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To:     Jeshua Smith <jeshuas@nvidia.com>,
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Subject: RE: [PATCH V3] ACPI: APEI: Use ERST timeout for slow devices
Thread-Topic: [PATCH V3] ACPI: APEI: Use ERST timeout for slow devices
Thread-Index: AQHaCSXCfPnl8CyMXkanh9+ZGHddYLBeOodA
Date:   Fri, 27 Oct 2023 22:40:43 +0000
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References: <20231027223309.22883-1-jeshuas@nvidia.com>
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> Slow devices such as flash may not meet the default 1ms timeout value,
> so use the ERST max execution time value as the timeout if it is larger
> and if the ERST has the "slow" attribute set.
>
> Example:
> A NOR flash spec lists "Page program time (256 bytes)" as 120us typical,
> and 1800us max. A 32KB error log would be (32K/256) =3D 128 nor-flash
> pages. Writing those 128 nor-flash pages would then take
> 120us * 128 =3D 15ms typical, or 1800us * 128 =3D 230.4ms max.
>
> Without this change, when pstore calls APEI's ERST code to write a 32KB
> error log to the NOR flash in the example, the code will flag a timeout
> after 1ms and return an error to pstore. With this change, unless the
> max time value from the ERST table is exceeded, the code will not flag a
> timeout and will return success to pstore after the operation completes.
>
> Signed-off-by: Jeshua Smith <jeshuas@nvidia.com>

Reviewed-by: Tony Luck <tony.luck@intel.com>