Message-ID: <CAKMK7uF=peNM1Ua16OhwivAfmaN+PdFLPWWSJv4jyzsnOp0XNA@mail.gmail.com>
Date:   Fri, 21 Jul 2017 00:05:50 +0200
From:   Daniel Vetter <daniel.vetter@...ll.ch>
To:     Tobias Klausmann <tobias.johannes.klausmann@....thm.de>
Cc:     Ilia Mirkin <imirkin@...m.mit.edu>,
        "nouveau@...ts.freedesktop.org" <nouveau@...ts.freedesktop.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>
Subject: Re: [Nouveau] [PATCH] drm: disable vblank only if it got previously enabled

On Thu, Jul 20, 2017 at 11:58 PM, Tobias Klausmann
<tobias.johannes.klausmann@....thm.de> wrote:
> Mh ok,
>
> paper over in nouveau_display_fini until Ben comes up with a better idea
> then?!

No paper needed, just don't call drm_vblank_off for the atomic case.
Not sure why that patch isn't landed yet, it should be simple.
-Daniel

>
> Greetings,
>
> Tobias
>
>
> On 7/20/17 10:13 AM, Daniel Vetter wrote:
>> On Wed, Jul 19, 2017 at 04:10:50PM -0400, Ilia Mirkin wrote:
>>> I believe the solution is to not call drm_crtc_vblank_off for atomic
>>> modesetting in nouveau_display_fini. I think Ben's working on it.
>> Yes, the goal of vblank_on/off was very much to not paper over driver bugs
>> with clever tricks like these. If the driver cant keep track of its
>> vblank, something has gone wrong, and the core should _not_ fix it up.
>> Otherwise we're back to the old style vblank horror show.
>>
>> Thanks, Daniel
>>
>>> On Wed, Jul 19, 2017 at 1:25 PM, Tobias Klausmann
>>> <tobias.johannes.klausmann@....thm.de> wrote:
>>>> mimic the behavior of vblank_disable_fn(), another caller of
>>>> drm_vblank_disable_and_save().
>>>>
>>>> This avoids oopsing, while trying to disable vblank on a not connected display:
>>>>
>>>> [   12.768079] WARNING: CPU: 0 PID: 274 at drivers/gpu/drm/drm_vblank.c:609 drm_calc_vbltimestamp_from_scanoutpos+0x296/0x320 [drm]
>>>> [   12.768080] Modules linked in: bnep snd_hda_codec_hdmi rtsx_usb_sdmmc uvcvideo rtsx_usb_ms mmc_core videobuf2_vmalloc memstick videobuf2_memops videobuf2_v4l2 videobuf2_core rtsx_usb videodev btusb btrtl arc4 snd_hda_codec_realtek snd_hda_codec_generic joydev nls_iso8859_1 hid_multitouch nls_cp437 intel_rapl x86_pkg_temp_thermal intel_powerclamp vfat coretemp fat kvm_intel iTCO_wdt iTCO_vendor_support kvm irqbypass crct10dif_pclmul crc32_pclmul crc32c_intel ghash_clmulni_intel pcbc aesni_intel ath10k_pci snd_hda_intel ath10k_core aes_x86_64 snd_hda_codec crypto_simd ath glue_helper cryptd snd_hda_core mac80211 snd_hwdep snd_pcm pcspkr r8169 cfg80211 mii snd_timer acer_wmi snd sparse_keymap wmi_bmof idma64 hci_uart virt_dma mei_me soundcore i2c_i801 mei btbcm shpchp intel_lpss_pci intel_pch_thermal
>>>> [   12.768130]  serdev btqca ucsi_acpi btintel typec_ucsi thermal typec bluetooth ecdh_generic battery ac pinctrl_sunrisepoint rfkill intel_lpss_acpi pinctrl_intel intel_lpss acpi_pad nouveau serio_raw i915 mxm_wmi ttm i2c_algo_bit drm_kms_helper xhci_pci syscopyarea sysfillrect sysimgblt xhci_hcd fb_sys_fops usbcore drm i2c_hid wmi video button sg efivarfs
>>>> [   12.768158] CPU: 0 PID: 274 Comm: kworker/0:2 Not tainted 4.12.0-desktop-debug-drm+ #2
>>>> [   12.768160] Hardware name: Acer Aspire VN7-593G/Pluto_KLS, BIOS V1.04 03/30/2017
>>>> [   12.768164] Workqueue: pm pm_runtime_work
>>>> [   12.768166] task: ffff889bf1627040 task.stack: ffff9541013e4000
>>>> [   12.768180] RIP: 0010:drm_calc_vbltimestamp_from_scanoutpos+0x296/0x320 [drm]
>>>> [   12.768181] RSP: 0018:ffff9541013e7b30 EFLAGS: 00010086
>>>> [   12.768183] RAX: 000000000000001c RBX: ffff889b4cebd000 RCX: 0000000000000004
