On May 26, 2009, at 3:22 AM, Fredrik Arnerup wrote:
We've had some trouble with I2C not working after a soft reboot,
which we think is due to the the erratum "I2C1" which is present in
at least the mpc8540 and the mpc8560. Since there is no good
workaround,
the only choice seems to be to avoid resetting the CPU while the I2C
bus is
busy.
The problem seems to be that the i2c-mpc driver leaves I2C in a busy
state
when
it receives a signal (e.g. upon shutdown).
The code below is not meant as a patch, just me thinking aloud.
Thoughts?
/Fredrik Arnerup
[email protected]
Index: drivers/i2c/busses/i2c-mpc.c
===================================================================
--- drivers/i2c/busses/i2c-mpc.c (revision 6933)
+++ drivers/i2c/busses/i2c-mpc.c (working copy)
@@ -262,12 +262,14 @@
/* Allow bus up to 1s to become not busy */
while (readb(i2c->base + MPC_I2C_SR) & CSR_MBB) {
if (signal_pending(current)) {
- pr_debug("I2C: Interrupted\n");
- writeccr(i2c, 0);
+ printk(KERN_WARNING "I2C: Interrupted\n");
+ if (readb(i2c->base + MPC_I2C_SR) ==
+ (CSR_MCF | CSR_MBB | CSR_RXAK))
+ mpc_i2c_fixup(i2c);
return -EINTR;
}
if (time_after(jiffies, orig_jiffies + HZ)) {
- pr_debug("I2C: timeout\n");
+ printk(KERN_WARNING "I2C: mpc_xfer() timeout
\n");
if (readb(i2c->base + MPC_I2C_SR) ==
(CSR_MCF | CSR_MBB | CSR_RXAK))
mpc_i2c_fixup(i2c);
I don't think we should have the printk's. Its possible that we hit
the interrupted condition while using the i2c from user space.
- k
_______________________________________________
Linuxppc-dev mailing list
[email protected]
https://lists.ozlabs.org/listinfo/linuxppc-dev
