From 17ba1e87fca9e6bad7eacbb1ef042c83358d245e Mon Sep 17 00:00:00 2001 From: Jan Dabros Date: Fri, 18 Feb 2022 14:33:48 +0100 Subject: [PATCH] i2c: designware: Fix improper usage of readl Kernel test robot reported incorrect type in argument 1 of readl(), but more importantly it brought attention that MMIO accessor shouldn't be used in this case, since req->hdr.status is part of a command-response buffer in system memory. Since its value may be altered by PSP outside of the scope of current thread (somehow similar to IRQ handler case), we need to use READ_ONCE() to ensure compiler won't optimize this call. Fix also 'status' variable type to reflect that corresponding field in command-response buffer is platform-independent u32. Fixes: 78d5e9e299e3 ("i2c: designware: Add AMD PSP I2C bus support") Signed-off-by: Jan Dabros Reported-by: kernel test robot Reviewed-by: Andy Shevchenko Acked-by: Jarkko Nikula Signed-off-by: Wolfram Sang --- drivers/i2c/busses/i2c-designware-amdpsp.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/drivers/i2c/busses/i2c-designware-amdpsp.c b/drivers/i2c/busses/i2c-designware-amdpsp.c index 9d37becbd8463..3844695e6bf3e 100644 --- a/drivers/i2c/busses/i2c-designware-amdpsp.c +++ b/drivers/i2c/busses/i2c-designware-amdpsp.c @@ -160,9 +160,10 @@ static int psp_send_cmd(struct psp_i2c_req *req) /* Helper to verify status returned by PSP */ static int check_i2c_req_sts(struct psp_i2c_req *req) { - int status; + u32 status; - status = readl(&req->hdr.status); + /* Status field in command-response buffer is updated by PSP */ + status = READ_ONCE(req->hdr.status); switch (status) { case PSP_I2C_REQ_STS_OK: -- 2.30.2