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Commit 540ac555 authored by Michael Hennerich's avatar Michael Hennerich Committed by Ben Dooks
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i2c-bfin-twi: handle faulty slave devices better 



Faulty slave devices might drive SDA low after a transfer finishes.  So,
when this scenario is detected, have the master generate up to 9 extra
clocks until the SDA is properly released.

Signed-off-by: default avatarMichael Hennerich <michael.hennerich@analog.com>
Signed-off-by: default avatarMike Frysinger <vapier@gentoo.org>
Signed-off-by: default avatarBen Dooks <ben-linux@fluff.org>
parent f878133b

drivers/i2c/busses/i2c-bfin-twi.c

+22 −0
Original line number Diff line number Diff line
@@ -20,6 +20,7 @@ 
#include <linux/completion.h>

#include <linux/interrupt.h>

#include <linux/platform_device.h>

#include <linux/delay.h>



#include <asm/blackfin.h>

#include <asm/portmux.h>
@@ -159,6 +160,27 @@ static void bfin_twi_handle_interrupt(struct bfin_twi_iface *iface, 
		if (mast_stat & BUFWRERR)

			dev_dbg(&iface->adap.dev, "Buffer Write Error\n");



		/* Faulty slave devices, may drive SDA low after a transfer

		 * finishes. To release the bus this code generates up to 9

		 * extra clocks until SDA is released.

		 */



		if (read_MASTER_STAT(iface) & SDASEN) {

			int cnt = 9;

			do {

				write_MASTER_CTL(iface, SCLOVR);

				udelay(6);

				write_MASTER_CTL(iface, 0);

				udelay(6);

			} while ((read_MASTER_STAT(iface) & SDASEN) && cnt--);



			write_MASTER_CTL(iface, SDAOVR | SCLOVR);

			udelay(6);

			write_MASTER_CTL(iface, SDAOVR);

			udelay(6);

			write_MASTER_CTL(iface, 0);

		}



		/* If it is a quick transfer, only address without data,

		 * not an err, return 1.

		 */