Re: [Qemu-devel] [PATCH 1/1] arm: virt: change GPIO trigger interrupt to pulse

[Shannon Zhao <zhaoshenglong@huawei.com>]

On 2016/2/4 0:01, Wei Huang wrote:
> 
> On 2/3/16 04:46, Peter Maydell wrote:
>> > On 3 February 2016 at 07:15, Michael Tokarev <mjt@tls.msk.ru> wrote:
>>> >> 28.01.2016 21:22, Wei Huang wrote:
>>>> >>> When QEMU is hook'ed up with libvirt/virsh, the first ACPI reboot
>>>> >>> request will succeed; but the following shutdown/reboot requests
>>>> >>> fail to trigger VMs to react. Notice that in mach-virt machine
>>>> >>> model GPIO is defined as edge-triggered and active-high in ACPI.
>>>> >>> This patch changes the behavior of powerdown notifier from PULLUP
>>>> >>> to PULSE. It solves the problem described above (i.e. reboot
>>>> >>> continues to work).
>>> >>
>>> >> So, what's the outcome of this? :)
>> > 
>> > This patch is definitely wrong. The patch to fix up the
>> > gpio reset stuff is definitely the right idea. Whether it
>> > fixes the reported failure or some further change is also
>> > needed is currently unclear.
> I will NAK this one for now. Please see V2 patch, which is necessary. In
> the meanwhile, I think there is a problem with pulling-up only in
> current implementation. Let me debug Shannon's DT problem first.
> 
Hi Wei,

The reason of DT problem is that when we use qemu_irq_pulse(i.e
qemu_set_irq(qdev_get_gpio_in(pl061_dev, 3), 1);
qemu_set_irq(qdev_get_gpio_in(pl061_dev, 3), 0);), it will inject the
GPIO interrupt until it executes
qemu_set_irq(qdev_get_gpio_in(pl061_dev, 3), 0) because the qemu main
thread is serialized and then guest will get the button value as zero,
so it's failed to report the input event.

See gpio_keys_gpio_report_event
 in drivers/input/keyboard/gpio_keys.c
int state = gpio_get_value_cansleep(button->gpio);

The state is always zero.

The solution I think would be making the each
qemu_set_irq(qdev_get_gpio_in(pl061_dev, 3), 1 or 0) cloud inject an
interrupt to guest.

Thanks,
-- 
Shannon