On 07/12/12 02:18, Kevin Hilman wrote: > commit 97ee9f01d6 (ARM: OMAP: fix the ads7846 init code) mistakenly > frees the pen-down GPIO even though it will be used by the ads7846 > driver. But the driver requests the GPIO in ads7846_setup_pendown() method... > > Freeing a GPIO means that the GPIO bank containing that GPIO can be > runtime suspended if its the last/only GPIO being used in that bank. > If the GPIO bank is runtime suspended, any accesses to that bank will > cause faults. Unless, it is requested again, or am I missing something? > > Because the current code frees the GPIO, the ads7846 driver probe will > fault when it requests its IRQ line. But it requests that GPIO... in ads7846_setup_pendown() prior to requesting the IRQ... > Because the IRQ is a GPIO line, > the request IRQ will trickle down into the OMAP GPIO layer: > gpio_irq_type() --> _set_gpio_triggering() which can fault if the > bank has been runtime suspended. > > This is exctly what happens on Overo platforms (3530 Water, 3730 Overo > FireSTORM) since this is the only GPIO used in the bank. > > To fix, don't free the GPIO at all since it is always in use. > > Cc: Igor Grinberg <grinberg@xxxxxxxxxxxxxx> > Signed-off-by: Kevin Hilman <khilman@xxxxxx> > --- > Tony, this applies on top of your current fixes-non-critical branch and > should probably go in to v3.5-rc since the patch which introduced the > problem did as well. > > arch/arm/mach-omap2/common-board-devices.c | 3 --- > 1 file changed, 3 deletions(-) > > diff --git a/arch/arm/mach-omap2/common-board-devices.c b/arch/arm/mach-omap2/common-board-devices.c > index c187586..1ae6fd6 100644 > --- a/arch/arm/mach-omap2/common-board-devices.c > +++ b/arch/arm/mach-omap2/common-board-devices.c > @@ -84,9 +84,6 @@ void __init omap_ads7846_init(int bus_num, int gpio_pendown, int gpio_debounce, > ads7846_config.gpio_pendown = gpio_pendown; > } > > - if (!board_pdata || (board_pdata && !board_pdata->get_pendown_state)) > - gpio_free(gpio_pendown); > - > spi_register_board_info(&ads7846_spi_board_info, 1); > } > #else -- Regards, Igor. -- 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
