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SubjectRe: [PATCH] i2c: at91: handle TXRDY interrupt spam
Hello Raag,

On Tue, Apr 23, 2019 at 01:06:48PM +0530, Raag Jadav wrote:
> External E-Mail
>
>
> Performing i2c write operation while SDA or SCL line is held
> or grounded by slave device, we go into infinite at91_twi_write_next_byte
> loop with TXRDY interrupt spam.

Sorry but I am not sure to have the full picture, the controller is in
slave or master mode?

SVREAD is only used in slave mode. When SVREAD is set, it means that a read
access is performed and your issue concerns the write operation.

Regards

Ludovic

>
> Signed-off-by: Raag Jadav <raagjadav@gmail.com>
> ---
> drivers/i2c/busses/i2c-at91.c | 6 +++++-
> 1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/i2c/busses/i2c-at91.c b/drivers/i2c/busses/i2c-at91.c
> index 3f3e8b3..b2f5fdb 100644
> --- a/drivers/i2c/busses/i2c-at91.c
> +++ b/drivers/i2c/busses/i2c-at91.c
> @@ -72,6 +72,7 @@
> #define AT91_TWI_TXCOMP BIT(0) /* Transmission Complete */
> #define AT91_TWI_RXRDY BIT(1) /* Receive Holding Register Ready */
> #define AT91_TWI_TXRDY BIT(2) /* Transmit Holding Register Ready */
> +#define AT91_TWI_SVREAD BIT(3) /* Slave Read */
> #define AT91_TWI_OVRE BIT(6) /* Overrun Error */
> #define AT91_TWI_UNRE BIT(7) /* Underrun Error */
> #define AT91_TWI_NACK BIT(8) /* Not Acknowledged */
> @@ -571,7 +572,10 @@ static irqreturn_t atmel_twi_interrupt(int irq, void *dev_id)
> at91_disable_twi_interrupts(dev);
> complete(&dev->cmd_complete);
> } else if (irqstatus & AT91_TWI_TXRDY) {
> - at91_twi_write_next_byte(dev);
> + if ((status & AT91_TWI_SVREAD) && (dev->buf_len == 0))
> + at91_twi_write(dev, AT91_TWI_IDR, AT91_TWI_TXRDY);
> + else
> + at91_twi_write_next_byte(dev);
> }
>
> /* catch error flags */
> --
> 2.7.4
>
>

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