From 7737eff01711b0de3cbc899eb569a66ddc2f5228 Mon Sep 17 00:00:00 2001 From: Robert Hancock Date: Tue, 4 Jun 2019 15:55:51 -0600 Subject: [PATCH] i2c: xiic: Add max_read_len quirk commit 49b809586730a77b57ce620b2f9689de765d790b upstream. This driver does not support reading more than 255 bytes at once because the register for storing the number of bytes to read is only 8 bits. Add a max_read_len quirk to enforce this. This was found when using this driver with the SFP driver, which was previously reading all 256 bytes in the SFP EEPROM in one transaction. This caused a bunch of hard-to-debug errors in the xiic driver since the driver/logic was treating the number of bytes to read as zero. Rejecting transactions that aren't supported at least allows the problem to be diagnosed more easily. Signed-off-by: Robert Hancock Reviewed-by: Michal Simek Signed-off-by: Wolfram Sang Cc: stable@kernel.org Signed-off-by: Greg Kroah-Hartman --- drivers/i2c/busses/i2c-xiic.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/drivers/i2c/busses/i2c-xiic.c b/drivers/i2c/busses/i2c-xiic.c index 0c51c0f..8d6b6ee 100644 --- a/drivers/i2c/busses/i2c-xiic.c +++ b/drivers/i2c/busses/i2c-xiic.c @@ -718,11 +718,16 @@ static const struct i2c_algorithm xiic_algorithm = { .functionality = xiic_func, }; +static const struct i2c_adapter_quirks xiic_quirks = { + .max_read_len = 255, +}; + static const struct i2c_adapter xiic_adapter = { .owner = THIS_MODULE, .name = DRIVER_NAME, .class = I2C_CLASS_DEPRECATED, .algo = &xiic_algorithm, + .quirks = &xiic_quirks, }; -- 2.7.4