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Commit 9656eeeb authored by Lars-Peter Clausen's avatar Lars-Peter Clausen Committed by Wolfram Sang
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i2c: Revert "i2c: xiic: Do not reset controller before every transfer" 



Commit d701667b ("i2c: xiic: Do not reset controller before every
transfer") removed the reinitialization of the controller before the start
of each transfer. Apparently this change is not safe to make and the commit
results in random I2C bus failures.

An easy way to trigger the issue is to run i2cdetect.

Without the patch applied:
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
	 00:          -- -- -- -- -- -- -- -- -- -- -- -- --
	 10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
	 20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
	 30: -- -- -- -- -- -- -- -- UU UU -- UU 3c -- -- UU
	 40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
	 50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
	 60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
	 70: -- -- -- -- -- -- -- --

With the patch applied every other or so invocation:
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
	 00:          03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f
	 10: 10 11 12 13 14 15 16 17 18 19 1a 1b 1c 1d 1e 1f
	 20: 20 21 22 23 24 25 26 27 28 29 2a 2b 2c 2d 2e 2f
	 30: -- -- -- -- -- -- -- -- UU UU -- UU 3c -- -- UU
	 40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
	 50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
	 60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
	 70: -- -- -- -- -- -- -- --

So revert the commit for now.

Fixes: d701667b ("i2c: xiic: Do not reset controller before every transfer")
Signed-off-by: default avatarLars-Peter Clausen <lars@metafoo.de>
Acked-by: default avatarShubhrajyoti Datta <shubhraj@xilinx.com>
Signed-off-by: default avatarWolfram Sang <wsa@the-dreams.de>
parent 8bb6fd58

drivers/i2c/busses/i2c-xiic.c

+3 −0
Original line number Diff line number Diff line
@@ -662,6 +662,9 @@ static void __xiic_start_xfer(struct xiic_i2c *i2c) 


static void xiic_start_xfer(struct xiic_i2c *i2c)

{

	spin_lock(&i2c->lock);

	xiic_reinit(i2c);

	spin_unlock(&i2c->lock);



	__xiic_start_xfer(i2c);

}