On Tue, May 14, 2013 at 5:01 PM, Ben Guthro <ben at guthro.net> wrote: > I am attempting to debug an issue with some Haswell laptop systems > which do not restore their screen after resuming from S3 when running > on the stable 3.8 kernel (3.8.13) > The backlight is OK, but the screen is just black. > > In trying to determine what was going wrong, I tried looking at the > output of intel_reg_dumper, in a good, and bad case: > > diff -u good_reg.txt bad_reg.txt > --- good_reg.txt 2013-05-14 15:08:44.361997000 +0000 > +++ bad_reg.txt 2013-05-14 15:09:20.480000000 +0000 > @@ -1,5 +1,4 @@ > - DCC: 0x00000000 (0x00000000f3400000 > 0x00000000f37fffff 0x00000000?? > -? ) > + DCC: 0x00000000 (0x00000000f3400000 > 0x00000000f37fffff 0x00000000??= ? ) > CHDECMISC: 0x00000000 (none, ch2 enh disabled, ch1 enh > disabled, ch0 enh disabled, flex disabled, ep not present) > C0DRB0: 0x00000000 (0x0000) > C0DRB1: 0x00000000 (0x0000) > @@ -63,17 +62,17 @@ > PIPEA_DP_LINK_N: 0x00000000 > CURSOR_A_BASE: 0x01061000 > CURSOR_A_CONTROL: 0x04000027 > - CURSOR_A_POSITION: 0x03a3032f > + CURSOR_A_POSITION: 0x01bb03fb > FPA0: 0x00000000 (n = 0, m1 = 0, m2 = 0) > FPA1: 0x00000000 (n = 0, m1 = 0, m2 = 0) > DPLL_A: 0x00000000 (disabled, non-dvo, VGA, default > clock, unknown mode, p1 = 0, p2 = 0) > DPLL_A_MD: 0x00000000 > - HTOTAL_A: 0x0821077f (1920 active, 2082 total) > - HBLANK_A: 0x0821077f (1920 start, 2082 end) > - HSYNC_A: 0x081307af (1968 start, 2068 end) > - VTOTAL_A: 0x045f0437 (1080 active, 1120 total) > - VBLANK_A: 0x045f0437 (1080 start, 1120 end) > - VSYNC_A: 0x044b0441 (1090 start, 1100 end) > + HTOTAL_A: 0x00000000 (1 active, 1 total) > + HBLANK_A: 0x00000000 (1 start, 1 end) > + HSYNC_A: 0x00000000 (1 start, 1 end) > + VTOTAL_A: 0x00000000 (1 active, 1 total) > + VBLANK_A: 0x00000000 (1 start, 1 end) > + VSYNC_A: 0x00000000 (1 start, 1 end) > BCLRPAT_A: 0x00000000 > VSYNCSHIFT_A: 0x00000000 > DSPBCNTR: 0x00004000 (disabled, pipe A) > > > It appears the registers that are saved, and restored in > i915_save_modeset_reg / i915_restore_modeset_reg is not working > properly. > > When I put some debug in, I discovered that it was bailing out of > i915_save_modeset_reg early since the DRIVER_MODESET bit was cleared. > However, it was set at the end of i915_init() > This, of course, confuses me. > > Am I seeing memory corruption here? It looks like I misread the code here, inversing an if statement state. That said, I don't really have any clues as to why the display is black after resuming from S3 Is this an eDP training issue? Are there any changesets I can try backporting? I tried this, but it didn't seem to help: https://patchwork.kernel.org/patch/2516601/
