Commit 60db1687 authored by Tam Nguyen's avatar Tam Nguyen Committed by Zheng Zengkai
Browse files

i2c: designware: Disable TX_EMPTY irq while waiting for block length byte

stable inclusion
from stable-v6.6.3
commit b382f69317efb2578ef327d3eb413ea983cac9e6
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I8LBQP

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=b382f69317efb2578ef327d3eb413ea983cac9e6



--------------------------------

commit e8183fa10c25c7b3c20670bf2b430ddcc1ee03c0 upstream.

During SMBus block data read process, we have seen high interrupt rate
because of TX_EMPTY irq status while waiting for block length byte (the
first data byte after the address phase). The interrupt handler does not
do anything because the internal state is kept as STATUS_WRITE_IN_PROGRESS.
Hence, we should disable TX_EMPTY IRQ until I2C DesignWare receives
first data byte from I2C device, then re-enable it to resume SMBus
transaction.

It takes 0.789 ms for host to receive data length from slave.
Without the patch, i2c_dw_isr() is called 99 times by TX_EMPTY interrupt.
And it is none after applying the patch.

Cc: stable@vger.kernel.org
Co-developed-by: default avatarChuong Tran <chuong@os.amperecomputing.com>
Signed-off-by: default avatarChuong Tran <chuong@os.amperecomputing.com>
Signed-off-by: default avatarTam Nguyen <tamnguyenchi@os.amperecomputing.com>
Acked-by: default avatarJarkko Nikula <jarkko.nikula@linux.intel.com>
Reviewed-by: default avatarSerge Semin <fancer.lancer@gmail.com>
Signed-off-by: default avatarWolfram Sang <wsa@kernel.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: default avatarZheng Zengkai <zhengzengkai@huawei.com>
parent dafd04cc
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