On Mon, Jul 18, 2011 at 11:31 AM, Shubhrajyoti <shubhrajyoti@xxxxxx> wrote: > Hi Manuel, >> >> From: *Manuel Lauss* <manuel.lauss@xxxxxxxxxxxxxx >> <mailto:manuel.lauss@xxxxxxxxxxxxxx>> >> Date: Thu, Jul 14, 2011 at 2:26 PM >> Subject: [PATCH 3/4] i2c/au1550: increase timeout limit >> To: Linux-I2C <linux-i2c@xxxxxxxxxxxxxxx >> <mailto:linux-i2c@xxxxxxxxxxxxxxx>>, Ben Dooks <ben-linux@xxxxxxxxx >> <mailto:ben-linux@xxxxxxxxx>> >> Cc: Manuel Lauss <manuel.lauss@xxxxxxxxxxxxxx >> <mailto:manuel.lauss@xxxxxxxxxxxxxx>> >> >> >> The timeout waiting for various events to occur is tailored for >> a module clock of 50MHz. On the DB1300 board only 48MHz can be >> supplied to the i2c module, which results in the timeout aborting >> complex transfers to slaves slightly too early if they employ >> for example clock stretching. >> >> With this change the WM8731 codec on the DB1300 board is correctly >> detected and initialized. >> >> Signed-off-by: Manuel Lauss <manuel.lauss@xxxxxxxxxxxxxx >> <mailto:manuel.lauss@xxxxxxxxxxxxxx>> >> --- >> drivers/i2c/busses/i2c-au1550.c | 2 +- >> 1 files changed, 1 insertions(+), 1 deletions(-) >> >> diff --git a/drivers/i2c/busses/i2c-au1550.c >> b/drivers/i2c/busses/i2c-au1550.c >> index 98ee11a..36d1b29 100644 >> --- a/drivers/i2c/busses/i2c-au1550.c >> +++ b/drivers/i2c/busses/i2c-au1550.c >> @@ -344,7 +344,7 @@ i2c_au1550_probe(struct platform_device *pdev) >> ret = -EIO; >> goto out_map; >> } >> - priv->xfer_timeout = 200; >> + priv->xfer_timeout = 400; > > What is the unit of the timeout. If it is in usec then how is it dependent > on the clock > supplied to the i2c module. > > Am I missing something. It's used as a loop counter, with udelay()s in the various loops. On the DB1300 board I observed that the function "wait_master_done()" returns an error due to the loop counter reaching zero when accessing the WM8731; an adm1025 hwmon actually works without this patch. That timeout is more or less a safeguard against busy waiting forever on various event bits. Manuel -- To unsubscribe from this list: send the line "unsubscribe linux-i2c" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