>>>> [   12.768184] RDX: 0000000080000004 RSI: ffffffff87a2d952 RDI: 00000000ffffffff
>>>> [   12.768186] RBP: ffff9541013e7b90 R08: 0000000000000001 R09: 000000000000039f
>>>> [   12.768187] R10: ffffffffc05fe530 R11: 0000000000000000 R12: 0000000000000000
>>>> [   12.768188] R13: ffff9541013e7ba4 R14: ffff889bf0426088 R15: ffff889bf0426000
>>>> [   12.768190] FS:  0000000000000000(0000) GS:ffff889bfec00000(0000) knlGS:0000000000000000
>>>> [   12.768191] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>>>> [   12.768192] CR2: 000000edb16580b8 CR3: 000000020cc09000 CR4: 00000000003406f0
>>>> [   12.768193] Call Trace:
>>>> [   12.768198]  ? enqueue_task_fair+0x64/0x600
>>>> [   12.768211]  ? drm_get_last_vbltimestamp+0x47/0x70 [drm]
>>>> [   12.768223]  ? drm_update_vblank_count+0x65/0x240 [drm]
>>>> [   12.768227]  ? pci_pm_runtime_resume+0xa0/0xa0
>>>> [   12.768238]  ? drm_vblank_disable_and_save+0x55/0xc0 [drm]
>>>> [   12.768250]  ? drm_crtc_vblank_off+0xa9/0x1e0 [drm]
>>>> [   12.768253]  ? pci_pm_runtime_resume+0xa0/0xa0
>>>> [   12.768299]  ? nouveau_display_fini+0x56/0xd0 [nouveau]
>>>> [   12.768339]  ? nouveau_display_suspend+0x51/0x110 [nouveau]
>>>> [   12.768378]  ? nouveau_do_suspend+0x76/0x1c0 [nouveau]
>>>> [   12.768413]  ? nouveau_pmops_runtime_suspend+0x54/0xb0 [nouveau]
>>>> [   12.768416]  ? pci_pm_runtime_suspend+0x5c/0x160
>>>> [   12.768419]  ? __rpm_callback+0xb6/0x1e0
>>>> [   12.768423]  ? kobject_uevent_env+0x111/0x5e0
>>>> [   12.768425]  ? pci_pm_runtime_resume+0xa0/0xa0
>>>> [   12.768427]  ? rpm_callback+0x1f/0x70
>>>> [   12.768429]  ? pci_pm_runtime_resume+0xa0/0xa0
>>>> [   12.768431]  ? rpm_suspend+0x11f/0x640
>>>> [   12.768441]  ? drm_fb_helper_hotplug_event+0x9a/0xe0 [drm_kms_helper]
>>>> [   12.768447]  ? output_poll_execute+0x17b/0x1a0 [drm_kms_helper]
>>>> [   12.768449]  ? pm_runtime_work+0x64/0xa0
>>>> [   12.768453]  ? process_one_work+0x1db/0x410
>>>> [   12.768456]  ? worker_thread+0x47/0x3d0
>>>> [   12.768459]  ? process_one_work+0x410/0x410
>>>> [   12.768461]  ? kthread+0x117/0x130
>>>> [   12.768463]  ? kthread_create_on_node+0x40/0x40
>>>> [   12.768466]  ? ret_from_fork+0x25/0x30
>>>> [   12.768468] Code: 80 3d 26 f3 01 00 00 0f 85 ad fd ff ff 48 8b 43 20 48 c7 c7 31 a2 20 c0 c6 05 0e f3 01 00 01 48 8b b0 60 01 00 00 e8 75 2e ec c6 <0f> ff e9 88 fd ff ff 31 f6 44 88 55 b0 e8 38 fa ed c6 44 0f b6
>>>> [   12.768508] ---[ end trace d9bb853af3659bd5 ]---
>>>>
>>>> Signed-off-by: Tobias Klausmann <tobias.johannes.klausmann@....thm.de>
>>>> ---
>>>>  drivers/gpu/drm/drm_vblank.c | 5 ++++-
>>>>  1 file changed, 4 insertions(+), 1 deletion(-)
>>>>
>>>> diff --git a/drivers/gpu/drm/drm_vblank.c b/drivers/gpu/drm/drm_vblank.c
>>>> index a233a6be934a..4a21756bf2bd 100644
>>>> --- a/drivers/gpu/drm/drm_vblank.c
>>>> +++ b/drivers/gpu/drm/drm_vblank.c
>>>> @@ -1140,8 +1140,11 @@ void drm_crtc_vblank_off(struct drm_crtc *crtc)
>>>>
>>>>         /* Avoid redundant vblank disables without previous
>>>>          * drm_crtc_vblank_on(). */
>>>> -       if (drm_core_check_feature(dev, DRIVER_ATOMIC) || !vblank->inmodeset)
>>>> +       if (drm_core_check_feature(dev, DRIVER_ATOMIC) || (!vblank->inmodeset &&
>>>> +               vblank->enabled)) {
>>>> +               DRM_DEBUG("disabling vblank on crtc %u\n", pipe);
>>>>                 drm_vblank_disable_and_save(dev, pipe);
>>>> +       }
>>>>
>>>>         wake_up(&vblank->queue);
>>>>
>>>> --
>>>> 2.13.2
>>>>
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch

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