[Intel-gfx] [PATCH] drm/i915: Redo WMs when cursor size changes

[Matt Roper]

On Fri, Feb 27, 2015 at 08:21:34AM -0800, Joe Konno wrote:
> On 02/27/2015 06:53 AM, Daniel Vetter wrote:
> > On Thu, Feb 26, 2015 at 05:47:35PM -0800, Matt Roper wrote:
> >> So your patch below could result in sleeps happening while vblanks are
> >> disabled, which is bad (IIRC, most of those sleeps are in the SKL
> >> codepath right now, but I think there's a workaround-related wait for
> >> IVB as well).
> >>
> >> Our watermark code needs a lot of work to beat it into proper shape for
> >> atomic and that's what I'm working on at the moment.
> > 
> > Alternative issue is that wm recompute happens before we update all the
> > legacy state. Tvrkto just stumbled over that for some of his skl watermark
> > code, he had to switch a few places in the wm code from looking at
> > plane->fb to look at plane->state->fb.
> > 
> > Similar changes might be needed for the cursor wm code -
> > cursor_width/height is kinda redundant since universal planes support.
> 
> Thanks for the insights, Matt and Dan. It's clear to me from Matt's analysis
> that my patch is a hack at best and nowhere near a proper fix.
> 
> This patch was submitted in the hopes of fixing a substantial graphical
> regression. Shall my patch be retooled as a "better" work-around, or will the
> regression stand until the watermark code is beat into proper shape?

I have a couple patches already written that I think might solve your
problem.  I'll extract those from my in-progress tree and post them
shortly for you to try.


Matt

-- 
Matt Roper
Graphics Software Engineer
IoTG Platform Enabling & Development
Intel Corporation
(916) 356-2795