6.12-stable review patch. If anyone has any objections, please let me know.
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From: Wolfram Sang wsa+renesas@sang-engineering.com
[ Upstream commit 6ad30f7890423341f4b79329af1f9b9bb3cdec03 ]
This backend requests a NACK from the controller driver when it detects an error. If that request gets ignored from some reason, subsequent accesses will wrongly be handled OK. To fix this, an error now changes the state machine, so the backend will report NACK until a STOP condition has been detected. This make the driver more robust against controllers which will sadly apply the NACK not to the current byte but the next one.
Fixes: a8335c64c5f0 ("i2c: add slave testunit driver") Signed-off-by: Wolfram Sang wsa+renesas@sang-engineering.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/i2c/i2c-slave-testunit.c | 19 +++++++++++++++---- 1 file changed, 15 insertions(+), 4 deletions(-)
diff --git a/drivers/i2c/i2c-slave-testunit.c b/drivers/i2c/i2c-slave-testunit.c index 9fe3150378e86..7ae0c7902f670 100644 --- a/drivers/i2c/i2c-slave-testunit.c +++ b/drivers/i2c/i2c-slave-testunit.c @@ -38,6 +38,7 @@ enum testunit_regs {
enum testunit_flags { TU_FLAG_IN_PROCESS, + TU_FLAG_NACK, };
struct testunit_data { @@ -90,8 +91,10 @@ static int i2c_slave_testunit_slave_cb(struct i2c_client *client,
switch (event) { case I2C_SLAVE_WRITE_REQUESTED: - if (test_bit(TU_FLAG_IN_PROCESS, &tu->flags)) - return -EBUSY; + if (test_bit(TU_FLAG_IN_PROCESS | TU_FLAG_NACK, &tu->flags)) { + ret = -EBUSY; + break; + }
memset(tu->regs, 0, TU_NUM_REGS); tu->reg_idx = 0; @@ -99,8 +102,10 @@ static int i2c_slave_testunit_slave_cb(struct i2c_client *client, break;
case I2C_SLAVE_WRITE_RECEIVED: - if (test_bit(TU_FLAG_IN_PROCESS, &tu->flags)) - return -EBUSY; + if (test_bit(TU_FLAG_IN_PROCESS | TU_FLAG_NACK, &tu->flags)) { + ret = -EBUSY; + break; + }
if (tu->reg_idx < TU_NUM_REGS) tu->regs[tu->reg_idx] = *val; @@ -129,6 +134,8 @@ static int i2c_slave_testunit_slave_cb(struct i2c_client *client, * here because we still need them in the workqueue! */ tu->reg_idx = 0; + + clear_bit(TU_FLAG_NACK, &tu->flags); break;
case I2C_SLAVE_READ_PROCESSED: @@ -151,6 +158,10 @@ static int i2c_slave_testunit_slave_cb(struct i2c_client *client, break; }
+ /* If an error occurred somewhen, we NACK everything until next STOP */ + if (ret) + set_bit(TU_FLAG_NACK, &tu->flags); + return ret; }