Hi! I'm using Dell Inspiron 13, model P57G. It has a problem with the touchpad under Linux. Approximately half of the time, the touchpad is not working at all - the mouse cursor is not moving. In this case, there are error messages written to the kernel log every second: [ 53.127339] i2c_designware INT3433:00: controller timed out [ 54.219336] i2c_designware INT3433:00: controller timed out [ 55.311346] i2c_designware INT3433:00: controller timed out [ 56.403326] i2c_designware INT3433:00: controller timed out There is a simple fix - blacklist the driver (i2c_designware_platform). In this case, the touchpad words as a mouse and used IRQ 12. Googling for "blackist i2c_designware_platform" shows that I'm not the one using that approach. I started looking at the driver in git. A patch by Romain Baeriswyl applied on 2014-08-20 adds support for the "standard" mode with the 100kHz clock, as opposed to the 400kHz "fast" mode. Unfortunately, that patch only affects OpenFirmware systems, and I have ACPI. As soon as I set the clock to 100kHz, the touchpad started working every time. One fix would be to have a module parameter to force slower clock. It would still require users to deal with modprobe, so it's not optimal. I noticed that dev->get_clk_rate_khz(dev) returns 100000, but that would be 100000kHz = 100MHz. Not sure is somebody confused the units or it's the correct clock. Considering that I have no other systems to test, what would be the best approach? Set the clock to 100kHz for INT3433? Recognize Dell P57G system specifically? How? Preserve the original clock by reading the DW_IC_CON register and keeping some bits? Pavel -- 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
