd@...ihalf.com>
To:     Jarkko Nikula <jarkko.nikula@...ux.intel.com>
Cc:     Mario Limonciello <mario.limonciello@....com>,
        Grzegorz Bernacki <gjb@...ihalf.com>,
        Mark Hasemeyer <markhas@...omium.org>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        Felix Held <Felix.Held@....com>, linux-i2c@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v7 5/6] i2c: designware: Use PCI PSP driver for communication

pt., 31 mar 2023 o 13:53 Jarkko Nikula <jarkko.nikula@...ux.intel.com>
napisał(a):
>
> On 3/30/23 01:07, Mario Limonciello wrote:
> > Currently the PSP semaphore communication base address is discovered
> > by using an MSR that is not architecturally guaranteed for future
> > platforms.  Also the mailbox that is utilized for communication with
> > the PSP may have other consumers in the kernel, so it's better to
> > make all communication go through a single driver.
> >
> > Signed-off-by: Mario Limonciello <mario.limonciello@....com>
> > ---
> > v6->v7:
> >   * Also imply CRYPTO_DEV_CCP_DD to fix build errors
> >   * Fix error message acquire/release inversion
> > v5->v6:
> >   * Drop now unnecessary asm/msr.h header
> >   * Fix IS_REACHABLE
> >   * Drop tags
> >   * Fix status code handling for Cezanne
> > v4->v5:
> >   * Pick up tags
> > v3->v4:
> >   * Pick up tags
> > v1->v2:
> >   * Fix Kconfig to use imply
> >   * Use IS_REACHABLE
> > ---
> >   drivers/i2c/busses/Kconfig                  |   3 +-
> >   drivers/i2c/busses/i2c-designware-amdpsp.c  | 177 +++-----------------
> >   drivers/i2c/busses/i2c-designware-core.h    |   1 -
> >   drivers/i2c/busses/i2c-designware-platdrv.c |   1 -
> >   include/linux/psp-platform-access.h         |   1 +
> >   5 files changed, 29 insertions(+), 154 deletions(-)
> >
> One note below in case there is a need to have another version of if you
> want. Not a show stopper for this.
>
> Acked-by: Jarkko Nikula <jarkko.nikula@...ux.intel.com>
>
> > @@ -214,7 +95,7 @@ static int psp_send_i2c_req(enum psp_i2c_req_type i2c_req_type)
> >       if (ret) {
> >               dev_err(psp_i2c_dev, "Timed out waiting for PSP to %s I2C bus\n",
> >                       (i2c_req_type == PSP_I2C_REQ_ACQUIRE) ?
> > -                     "release" : "acquire");
> > +                     "acquire" : "release");
> >               goto cleanup;
> >       }
> >
> This looks like worth of being an own patch. Maybe even for the
> linux-stable. I think it's very useful to have an error message to show
> correct information what operation actually failed.

Msg here is "TImed out waiting for _PSP to_ %s I2C bus" - when x86
wants to ACQUIRE the bus (i2c_req_type == PSP_I2C_REQ_ACQUIRE) then
PSP needs to RELEASE it and vice versa. If you think logic here is not
straightforward and should be adjusted, then we need to change the
whole sentence.