Alexander Shishkin said the following on 12/16/2009 07:32 PM:
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@xxxxxxxxx>
CC: linux-i2c@xxxxxxxxxxxxxxx
CC: linux-omap@xxxxxxxxxxxxxxx
---
drivers/i2c/busses/i2c-omap.c | 7 ++++++-
1 files changed, 6 insertions(+), 1 deletions(-)
diff --git a/drivers/i2c/busses/i2c-omap.c b/drivers/i2c/busses/i2c-omap.c
index ad8242a..b474c20 100644
--- a/drivers/i2c/busses/i2c-omap.c
+++ b/drivers/i2c/busses/i2c-omap.c
@@ -678,7 +678,9 @@ omap_i2c_rev1_isr(int this_irq, void *dev_id)
*/
static int omap3430_workaround(struct omap_i2c_dev *dev, u16 *stat, int *err)
{
- while (!(*stat & OMAP_I2C_STAT_XUDF)) {
+ unsigned long timeout = 10000;
+
+ while (!(*stat & OMAP_I2C_STAT_XUDF && --timeout)) {
a) timeout without using an actual delay is not a good idea - consider
each OPP - we can go upto 1ghz on 3630,
the actual time for 10000 iterations will depend on the MPU speed.
b) how did you arrive at the 10k iteration limit?
if (*stat & (OMAP_I2C_STAT_NACK | OMAP_I2C_STAT_AL)) {
omap_i2c_ack_stat(dev, *stat & (OMAP_I2C_STAT_XRDY |
OMAP_I2C_STAT_XDR));
@@ -689,6 +691,9 @@ static int omap3430_workaround(struct omap_i2c_dev *dev, u16 *stat, int *err)
*stat = omap_i2c_read_reg(dev, OMAP_I2C_STAT_REG);
}
+ if (!timeout)
+ dev_err(dev->dev, "timeout waiting on XUDF bit\n");
+
return 0;
}
Regards,
Nishanth Menon
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