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SubjectRe: [PATCH v2] i2c: at91: Read all available bytes at once
On Thu, Apr 26, 2018 at 11:53:14AM +0200, David Engraf wrote:
> With FIFO enabled it is possible to read multiple bytes
> at once in the interrupt handler as long as RXRDY is
> set. This may also reduce the number of interrupts.
>
> This patch polls RXRDY and reads all available bytes at
> once.
>
> Signed-off-by: David Engraf <david.engraf@sysgo.com>
Acked-by: Ludovic Desroches <ludovic.desroches@microchip.com>

Thanks a lot David.

Regards

Ludovic

> ---
> drivers/i2c/busses/i2c-at91.c | 12 ++++++++++--
> 1 file changed, 10 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/i2c/busses/i2c-at91.c b/drivers/i2c/busses/i2c-at91.c
> index bfd1fdff64a9..9caee5b79eac 100644
> --- a/drivers/i2c/busses/i2c-at91.c
> +++ b/drivers/i2c/busses/i2c-at91.c
> @@ -518,8 +518,16 @@ static irqreturn_t atmel_twi_interrupt(int irq, void *dev_id)
> * the RXRDY interrupt first in order to not keep garbage data in the
> * Receive Holding Register for the next transfer.
> */
> - if (irqstatus & AT91_TWI_RXRDY)
> - at91_twi_read_next_byte(dev);
> + if (irqstatus & AT91_TWI_RXRDY) {
> + /*
> + * Read all available bytes at once by polling RXRDY usable w/ and w/o
> + * FIFO. With FIFO enabled we could also read RXFL and avoid polling
> + * RXRDY.
> + */
> + do {
> + at91_twi_read_next_byte(dev);
> + } while (at91_twi_read(dev, AT91_TWI_SR) & AT91_TWI_RXRDY);
> + }
>
> /*
> * When a NACK condition is detected, the I2C controller sets the NACK,
> --
> 2.14.1
>

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