[PATCH xserver v2 22/22] xwayland: Guard against very late vblanks

[Roman Gilg]

On Wed, Feb 28, 2018 at 6:43 PM, Michel Dänzer <michel at daenzer.net> wrote:
> I'm unable to reproduce the issue you described with Steam (without this
> patch series applied). I'd really like to know where the bogus target
> MSC values you're seeing are coming from. What are the values of the
> window_msc parameter and window_priv->msc_offset in
> present_window_to_crtc_msc?

You don't have to go that far. I did read out on current master high
target msc values directly for stuff->target_msc in
proc_present_pixmap. But this happened only on like two or three
occasions directly at the startup of the Steam client while hundreds
of other present_pixmap requests before and after had normal
stuff->target_msc values.

So just put a line

ErrorF("XXX %lu\n", stuff->target_msc);

in proc_present_pixmap and if you look carefully through the debug
output there should be one or two very high numbers in comparison to
all the other values.