On Tue, Oct 30, 2018 at 12:51 PM Charles Keepax <ckeepax@xxxxxxxxxxxxxxxxxxxxx> wrote: > > On Mon, Oct 29, 2018 at 11:15:47AM +0100, Benjamin Tissoires wrote: > > On Sun, Oct 28, 2018 at 11:31 PM Wolfram Sang <wsa@xxxxxxxxxxxxx> wrote: > > > > > > On Fri, Oct 19, 2018 at 09:59:58AM +0100, Charles Keepax wrote: > > > > The IRQ will be mapped in i2c_device_probe only if client->irq is zero and > > > > i2c_device_remove does not clear this. When rebinding an I2C device, > > > > whos IRQ provider has also been rebound this means that an IRQ mapping > > > > will never be created, causing the I2C device to fail to acquire its > > > > IRQ. Fix this issue by clearing client->irq in i2c_device_remove, > > > > forcing i2c_device_probe to lookup the mapping again. > > > > > > > > Signed-off-by: Charles Keepax <ckeepax@xxxxxxxxxxxxxxxxxxxxx> > > > > > > Adding Benjamin here again. Also, should there be a Fixes: tag? > > > > Not sure if the circumstances are preventing me to think straight, but > > how can you reprobe the i2c_device? > > You just head into /sys/bus/i2c/drivers/<the_driver> and use the > unbind file to remove the driver. You can then probe the driver > again using the bind file. Right... not sure why I haven't seen that one yesterday > > > And in all cases, for the Host notify part, having the IRQ already set > > shouldn't be an issue. > > To be clear this isn't a theoretical issue this is something I > can replicate very easily. The problem comes in when you unbind > both the I2C device and the device that is providing its IRQ. In > my case the I2C device is a speaker amp and the device providing > IRQs is an audio CODEC. > > When the device providing the IRQ is unbound it will delete the > IRQ mapping. For the I2C device to acquire its IRQ something > needs to recreate that mapping, this would normally happen (in a > DT system) as a result of the of_irq_get/_by_name. But as > client->irq is already set this doesn't happen, causing the I2C > device to fail probe because it couldn't locate its IRQ. Right. I completely missed the fact that the driver of the IRQ could be reset during the period the device is unbound. That's a pretty strong case for this patch. > > I can provide some stack traces or something if that would help > to clarify the issue? No, that's fine. Now I get this, and I totally agree with the approach: Reviewed-by: Benjamin Tissoires <benjamin.tissoires@xxxxxxxxxx> Cheers, Benjamin
