Getting said error both on my HSW 4200U and 4770. No apparent consequences or related dmesg lines. Driver module is compiled-in. [drm:drm_calc_timestamping_constants] *ERROR* crtc 21: Can't calculate constants, dotclock = 0! Kernel is drm-nightly-intel started with i915_enable_rc6=7. On 4770: [ 0.796626] [drm] Initialized drm 1.1.0 20060810 [ 0.796908] [drm] Memory usable by graphics device = 2048M [ 0.796909] [drm] VT-d active for gfx access [ 0.796910] checking generic (d0000000 300000) vs hw (d0000000 10000000) [ 0.796910] fb: switching to inteldrmfb from EFI VGA [ 0.796918] Console: switching to colour dummy device 80x25 [ 0.796955] [drm] Replacing VGA console driver [ 0.801751] [drm] Supports vblank timestamp caching Rev 2 (21.10.2013). [ 0.801752] [drm] Driver supports precise vblank timestamp query. [ 0.801761] [drm] DMAR active, disabling use of stolen memory [ 0.801803] vgaarb: device changed decodes: PCI:0000:00:02.0,olddecodes=io+mem,decodes=none:owns=io+mem [ 0.868011] [drm:drm_calc_timestamping_constants] *ERROR* crtc 21: Can't calculate constants, dotclock = 0! [ 0.873265] ACPI: Video Device [GFX0] (multi-head: yes rom: no post: no) [ 0.873534] acpi device:60: registered as cooling_device13 [ 0.873571] input: Video Bus as /devices/LNXSYSTM:00/LNXSYBUS:00/PNP0A08:00/LNXVIDEO:00/input/input2 [ 0.873582] [drm] Initialized i915 1.6.0 20150717 for 0000:00:02.0 on minor 0
Please retry current nightly. i915_enable_rc6=7 doesn't do you any good, please just remove it.
Still occurs at drm-intel-nightly: 2015y-08m-19d-08h-17m-47s Log is now: 0.796590] [drm] Initialized drm 1.1.0 20060810 [ 0.796600] ------------[ cut here ]------------ [ 0.796603] WARNING: CPU: 0 PID: 1 at drivers/gpu/drm/drm_drv.c:570 drm_dev_alloc+0x254/0x320() [ 0.796603] Modules linked in: [ 0.796605] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.2.0-1-cu #1 [ 0.796606] Hardware name: Gigabyte Technology Co., Ltd. G1.Sniper M5/G1.Sniper M5, BIOS T01 02/03/2015 [ 0.796607] 0000000000000000 000000004240aefe ffff88041d28bbb8 ffffffff81941f98 [ 0.796608] 0000000000000000 0000000000000000 ffff88041d28bbf8 ffffffff810e5386 [ 0.796609] ffff88041d28bc08 ffff88041c0d6000 ffffffff81eb1540 ffff88041c6dc098 [ 0.796611] Call Trace: [ 0.796613] [<ffffffff81941f98>] dump_stack+0x4c/0x6e [ 0.796615] [<ffffffff810e5386>] warn_slowpath_common+0x86/0xc0 [ 0.796617] [<ffffffff810e54ba>] warn_slowpath_null+0x1a/0x20 [ 0.796618] [<ffffffff815a16b4>] drm_dev_alloc+0x254/0x320 [ 0.796620] [<ffffffff815a369b>] drm_get_pci_dev+0x3b/0x1e0 [ 0.796622] [<ffffffff815bc224>] i915_pci_probe+0x34/0x50 [ 0.796624] [<ffffffff814b7799>] pci_device_probe+0x89/0xe0 [ 0.796627] [<ffffffff8167cfd4>] driver_probe_device+0x1f4/0x460 [ 0.796628] [<ffffffff8167d2d0>] __driver_attach+0x90/0xa0 [ 0.796629] [<ffffffff8167d240>] ? driver_probe_device+0x460/0x460 [ 0.796630] [<ffffffff8167abfc>] bus_for_each_dev+0x6c/0xc0 [ 0.796631] [<ffffffff8167c7ce>] driver_attach+0x1e/0x20 [ 0.796633] [<ffffffff8167c32b>] bus_add_driver+0x1eb/0x280 [ 0.796634] [<ffffffff8167dbe0>] driver_register+0x60/0xe0 [ 0.796635] [<ffffffff814b6ec9>] __pci_register_driver+0x49/0x50 [ 0.796637] [<ffffffff815a391b>] drm_pci_init+0xdb/0x100 [ 