Messages in this thread |  | | From | Ilia Mirkin <> | Date | Fri, 17 Nov 2017 14:52:45 -0500 | Subject | Re: Blank console but X11 works on MCP79 - old regression since 3.8 |
| |
On Fri, Nov 17, 2017 at 2:37 PM, Ilia Mirkin <imirkin@alum.mit.edu> wrote: > On Fri, Nov 17, 2017 at 2:25 PM, Ondrej Zary <linux@rainbow-software.org> wrote: >> On Friday 17 November 2017 18:41:17 Ilia Mirkin wrote: >>> On Fri, Nov 17, 2017 at 12:33 PM, Ondrej Zary >>> >>> <linux@rainbow-software.org> wrote: >>> > @@ -483,8 +483,8 @@ >>> > nouveau 0000:02:00.0: disp: 0860: 00000000 -> 00000500 >>> > nouveau 0000:02:00.0: disp: 0864: 00000000 >>> > nouveau 0000:02:00.0: disp: 0868: 00000000 -> 04000500 >>> > -nouveau 0000:02:00.0: disp: 086c: 00000000 -> 00100500 >>> > -nouveau 0000:02:00.0: disp: 0870: 0000e900 -> 00001e00 >>> > +nouveau 0000:02:00.0: disp: 086c: 00000000 -> 00100a00 >>> > +nouveau 0000:02:00.0: disp: 0870: 0000e900 -> 0000e800 >>> > nouveau 0000:02:00.0: disp: 0874: 00000000 -> ffff0000 >>> > nouveau 0000:02:00.0: disp: 0878: 00000000 >>> > nouveau 0000:02:00.0: disp: 0880: 05000000 >>> > >>> > Looks like it's using 8bpp (0x1e00) in 32MB case but 16bpp (0xe800) in >>> > 64MB case. Why? >>> > >>> > I get blank screen even with 64MB with video=1280x1024-8 kernel >>> > parameter. Console works with video=1280x1024-16 even with 32MB stolen >>> > memory. >>> > >>> > Conclusions: 8-bit support is broken and bpp reduction is weird. >>> >>> OK, well that makes a *ton* of sense (8bpp being broken). >>> >>> I think the idea of bpp reduction is that when you're on your shiny >>> new Riva TNT with 16MB of VRAM, you don't want to go crazy allocating >>> all that to a pinned fbcon - almost half of that would go to a single >>> 32bpp 1600x1200 buffer, more for 1920x1200. You want to be able to >>> have at least a few fb-sized buffers for backbuffer rendering, etc. >>> >>> The specific limits could probably use tweaking - I think they only >>> consider VRAM size, not the fb size. >>> >>> I guess 8bpp worked prior to the change you bisected though, so we >>> should figure out what we did wrong in the new code. >> >> Yes, booted 3.7 (last working kernel) and it's running in 8bpp. > > By the way, instead of booting $kernel, you can use modetest from > libdrm/tests. Not sure if it supports C8 though =/ > > I think the issue is this: > > - OUT_RING(evo, nv_crtc->lut.depth == 8 ? > - NV50_EVO_CRTC_CLUT_MODE_OFF : > - NV50_EVO_CRTC_CLUT_MODE_ON); > > Whereas now we always set 0xC0000000 (aka "ON").
In case I was being unclear, I'm talking about
https://github.com/skeggsb/nouveau/blob/master/drm/nouveau/nv50_display.c#L1808
and surrounding items. Looks like lut_clr sets 0x40000000 which was previously not used. Not sure what the difference between that and 0x00000000 is. This is what we have in rnndb for it:
https://github.com/envytools/envytools/blob/master/rnndb/display/nv_evo.xml#L408
So bit 30 is mode, set is "high res", unset is "low res". So really what we want is 0x80000000 which leaves the LUT enabled but uses the low-res mode?
All this could use some playing-around with.
-ilia
|  |