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SubjectRe: [PATCH] i2c: stm32: Fixes multibyte transfer for STM32F4 I2C controller
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On 10/11/2017 01:53 PM, Radoslaw Pietrzyk wrote:
> Do not read data on RXNE but on BTF only due to HW
> synchronisation problems and NACKing read data too early.
> It was found during testing of stmpe811 touchscreen driver.
>

Would you mind to explain what is behind "hw sync issue" you've seen ?

> Signed-off-by: Radoslaw Pietrzyk <radoslaw.pietrzyk@gmail.com>
> ---
> drivers/i2c/busses/i2c-stm32f4.c | 11 +----------
> 1 file changed, 1 insertion(+), 10 deletions(-)
>
> diff --git a/drivers/i2c/busses/i2c-stm32f4.c b/drivers/i2c/busses/i2c-stm32f4.c
> index 4ec1084..86bcf4c 100644
> --- a/drivers/i2c/busses/i2c-stm32f4.c
> +++ b/drivers/i2c/busses/i2c-stm32f4.c
> @@ -409,16 +409,9 @@ static void stm32f4_i2c_handle_read(struct stm32f4_i2c_dev *i2c_dev)
> * So, here we just disable buffer interrupt in order to avoid another
> * system preemption due to RX not empty event.
> */
> - case 2:
> - case 3:
> + default:
> stm32f4_i2c_clr_bits(reg, STM32F4_I2C_CR2_ITBUFEN);
> break;
> - /*
> - * For N byte reception with N > 3 we directly read data register
> - * until N-2 data.
> - */
> - default:
> - stm32f4_i2c_read_msg(i2c_dev);
> }
> }
>
> @@ -470,8 +463,6 @@ static void stm32f4_i2c_handle_rx_done(struct stm32f4_i2c_dev *i2c_dev)
> */
> reg = i2c_dev->base + STM32F4_I2C_CR1;
> stm32f4_i2c_clr_bits(reg, STM32F4_I2C_CR1_ACK);
> - stm32f4_i2c_read_msg(i2c_dev);
> - break;
> default:
> stm32f4_i2c_read_msg(i2c_dev);
> }
>

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