[PATCH 1/1] gpio: omap: Fix bad device access with setup_irq()

[santosh shilimkar]

On 1/16/2015 2:50 PM, Tony Lindgren wrote:
> Similar to omap_gpio_irq_type() let's make sure that the GPIO
> is usable as an interrupt if the platform init code did not
> call gpio_request(). Otherwise we can get invalid device access
> after setup_irq():
>
I let Linus W comment on it but IIRC we chewed this issue last
time and the conclusion was the gpio_request() must have to be called
directly or indirectly in case of irq line.

One old thread on possibly similar issue is here[1]


> WARNING: CPU: 0 PID: 1 at drivers/bus/omap_l3_noc.c:147 l3_interrupt_handler+0x214/0x340()
> 44000000.ocp:L3 Custom Error: MASTER MPU TARGET L4CFG (Idle): Data Access in Supervisor mode during Functional access
> ...
> [<c05f21e4>] (__irq_svc) from [<c05f1974>] (_raw_spin_unlock_irqrestore+0x34/0x44)
> [<c05f1974>] (_raw_spin_unlock_irqrestore) from [<c00914a8>] (__setup_irq+0x244/0x530)
> [<c00914a8>] (__setup_irq) from [<c00917d4>] (setup_irq+0x40/0x8c)
> [<c00917d4>] (setup_irq) from [<c0039c8c>] (omap_system_dma_probe+0x1d4/0x2b4)
> [<c0039c8c>] (omap_system_dma_probe) from [<c03b2200>] (platform_drv_probe+0x44/0xa4)
> ...
>
> We can fix this the same way omap_gpio_irq_type() is handling it.
>
> Note that the long term solution is to change the gpio-omap driver
> to handle the banks as separate driver instances. This will allow
> us to rely on just runtime PM for tracking the bank specific state.
>
> Reported-by: Russell King <rmk+kernel at arm.linux.org.uk>
> Cc: Felipe Balbi <balbi at ti.com>
> Cc: Javier Martinez Canillas <javier at dowhile0.org>
> Cc: Kevin Hilman <khilman at kernel.org>
> Cc: Linus Walleij <linus.walleij at linaro.org>
> Cc: Russell King - ARM Linux <linux at arm.linux.org.uk>
> Cc: Santosh Shilimkar <ssantosh at kernel.org>
> Signed-off-by: Tony Lindgren <tony at atomide.com>
> ---
>   drivers/gpio/gpio-omap.c | 39 +++++++++++++++++++++++++++++++++------
>   1 file changed, 33 insertions(+), 6 deletions(-)
>
Is it really OMAP specific issue ? On OMAP, clocks needs to enabled for 
GPIO's to work which is what the init is doing but I believe the same
should apply to other GPIO controllers as well.

regards,
Santosh

[1] https://lkml.org/lkml/2013/8/27/509