Hi, On Mon, Nov 03, 2014 at 05:42:07PM +0200, Mika Westerberg wrote: > On Mon, Nov 03, 2014 at 05:27:43PM +0200, Mika Westerberg wrote: > > On Mon, Nov 03, 2014 at 09:00:48AM -0600, Felipe Balbi wrote: > > > On Mon, Nov 03, 2014 at 11:24:02AM +0200, Mika Westerberg wrote: > > > > On Fri, Oct 31, 2014 at 11:45:09AM -0700, David Cohen wrote: > > > > > > I think adding the module exit + allowing this driver to be a module > > > > > > would be a good approach. Then we don't need to force generic x86 kernel > > > > > > binaries to always have this driver. Unless Mathias or Mika knows a > > > > > > constraint to force this driver to be builtin only. > > > > > > > > > > It helps if I CC them when asking for feedback :) > > > > > > > > > > Mathias, Mika, do you know any constraint that forces pinctrl-baytrail > > > > > to be bool? > > > > > > > > The only constraint that has been keeping this driver as bool is that > > > > some machines like, Asus T100, uses ACPI GPIO operation regions for > > > > toggling GPIOs to get things like sensor hub powered on. The GPIO > > > > operation region code does not yet handle -EPROBE_DEFER so only way to > > > > ensure that the operation region is there is to have the driver compiled > > > > in to the kernel. > > > > > > But that's not enough excuse to have every single x86 in the market > > > shipping with this driver. Think about a distro kernel, most likely this > > > gets enabled and it's wrong in 80% of the cases. > > > > True, but see below. > > > > > It would be nicer to add EPROBE_DEFER support, convert this into > > > tristate and have default = M if BAYTRAIL, or something. > > > > If it were simple as that we would have done that already. Please check > > drivers/gpio/gpiolib-acpi.c:acpi_gpio_adr_space_handler() and tell me > > how we can do that. > > Actually the above is not the problem because we already have registered > the GPIO chip and hence we have the GPIO available to the firmware code. what happens before you registered the gpio chip ? It takes some time from head.S to gpiochip_irqchip_add(). Anywhere between that time, firmware could try to access gpios and the same problem would occur. > The real problem is that if the ACPI GPIO operation handler is not there > at the time firmware decides to do something it will just skip things > that depend on the operation region. So if it has a GPIO that is used to > turn on sensor hub or touch panel or whatever, this will not be done and > it results that the device in question might not work properly. that's an issue that needs solving, but forcing every x86 kernel to ship with this driver, is not a proper solution. -- balbi
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