0.796638] [<ffffffff81f976cf>] ? mipi_dsi_bus_init+0x12/0x12 [ 0.796639] [<ffffffff81f97774>] i915_init+0xa5/0xad [ 0.796640] [<ffffffff81002123>] do_one_initcall+0xb3/0x200 [ 0.796642] [<ffffffff81101f71>] ? parse_args+0x271/0x4a0 [ 0.796644] [<ffffffff81f4c1b3>] kernel_init_freeable+0x179/0x218 [ 0.796645] [<ffffffff819372b0>] ? rest_init+0x90/0x90 [ 0.796646] [<ffffffff819372be>] kernel_init+0xe/0xe0 [ 0.796648] [<ffffffff81948d5f>] ret_from_fork+0x3f/0x70 [ 0.796649] [<ffffffff819372b0>] ? rest_init+0x90/0x90 [ 0.796651] ---[ end trace 38f2660276b3a315 ]--- [ 0.796925] [drm] Memory usable by graphics device = 2048M [ 0.796926] [drm] VT-d active for gfx access [ 0.796927] checking generic (d0000000 300000) vs hw (d0000000 10000000) [ 0.796928] fb: switching to inteldrmfb from EFI VGA [ 0.796937] Console: switching to colour dummy device 80x25 [ 0.796973] [drm] Replacing VGA console driver [ 0.803366] [drm] Supports vblank timestamp caching Rev 2 (21.10.2013). [ 0.803367] [drm] Driver supports precise vblank timestamp query. [ 0.803372] [drm:intel_parse_bios] *ERROR* General definiton block child device size is too small. [ 0.803379] [drm] DMAR active, disabling use of stolen memory [ 0.803420] vgaarb: device changed decodes: PCI:0000:00:02.0,olddecodes=io+mem,decodes=none:owns=io+mem [ 0.871079] [drm:drm_calc_timestamping_constants] *ERROR* crtc 21: Can't calculate constants, dotclock = 0! [ 0.876358] ACPI: Video Device [GFX0] (multi-head: yes rom: no post: no) [ 0.876634] acpi device:60: registered as cooling_device13 [ 0.876671] input: Video Bus as /devices/LNXSYSTM:00/LNXSYBUS:00/PNP0A08:00/LNXVIDEO:00/input/input2 [ 0.876682] [drm] Initialized i915 1.6.0 20150731 for 0000:00:02.0 on minor 0 Removed i915_enable_rc6, thanks for the hint.
http://lists.freedesktop.org/archives/intel-gfx/2015-August/073673.html
Fixes this issue; the new warning & other error remain.
(In reply to Andreas Reis from comment #4) > Fixes this issue; the new warning & other error remain. Did you try both patches, i.e. http://patchwork.freedesktop.org/patch/57095 http://patchwork.freedesktop.org/patch/57096
Both.
I sent out a patch for this some time ago which Maarten also fixed up. Basically the encoders need to be read out before the planes. And after that stage we copy over the dotclock which will make this error go away. http://lists.freedesktop.org/archives/intel-gfx/2015-August/073028.html
2/2 and 3/2 of Ville Syrjälä's patches were committed, but not 1/3. Without that one I still get the error.
This should be fixed by commit 7f4c62840cc416986f983a8c68f7010c97e06daf Author: Ville Syrjälä <ville.syrjala@linux.intel.com> Date: Thu Sep 10 18:59:07 2015 +0300 drm/i915: Assign hwmode after encoder state readout and commit 0f64614dde172e4f4b2734a55091a4d307863cbb Author: Ville Syrjälä <ville.syrjala@linux.intel.com> Date: Wed Aug 26 19:39:18 2015 +0300 drm/i915: Fix clock readout when pipes are enabled w/o ports in current drm-intel-nightly branch of http://cgit.freedesktop.org/drm-intel. Please reopen if the problem still persists with that.
*** Bug 92451 has been marked as a duplicate of this bug. ***
Closing resolved+fixed after one year without comments.
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