vc4 unbalanced irq fix

[mirzak]

Fixes the following warning:

[  414.810574] WARNING: CPU: 1 PID: 394 at /kernel-source//kernel/irq/manage.c:527 __enable_irq+0x54/0x80
[  414.820018] Unbalanced enable for IRQ 40
[  414.823993] Modules linked in: rfcomm bnep hci_uart btbcm ecryptfs bluetooth panel_raspberrypi_touchscreen brcmfmac brcmutil cfg80211 rfkill vc4 snd_soc_core snd_compress i2c_gpio snd_pcm_dmaengine bcm2835_gpi
omem uio_pdrv_genirq uio fixed evdev joydev sch_fq_codel snd_bcm2835 snd_pcm snd_timer snd hid_multitouch fuse ipv6
[  414.853179] CPU: 1 PID: 394 Comm: QSGRenderThread Tainted: G        W       4.9.80 #1
[  414.861123] Hardware name: BCM2835
[  414.864592] [<8011102c>] (unwind_backtrace) from [<8010c8f0>] (show_stack+0x20/0x24)
[  414.872458] [<8010c8f0>] (show_stack) from [<8045af48>] (dump_stack+0xcc/0x110)
[  414.879886] [<8045af48>] (dump_stack) from [<8011e7fc>] (__warn+0xf8/0x110)
[  414.886956] [<8011e7fc>] (__warn) from [<8011e85c>] (warn_slowpath_fmt+0x48/0x50)
[  414.894556] [<8011e85c>] (warn_slowpath_fmt) from [<8017752c>] (__enable_irq+0x54/0x80)
[  414.902685] [<8017752c>] (__enable_irq) from [<8017759c>] (enable_irq+0x44/0x7c)
[  414.910283] [<8017759c>] (enable_irq) from [<7f1c2b64>] (vc4_irq_postinstall+0x24/0x40 [vc4])
[  414.919062] [<7f1c2b64>] (vc4_irq_postinstall [vc4]) from [<7f1c5858>] (vc4_v3d_runtime_resume+0x58/0x60 [vc4])
[  414.929368] [<7f1c5858>] (vc4_v3d_runtime_resume [vc4]) from [<8053eb74>] (pm_generic_runtime_resume+0x3c/0x48)
[  414.939617] [<8053eb74>] (pm_generic_runtime_resume) from [<80542a28>] (__genpd_runtime_resume+0x3c/0xc0)
[  414.949334] [<80542a28>] (__genpd_runtime_resume) from [<80544638>] (genpd_runtime_resume+0x84/0x198)
[  414.958699] [<80544638>] (genpd_runtime_resume) from [<80540140>] (__rpm_callback+0x48/0x98)
[  414.967271] [<80540140>] (__rpm_callback) from [<805401c0>] (rpm_callback+0x30/0x90)
[  414.975138] [<805401c0>] (rpm_callback) from [<805415ec>] (rpm_resume+0x500/0x7c0)
[  414.982827] [<805415ec>] (rpm_resume) from [<8054191c>] (__pm_runtime_resume+0x70/0x9c)
[  414.991025] [<8054191c>] (__pm_runtime_resume) from [<7f1bf6c4>] (vc4_submit_cl_ioctl+0x2e4/0x9cc [vc4])
[  415.000716] [<7f1bf6c4>] (vc4_submit_cl_ioctl [vc4]) from [<80511dfc>] (drm_ioctl+0x1f0/0x3f8)
[  415.009466] [<80511dfc>] (drm_ioctl) from [<802867a4>] (do_vfs_ioctl+0xb0/0x814)
[  415.016981] [<802867a4>] (do_vfs_ioctl) from [<80286f4c>] (SyS_ioctl+0x44/0x68)
[  415.024410] [<80286f4c>] (SyS_ioctl) from [<801082a0>] (ret_fast_syscall+0x0/0x1c)
[  415.032092] ---[ end trace 3f3b9a47efa1f1f8 ]---

[pelwell]

It looks like a pair of commits have been cherry-picked to 4.9:

253696ccd613 ("drm/vc4: Account for interrupts in flight")
ce9caf2f79a5 ("drm/vc4: Move IRQ enable to PM path")

The second commit is a partial reversion and modification of the second.
Then the first commit was cherry-picked again, and this is a re-cherry-pick of the second.

@stschake Does this fix look right to you?

[stschake]

I guess this is a result from patches trickling down from the stable kernel that the RPi one already got through some other pathway, causing conflicts and wrong resolutions. Been there :)

That said, yeah, the enable_irq in postinstall should not be there, so this is correct. The rpi 4.9 branch currently has the one in vc4_v3d_runtime_resume (where it is correct) and also the one in postinstall, which causes the unbalance warning since we then enable the IRQ twice when coming back from PM suspend (and the VC4 DRM driver is pretty eager to suspend itself, so this happens often).

[pelwell]

Thanks.