Re: [Qemu-devel] [PATCH] pl110: Implement vertical compare/next base interrupts

[Peter Maydell <peter.maydell@linaro.org>]

On 23 January 2018 at 22:56, Linus Walleij <linus.walleij@linaro.org> wrote:
> This implements rudimentary support for interrupt generation on the
> PL110. I am working on a new DRI/KMS driver for Linux and since that
> uses the blanking interrupt, we need something to fire here. Without
> any interrupt support Linux waits for a while and then gives ugly
> messages about the vblank not working in the console (it does not
> hang perpetually or anything though, DRI is pretty forgiving).
>
> I solved it for now by setting up a timer to fire at 60Hz and pull
> the interrupts for "vertical compare" and "next memory base"
> at this interval. This works fine and fires roughly the same number
> of IRQs on QEMU as on the hardware and leaves the console clean
> and nice.
>
> People who want to create more accurate emulation can probably work
> on top of this if need be. It is certainly closer to the hardware
> behaviour than what we have today anyway.

Yeah, I think that "fire every 60Hz" is good enough for now.

Applied to target-arm.next (with the long lines checkpatch
complains about folded).

thanks
-- PMM