From: Jean Delvare <khali@linux-fr•org>
To: linuxppc-dev@ozlabs•org
Cc: Sylvain Munaut <tnt@246tNt•com>
Subject: [RFC] I2C-MPC: Fix up error handling
Date: Fri, 9 Jun 2006 09:54:21 +0200 [thread overview]
Message-ID: <20060609095421.7157dc53.khali@linux-fr.org> (raw)
Hi all,
Could anyone please comment on this i2c-mpc patch, and give it some
testing on different systems? I'm fine with the error propagation
fixes, but less fine with the random resets being added, and rather
unhappy with the "retry once more just in case" thing, which I think,
if really needed, should instead be implemented using the standard
i2c_adapter.retries mechanism.
Thanks.
From: Kumar Gala <galak@kernel•crashing.org>
* If we have an Unfinished (MCF) or Arbitration Lost (MAL) error and
the bus is still busy reset the controller. This prevents the
controller from getting in a hung state for transactions for other
devices.
* Fixed up propogating the errors from i2c_wait.
Signed-off-by: Kumar Gala <galak@kernel•crashing.org>
Cc: Jean Delvare <khali@linux-fr•org>
Cc: Greg KH <greg@kroah•com>
Signed-off-by: Andrew Morton <akpm@osdl•org>
---
drivers/i2c/busses/i2c-mpc.c | 43 +++++++++++++++++++++++----------
1 file changed, 31 insertions(+), 12 deletions(-)
diff -puN drivers/i2c/busses/i2c-mpc.c~i2c-mpc-fix-up-error-handling drivers/i2c/busses/i2c-mpc.c
--- devel/drivers/i2c/busses/i2c-mpc.c~i2c-mpc-fix-up-error-handling 2006-06-01 20:22:55.000000000 -0700
+++ devel-akpm/drivers/i2c/busses/i2c-mpc.c 2006-06-01 20:22:55.000000000 -0700
@@ -115,11 +115,20 @@ static int i2c_wait(struct mpc_i2c *i2c,
if (!(x & CSR_MCF)) {
pr_debug("I2C: unfinished\n");
+
+ /* reset the controller if the bus is still busy */
+ if (x & CSR_MBB)
+ writeccr(i2c, 0);
+
return -EIO;
}
if (x & CSR_MAL) {
pr_debug("I2C: MAL\n");
+
+ /* reset the controller if the bus is still busy */
+ if (x & CSR_MBB)
+ writeccr(i2c, 0);
return -EIO;
}
@@ -160,7 +169,7 @@ static void mpc_i2c_stop(struct mpc_i2c
static int mpc_write(struct mpc_i2c *i2c, int target,
const u8 * data, int length, int restart)
{
- int i;
+ int i, ret;
unsigned timeout = i2c->adap.timeout;
u32 flags = restart ? CCR_RSTA : 0;
@@ -172,15 +181,17 @@ static int mpc_write(struct mpc_i2c *i2c
/* Write target byte */
writeb((target << 1), i2c->base + MPC_I2C_DR);
- if (i2c_wait(i2c, timeout, 1) < 0)
- return -1;
+ ret = i2c_wait(i2c, timeout, 1);
+ if (ret < 0)
+ return ret;
for (i = 0; i < length; i++) {
/* Write data byte */
writeb(data[i], i2c->base + MPC_I2C_DR);
- if (i2c_wait(i2c, timeout, 1) < 0)
- return -1;
+ ret = i2c_wait(i2c, timeout, 1);
+ if (ret < 0)
+ return ret;
}
return 0;
@@ -190,7 +201,7 @@ static int mpc_read(struct mpc_i2c *i2c,
u8 * data, int length, int restart)
{
unsigned timeout = i2c->adap.timeout;
- int i;
+ int i, ret;
u32 flags = restart ? CCR_RSTA : 0;
/* Start with MEN */
@@ -201,8 +212,9 @@ static int mpc_read(struct mpc_i2c *i2c,
/* Write target address byte - this time with the read flag set */
writeb((target << 1) | 1, i2c->base + MPC_I2C_DR);
- if (i2c_wait(i2c, timeout, 1) < 0)
- return -1;
+ ret = i2c_wait(i2c, timeout, 1);
+ if (ret < 0)
+ return ret;
if (length) {
if (length == 1)
@@ -214,8 +226,9 @@ static int mpc_read(struct mpc_i2c *i2c,
}
for (i = 0; i < length; i++) {
- if (i2c_wait(i2c, timeout, 0) < 0)
- return -1;
+ ret = i2c_wait(i2c, timeout, 0);
+ if (ret < 0)
+ return ret;
/* Generate txack on next to last byte */
if (i == length - 2)
@@ -246,8 +259,13 @@ static int mpc_xfer(struct i2c_adapter *
return -EINTR;
}
if (time_after(jiffies, orig_jiffies + HZ)) {
- pr_debug("I2C: timeout\n");
- return -EIO;
+ writeccr(i2c, 0);
+
+ /* try one more time before we error */
+ if (readb(i2c->base + MPC_I2C_SR) & CSR_MBB) {
+ pr_debug("I2C: timeout\n");
+ return -EIO;
+ }
}
schedule();
}
@@ -325,6 +343,7 @@ static int fsl_i2c_probe(struct platform
goto fail_irq;
}
+ writeccr(i2c, 0);
mpc_i2c_setclock(i2c);
platform_set_drvdata(pdev, i2c);
_
--
Jean Delvare
next reply other threads:[~2006-06-09 7:54 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-06-09 7:54 Jean Delvare [this message]
2006-07-30 11:14 ` [RFC] I2C-MPC: Fix up error handling Jean Delvare
2006-07-30 16:23 ` Kumar Gala
2006-07-31 6:57 ` Jean Delvare
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20060609095421.7157dc53.khali@linux-fr.org \
--to=khali@linux-fr$(echo .)org \
--cc=linuxppc-dev@ozlabs$(echo .)org \
--cc=tnt@246tNt$(echo .)com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox