On Mon, Sep 10, 2018 at 08:53:15PM +0200, Mark Kettenis wrote:
> When we're cold, vblank interrupts don't happen, so we would wait
> forever. I added a short-circuit for this case, but apparently some
> output connector detection code in inteldrm(4) relies on a delay here
> to reliably detect whether something is connected or not.
>
> I tried fixing this in our Linux compat code, but I didn't come up
> with a working solution. So this adds an #ifdef __OpenBSD__ block in
> the drm_wait_one_vblank() implementations that we hopefully won't miss
> when updating the drm code in the future.
>
> Thanks to Philippe Meunier for figuring out the root cause of the
> problem. And sorry for the delay...
>
> ok?
Mostly for reporting "it works". So I am fine with it. :)
I tested it on two differents laptops with inteldrm(4) and screen
problems:
- on i386 (Intel 82945GM Video)
console switchs from "848x480, 32bpp" to "1280x800, 32bpp"
- on amd64 (Intel 82945GM Video too)
console switchs from "848x480, 32bpp" to "1024x768, 32bpp" (with
external VGA attached)
and now I am able to boot with a second screen attached to VGA
without problem. before when connected during boot, the output
was only on VGA and LVDS was black.
Thanks.
--
Sebastien Marie
> Index: dev/pci/drm/drm_irq.c
> ===================================================================
> RCS file: /cvs/src/sys/dev/pci/drm/drm_irq.c,v
> retrieving revision 1.70
> diff -u -p -r1.70 drm_irq.c
> --- dev/pci/drm/drm_irq.c 28 Mar 2018 05:27:28 -0000 1.70
> +++ dev/pci/drm/drm_irq.c 10 Sep 2018 18:45:33 -0000
> @@ -1317,8 +1317,21 @@ void drm_wait_one_vblank(struct drm_devi
> int ret;
> u32 last;
>
> - if (WARN_ON(pipe >= dev->num_crtcs) || cold)
> + if (WARN_ON(pipe >= dev->num_crtcs))
> return;
> +
> +#ifdef __OpenBSD__
> + /*
> + * If we're cold, vblank interrupts won't happen even if
> + * they're turned on by the driver. Just stall long enough
> + * for a vblank to pass. This assumes a vrefresh of at least
> + * 25 Hz.
> + */
> + if (cold) {
> + delay(40000);
> + return;
> + }
> +#endif
>
> ret = drm_vblank_get(dev, pipe);
> if (WARN(ret, "vblank not available on crtc %i, ret=%i\n", pipe, ret))
>
