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

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Date:   Fri, 31 Mar 2023 14:53:38 +0300
From:   Jarkko Nikula <jarkko.nikula@...ux.intel.com>
To:     Mario Limonciello <mario.limonciello@....com>,
        Jan Dąbroś <jsd@...ihalf.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>
Cc:     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

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.