From: Mika Westerberg <mika.westerberg@linux.intel.com>
To: Hans de Goede <hdegoede@redhat.com>
Cc: Wolfram Sang <wsa@the-dreams.de>,
linux-i2c@vger.kernel.org, linux-acpi@vger.kernel.org,
stable@vger.kernel.org
Subject: Re: [PATCH] i2c: core: ACPI: Properly set status byte to 0 for multi-byte writes
Date: Fri, 10 Aug 2018 15:35:24 +0300 [thread overview]
Message-ID: <20180810123524.GU2343@lahna.fi.intel.com> (raw)
In-Reply-To: <20180810122714.690-1-hdegoede@redhat.com>
On Fri, Aug 10, 2018 at 02:27:14PM +0200, Hans de Goede wrote:
> acpi_gsb_i2c_write_bytes() returns i2c_transfer()'s return value, which
> is the number of transfers executed on success, so 1.
>
> The ACPI code expects us to store 0 in gsb->status for success, not 1.
>
> Specifically this breaks the following code in the Thinkpad 8 DSDT:
>
> ECWR = I2CW = ECWR /* \_SB_.I2C1.BAT0.ECWR */
> If ((ECST == Zero))
> {
> ECRD = I2CR /* \_SB_.I2C1.I2CR */
> }
>
> Before this commit we set ECST to 1, causing the read to never happen
> breaking battery monitoring on the Thinkpad 8. Note the Thinkpad 8 also
> has some unrelated issues where i2c transfers are unreliable.
>
> This commit sets status to 0 if it was bigger then 0 (so success),
> mirroring the multi-byte read path, fixing this.
>
> Cc: stable@vger.kernel.org
> Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com>
next prev parent reply other threads:[~2018-08-10 12:35 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-08-10 12:27 [PATCH] i2c: core: ACPI: Properly set status byte to 0 for multi-byte writes Hans de Goede
2018-08-10 12:35 ` Mika Westerberg [this message]
2018-08-11 13:11 ` Wolfram Sang
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