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Re: [Qemu-devel] [PATCH 1/1] arm: virt: change GPIO trigger interrupt to
From: |
Wei Huang |
Subject: |
Re: [Qemu-devel] [PATCH 1/1] arm: virt: change GPIO trigger interrupt to pulse |
Date: |
Fri, 26 Feb 2016 09:28:41 -0600 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.5.0 |
On 02/26/2016 09:06 AM, Peter Maydell wrote:
> On 26 February 2016 at 14:54, Shannon Zhao <address@hidden> wrote:
>> On 2016/2/26 20:53, Peter Maydell wrote:
>>> I don't understand why a 500ms pulse is better than a short one.
>>>
>> Oh, I just pick a value which seems like a real latency for pressing a
>> button. What's your suggestion?
>
> I would prefer to avoid the pain of having a timer whose state
> needs to be migrated. It's unclear to me why a 500ms pulse
> will solve anything that an instantaneous pulse does not,
> so I'd like to better understand the problem first.
The problem we found with pulse was: only the last state change in GPIO
is received by guest VM. In other words, with 0(L)->1(H)->0(L) or
1(H)->0(L)->1(0), PL061 only sees the last state (0 and 1). I guess this
is because QEMU is non-preemptive. The solution is to have the following
steps:
* qemu_set_irq(gpio_in, 1)
* yeild to guest VM
* qemu_set_irq(gpio_in, 0)
Is there any way to do so in QEMU without using timer?
>
> thanks
> -- PMM
>
- Re: [Qemu-devel] [PATCH 1/1] arm: virt: change GPIO trigger interrupt to pulse, (continued)
- Re: [Qemu-devel] [PATCH 1/1] arm: virt: change GPIO trigger interrupt to pulse, Shannon Zhao, 2016/02/03
- Re: [Qemu-devel] [PATCH 1/1] arm: virt: change GPIO trigger interrupt to pulse, Wei Huang, 2016/02/04
- Re: [Qemu-devel] [PATCH 1/1] arm: virt: change GPIO trigger interrupt to pulse, Shannon Zhao, 2016/02/04
- Re: [Qemu-devel] [PATCH 1/1] arm: virt: change GPIO trigger interrupt to pulse, Wei Huang, 2016/02/09
- Re: [Qemu-devel] [PATCH 1/1] arm: virt: change GPIO trigger interrupt to pulse, Shannon Zhao, 2016/02/20
- Re: [Qemu-devel] [PATCH 1/1] arm: virt: change GPIO trigger interrupt to pulse, Wei Huang, 2016/02/24
- Re: [Qemu-devel] [PATCH 1/1] arm: virt: change GPIO trigger interrupt to pulse, Shannon Zhao, 2016/02/26
- Re: [Qemu-devel] [PATCH 1/1] arm: virt: change GPIO trigger interrupt to pulse, Peter Maydell, 2016/02/26
- Re: [Qemu-devel] [PATCH 1/1] arm: virt: change GPIO trigger interrupt to pulse, Shannon Zhao, 2016/02/26
- Re: [Qemu-devel] [PATCH 1/1] arm: virt: change GPIO trigger interrupt to pulse, Peter Maydell, 2016/02/26
- Re: [Qemu-devel] [PATCH 1/1] arm: virt: change GPIO trigger interrupt to pulse,
Wei Huang <=
- Re: [Qemu-devel] [PATCH 1/1] arm: virt: change GPIO trigger interrupt to pulse, Peter Maydell, 2016/02/26
- Re: [Qemu-devel] [PATCH 1/1] arm: virt: change GPIO trigger interrupt to pulse, Shannon Zhao, 2016/02/26