On Tue, Oct 07, 2008 at 11:28:52AM -0700, David Brownell wrote: > On Tuesday 07 October 2008, Aguirre Rodriguez, Sergio Alberto wrote: > > <1>Unable to handle kernel NULL pointer dereference at virtual address 00000000 > > Did you try with the hack I've sent, to work around one problematic > (and surprisingly reproducible!) i2c-omap timeout? Appended. > > Given I2C faults, many things blow up rudely ... hardly any I2C > drivers are written to tolerate transfer errors. Not entirely > unreasonably, since such errors are otherwise quite rare. > > > I currently suspect there's an issue where the i2c-omap code can > handle a bunch of requests that group closely together ... or are > separated by a lot of time ... but there's some middle ground > where if you wait the "right" amount of time before making the > next request, it times out instead of working correctly. > > I have no proof behind that theory, but it does seem to match up > to a few of the observed facts. Notably that the i2c timeouts > appear when the only device on that bus is the TWL4030, and the > drivers make known-to-be-valid requets ... the timeouts started > to appear only after some trivial changes in init timings, which > were caused by moving code out of drivers/i2c into directories > that are more appropriate. I was debugging the i2c-omap.c today but so far no clue why that i2c timeout is coming. It's really weird that it only fails on twl4030-usb (well, actually pwrirq and twl4030-usb fails since it can't request_irq). -- balbi -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
