On Tue, May 21, 2013 at 4:00 AM, Daniel Vetter <daniel at ffwll.ch> wrote: > On Fri, May 17, 2013 at 09:26:18AM -0400, Ben Guthro wrote: >> On Fri, May 17, 2013 at 7:52 AM, Ben Guthro <ben at guthro.net> wrote: >> > On Thu, May 16, 2013 at 9:24 AM, Ben Guthro <ben at guthro.net> wrote: >> >> On Wed, May 15, 2013 at 4:42 PM, Ben Guthro <ben at guthro.net> wrote: >> >>> 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 >> > >> > It appears that S3 is not necessary. >> > >> > I can reproduce the black screen with just vbetool: >> > vbetool dpms off >> > vbetool dpms on >> > >> > Does this suggest a bios issue? >> >> This can be reliably reproduced on this machine, and worked around by >> saving the vbestate, and restoring it after the fact: >> >> (in a working state) >> vbetool vbestate save > vbe.save >> >> break the system: >> vbetool dpms off >> vbetool dpms on > > This will break kms since now you have the vbios and the linux kms driver > fighting over the same piece of hw. Does > > xset dpms force off > xset dpms force on > > cause similar issues? No, these work as expected (on 3.8) I didn't realize that these broke with KMS. I'll stick with the S3 reproduction. > > If not please make sure that vbetool isn't badly interfering with the > kernel modeset driver on suspend/resume. At least looking at your dmesg > and reg dumps vbe wreaking havoc with the kms driver seems like a rather > likely scenario. Also, can you please test latest 3.10-rc kernels? 3.10-rc2 doesn't seem to work at all - it boots to a black screen every time. Ben > > Cheers, Daniel > -- > Daniel Vetter > Software Engineer, Intel Corporation > +41 (0) 79 365 57 48 - http://blog.ffwll.ch
