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omap: i2c: add a timeout to the busy waiting 

The errata 1.153 workaround is busy waiting on XUDF bit in interrupt
context, which may lead to kernel hangs. The problem can be reproduced
by running the bus with wrong (too high) speed.

Signed-off-by: Alexander Shishkin <virtuoso@slind.org>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Ben Dooks <ben-linux@fluff.org>
This commit is contained in:
Alexander Shishkin 2010-05-11 11:35:17 -07:00 committed by Ben Dooks
parent 2dd151ab27
commit e9f59b9c9b
1 changed files with 9 additions and 1 deletions
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10
drivers/i2c/busses/i2c-omap.c
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@ -763,17 +763,25 @@ omap_i2c_rev1_isr(int this_irq, void *dev_id)
*/
static int errata_omap3_1p153(struct omap_i2c_dev *dev, u16 *stat, int *err)
{
while (!(*stat & OMAP_I2C_STAT_XUDF)) {
unsigned long timeout = 10000;
while (--timeout && !(*stat & OMAP_I2C_STAT_XUDF)) {
if (*stat & (OMAP_I2C_STAT_NACK | OMAP_I2C_STAT_AL)) {
omap_i2c_ack_stat(dev, *stat & (OMAP_I2C_STAT_XRDY |
OMAP_I2C_STAT_XDR));
*err |= OMAP_I2C_STAT_XUDF;
return -ETIMEDOUT;
}
cpu_relax();
*stat = omap_i2c_read_reg(dev, OMAP_I2C_STAT_REG);
}
if (!timeout) {
dev_err(dev->dev, "timeout waiting on XUDF bit\n");
return 0;
}
return 0;
}