The current driver version does not work for me on SAMA5D2 SOC. I2C bus devices probing always returns good state, and as a result all addresses 0x01-0x7f are always present. After a some digging into the driver, I found that the NACK bit is not handled correctly. I also found another SAMA5D2-related patch in the kernel tree (1). The result is a complex patch for correct I2C bus operation on SAMA5D2 SOC. [1] https://squing.com/lander/squing.com/?l=linux-i2c&m=156382173106314&w=3&_=%2F%23wXPKnebvZEv31W5L%2FkOlGQ%3D%3D Signed-off-by: Alexander Shiyan <eagle.alexander923@xxxxxxxxx> --- drivers/i2c/busses/i2c-at91.c | 14 +++++++++----- 1 file changed, 9 insertions(+), 5 deletions(-) diff --git a/drivers/i2c/busses/i2c-at91.c b/drivers/i2c/busses/i2c-at91.c index dbc5aa4ddf..fb0a922a62 100644 --- a/drivers/i2c/busses/i2c-at91.c +++ b/drivers/i2c/busses/i2c-at91.c @@ -113,7 +113,8 @@ static void at91_twi_write(struct at91_twi_dev *dev, unsigned reg, unsigned val) static void at91_disable_twi_interrupts(struct at91_twi_dev *dev) { at91_twi_write(dev, AT91_TWI_IDR, - AT91_TWI_TXCOMP | AT91_TWI_RXRDY | AT91_TWI_TXRDY); + AT91_TWI_TXCOMP | AT91_TWI_RXRDY | + AT91_TWI_TXRDY | AT91_TWI_NACK); } static void at91_init_twi_bus(struct at91_twi_dev *dev) @@ -223,8 +224,10 @@ static void at91_twi_write_next_byte(struct at91_twi_dev *dev) at91_twi_write(dev, AT91_TWI_THR, *dev->buf); /* send stop when last byte has been written */ - if (--dev->buf_len == 0) + if (--dev->buf_len == 0) { at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_STOP); + at91_twi_write(dev, AT91_TWI_IDR, AT91_TWI_TXRDY); + } dev_dbg(dev->dev, "wrote 0x%x, to go %d\n", *dev->buf, dev->buf_len); @@ -276,7 +279,7 @@ static int at91_twi_wait_completion(struct at91_twi_dev *dev) dev->transfer_status |= status; - } while (!(at91_twi_read(dev, AT91_TWI_SR) & AT91_TWI_TXCOMP)); + } while (!(status & AT91_TWI_TXCOMP)); at91_disable_twi_interrupts(dev); @@ -311,11 +314,12 @@ static int at91_do_twi_transfer(struct at91_twi_dev *dev) at91_twi_write(dev, AT91_TWI_CR, start_flags); at91_twi_write(dev, AT91_TWI_IER, - AT91_TWI_TXCOMP | AT91_TWI_RXRDY); + AT91_TWI_TXCOMP | AT91_TWI_NACK | AT91_TWI_RXRDY); } else { at91_twi_write_next_byte(dev); at91_twi_write(dev, AT91_TWI_IER, - AT91_TWI_TXCOMP | AT91_TWI_TXRDY); + AT91_TWI_TXCOMP | AT91_TWI_NACK | + (dev->buf_len ? AT91_TWI_TXRDY : 0)); } ret = at91_twi_wait_completion(dev); -- 2.39.1
