Re: [PATCH v2 3/3] i2c: stm32: only send a STOP upon transfer completion

On 08/09/22, Patrick DELAUNAY wrote:

Hi,

On 9/8/22 12:59, Alain Volmat wrote:

...

Current function stm32_i2c_message_xfer is sending a STOP whatever the result of the transaction is. This can cause issues such as making the bus busy since the controller itself is already sending automatically a STOP when a NACK is generated. This can be especially seen when the processing get slower (ex: enabling lots of debug messages), ending up send 2 STOP (one automatically by the controller and a 2nd one at the end of the stm32_i2c_message_xfer function).

Cmon no need to thank me, that is kind of excessive :) Just the sign-off or codevelop tags for reference

if you can wait before merging I will test the series before monday

thanks Jorge

...

Thanks to Jorge Ramirez-Ortiz for diagnosing and proposing a first fix for this. [1]

[1] https://lore.kernel.org/u-boot/20220815145211.31342-2-jorge@foundries.io/

Reported-by: Jorge Ramirez-Ortiz, Foundries jorge@foundries.io Signed-off-by: Jorge Ramirez-Ortiz jorge@foundries.io Signed-off-by: Alain Volmat alain.volmat@foss.st.com

---

drivers/i2c/stm32f7_i2c.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/i2c/stm32f7_i2c.c b/drivers/i2c/stm32f7_i2c.c index 0ec67b5c12..8803979d3e 100644 --- a/drivers/i2c/stm32f7_i2c.c +++ b/drivers/i2c/stm32f7_i2c.c @@ -477,16 +477,16 @@ static int stm32_i2c_message_xfer(struct stm32_i2c_priv *i2c_priv, if (ret) break;

• 	/* End of transfer, send stop condition */
  

• 	mask = STM32_I2C_CR2_STOP;
  

• 	setbits_le32(&regs->cr2, mask);
  

• if (!stop)
  	/* Message sent, new message has to be sent */
  	return 0;
  

  } }

• /* End of transfer, send stop condition */
• mask = STM32_I2C_CR2_STOP;
• setbits_le32(&regs->cr2, mask);
• return stm32_i2c_check_end_of_message(i2c_priv); }

Reviewed-by: Patrick Delaunay patrick.delaunay@foss.st.com

Thanks Patrick