Message ID | 1401786032-17818-1-git-send-email-valentin.longchamp@keymile.com |
---|---|
State | Accepted |
Headers | show |
On Tue, Jun 03, 2014 at 11:00:32AM +0200, Valentin Longchamp wrote: > The mpc_i2c_fixup function is called when the bus is not released by a > slave. The function generates 9 pulses that should lead the slave > to release the bus. > > The sequence that generates the pulses disables/enables the I2C module > that controls the blocked bus. We have found out on the P2041 SoC that > this could cause the CPU to hang (for a short delay). > > To avoid this, this patch introduces a read to the I2CDR register > between the re-enablement of the I2C module in master mode and its > returning to the slave mode instead of the delay (the final delay, > between the pulses is kept), as proposed in procedure from the P2041 > reference manual (16.6.2.3), and the other manuals from the mpc83xx and > mpc85xx families. > > Signed-off-by: Rainer Boschung <rainer.boschung@keymile.com> > Signed-off-by: Valentin Longchamp <valentin.longchamp@keymile.com> > Applied to for-next, thanks!
diff --git a/drivers/i2c/busses/i2c-mpc.c b/drivers/i2c/busses/i2c-mpc.c index f539163..6a32aa0 100644 --- a/drivers/i2c/busses/i2c-mpc.c +++ b/drivers/i2c/busses/i2c-mpc.c @@ -115,7 +115,7 @@ static void mpc_i2c_fixup(struct mpc_i2c *i2c) for (k = 9; k; k--) { writeccr(i2c, 0); writeccr(i2c, CCR_MSTA | CCR_MTX | CCR_MEN); - udelay(delay_val); + readb(i2c->base + MPC_I2C_DR); writeccr(i2c, CCR_MEN); udelay(delay_val << 1); }