Messages in this thread | | | Date | Mon, 13 Sep 2021 12:55:42 -0400 | From | Sasha Levin <> | Subject | Re: [PATCH AUTOSEL 5.14 088/252] i2c: i801: Fix handling SMBHSTCNT_PEC_EN |
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On Thu, Sep 09, 2021 at 03:13:20PM +0200, Jean Delvare wrote: >Hi Sascha, > >On Thu, 9 Sep 2021 07:38:22 -0400, Sasha Levin wrote: >> From: Heiner Kallweit <hkallweit1@gmail.com> >> >> [ Upstream commit a6b8bb6a813a6621c75ceacd1fa604c0229e9624 ] >> >> Bit SMBHSTCNT_PEC_EN is used only if software calculates the CRC and >> uses register SMBPEC. This is not supported by the driver, it supports >> hw-calculation of CRC only (using bit SMBAUXSTS_CRCE). The chip spec >> states the following, therefore never set bit SMBHSTCNT_PEC_EN. >> >> Chapter SMBus CRC Generation and Checking >> If the AAC bit is set in the Auxiliary Control register, the PCH >> automatically calculates and drives CRC at the end of the transmitted >> packet for write cycles, and will check the CRC for read cycles. It will >> not transmit the contents of the PEC register for CRC. The PEC bit must >> not be set in the Host Control register. If this bit is set, unspecified >> behavior will result. >> >> This patch is based solely on the specification and compile-tested only, >> because I have no PEC-capable devices. >> >> Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com> >> Tested-by: Jean Delvare <jdelvare@suse.de> >> Signed-off-by: Wolfram Sang <wsa@kernel.org> >> Signed-off-by: Sasha Levin <sashal@kernel.org> >> --- >> drivers/i2c/busses/i2c-i801.c | 27 +++++++++++---------------- >> 1 file changed, 11 insertions(+), 16 deletions(-) > >This patch fixes a theoretical problem nobody has ever complained >about. I don't think it makes sense to backport it to stable kernel >branches.
Sure, I'll drop it. Thanks.
-- Thanks, Sasha
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