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Commit 0d852fe4 authored by Ludovic Desroches's avatar Ludovic Desroches Committed by Wolfram Sang
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i2c: at91: fix SMBus quick command 



The driver claims to support SMBus quick command but it was not the
case. This patch fixes this issue. Without it, i2cdetect finds imaginary
devices. And with some IP versions, trying to send 0 byte can cause
issue when writing data to an EEPROM.

Signed-off-by: default avatarLudovic Desroches <ludovic.desroches@atmel.com>
Acked-by: default avatarJean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>

[wsa: improved the commit message]

Signed-off-by: default avatarWolfram Sang <w.sang@pengutronix.de>
parent 77b67063

drivers/i2c/busses/i2c-at91.c

+6 −1
Original line number Diff line number Diff line
@@ -39,6 +39,7 @@ 
#define	AT91_TWI_STOP		0x0002	/* Send a Stop Condition */

#define	AT91_TWI_MSEN		0x0004	/* Master Transfer Enable */

#define	AT91_TWI_SVDIS		0x0020	/* Slave Transfer Disable */

#define	AT91_TWI_QUICK		0x0040	/* SMBus quick command */

#define	AT91_TWI_SWRST		0x0080	/* Software Reset */



#define	AT91_TWI_MMR		0x0004	/* Master Mode Register */
@@ -212,7 +213,11 @@ static int at91_do_twi_transfer(struct at91_twi_dev *dev) 


	INIT_COMPLETION(dev->cmd_complete);

	dev->transfer_status = 0;

	if (dev->msg->flags & I2C_M_RD) {



	if (!dev->buf_len) {

		at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_QUICK);

		at91_twi_write(dev, AT91_TWI_IER, AT91_TWI_TXCOMP);

	} else if (dev->msg->flags & I2C_M_RD) {

		unsigned start_flags = AT91_TWI_START;



		if (at91_twi_read(dev, AT91_TWI_SR) & AT91_TWI_RXRDY) {