From 9563c809dc9eee0873cbae6aa662ad56fd498642 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Martin=20Povi=C5=A1er?= Date: Tue, 19 Jul 2022 16:31:43 +0800 Subject: [PATCH] i2c: pasemi: Wait for write xfers to finish MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit stable inclusion from stable-v5.10.112 commit 84837f43e56fc2594f07a49399667c467de527a3 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I5HL0X Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=84837f43e56fc2594f07a49399667c467de527a3 -------------------------------- commit bd8963e602c77adc76dbbbfc3417c3cf14fed76b upstream. Wait for completion of write transfers before returning from the driver. At first sight it may seem advantageous to leave write transfers queued for the controller to carry out on its own time, but there's a couple of issues with it: * Driver doesn't check for FIFO space. * The queued writes can complete while the driver is in its I2C read transfer path which means it will get confused by the raising of XEN (the 'transaction ended' signal). This can cause a spurious ENODATA error due to premature reading of the MRXFIFO register. Adding the wait fixes some unreliability issues with the driver. There's some efficiency cost to it (especially with pasemi_smb_waitready doing its polling), but that will be alleviated once the driver receives interrupt support. Fixes: beb58aa39e6e ("i2c: PA Semi SMBus driver") Signed-off-by: Martin PoviĊĦer Reviewed-by: Sven Peter Signed-off-by: Wolfram Sang Signed-off-by: Greg Kroah-Hartman Signed-off-by: Zheng Zengkai Acked-by: Xie XiuQi --- drivers/i2c/busses/i2c-pasemi.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/drivers/i2c/busses/i2c-pasemi.c b/drivers/i2c/busses/i2c-pasemi.c index 20f2772c0e79..2c909522f0f3 100644 --- a/drivers/i2c/busses/i2c-pasemi.c +++ b/drivers/i2c/busses/i2c-pasemi.c @@ -137,6 +137,12 @@ static int pasemi_i2c_xfer_msg(struct i2c_adapter *adapter, TXFIFO_WR(smbus, msg->buf[msg->len-1] | (stop ? MTXFIFO_STOP : 0)); + + if (stop) { + err = pasemi_smb_waitready(smbus); + if (err) + goto reset_out; + } } return 0; -- GitLab