Re: [PATCH v2] usb: dwc2: call dwc2_is_controller_alive() under spinlock

Felipe Balbi
2015-01-14T19:38:47Z

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On Wed, Jan 14, 2015 at 07:45:31AM +0100, Robert Baldyga wrote:
> This patch fixes bug described here:
> https://lkml.org/lkml/2014/12/22/185
>
> Signed-off-by: Robert Baldyga <r.baldyga@samsung.com>
> ---
>
> Changelog:
>
> v2:
> - fixed comment from Paul Zimmerman
>
> v1: https://lkml.org/lkml/2015/1/13/186
>
> drivers/usb/dwc2/core_intr.c | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/usb/dwc2/core_intr.c b/drivers/usb/dwc2/core_intr.c
> index ad43c5b..02e3e2d 100644
> --- a/drivers/usb/dwc2/core_intr.c
> +++ b/drivers/usb/dwc2/core_intr.c
> @@ -476,13 +476,13 @@ irqreturn_t dwc2_handle_common_intr(int irq, void *dev)
> u32 gintsts;
> irqreturn_t retval = IRQ_NONE;
>
> + spin_lock(&hsotg->lock);
> +
> if (!dwc2_is_controller_alive(hsotg)) {

This is really, really odd. Register accesses are atomic, so the lock
isn't really doing anything. Besides, you're calling
dwc2_is_controller_alive() from within the IRQ handler, so IRQs are
already disabled.

When the problem happens, do you see this "Controller is dead" message ?

--
balbi

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