Re: [Intel-gfx] 4.17-rc2: Could not determine valid watermarks for inherited state

From: Ville Syrjälä
Date: Thu Apr 26 2018 - 11:16:52 EST

On Thu, Apr 26, 2018 at 05:56:14PM +0300, Ville Syrjälä wrote:
> On Thu, Apr 26, 2018 at 10:27:19AM -0400, Dave Jones wrote:
> > [ 1.176131] [drm:i9xx_get_initial_plane_config] pipe A/primary A with fb: size=800x600@32, offset=0, pitch 3200, size 0x1d4c00
> > [ 1.176161] [drm:i915_gem_object_create_stolen_for_preallocated] creating preallocated stolen object: stolen_offset=0x0000000000000000, gtt_offset=0x0000000000000000, size=0x00000000001d5000
> > [ 1.176312] [drm:intel_alloc_initial_plane_obj.isra.127] initial plane fb obj (ptrval)
> > [ 1.176351] [drm:intel_modeset_init] pipe A active planes 0x1
> > [ 1.176456] [drm:drm_atomic_helper_check_plane_state] Plane must cover entire CRTC
> > [ 1.176481] [drm:drm_rect_debug_print] dst: 800x600+0+0
> > [ 1.176494] [drm:drm_rect_debug_print] clip: 1366x768+0+0
> OK, so that's the problem right there. The fb we took over from the
> BIOS was 800x600, but now we're trying to set up a 1366x768 mode.
> We seem to be missing checks to make sure the initial fb is actually
> big enough for the mode we're currently using :(

Actually we do read out the pipe src size as 800x600 initially, which
make sense. And we even stuff that into the mode.h/vdisplay, so up to
that point everything is pretty much correct. It goes wrong is when
intel_modeset_readout_hw_state() calls intel_mode_from_pipe_config()
as that will override the h/vdisplay with the actual crtc timings
instead of the pipe src size.

So I suppose we should be able to just add the sanity checks for the
fb vs. h/vdisplay, and at least we should get past this error. A
slightly bigger mystery is what will happen later when our pipe src
size doesn't actually agree with the h/vdisplay. The first modeset
will correct it, but we might want some kind of extra sanitize step
for fastboot type of stuff.

Ville Syrjälä