Re: [PATCH] OMAPDSS: Check if RPM enabled before trying to change state

[Tomi Valkeinen <tomi.valkeinen@ti.com>]

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On Tue, 2012-06-26 at 14:02 +0530, Jassi Brar wrote:

> Something non-omapdss in vanilla breaks suspend/resume.

I was able to reproduce (probably) the same issue with omap3 overo. Does
this looks familiar:

[ 2267.140197] ------------[ cut here ]------------
[ 2267.145172] WARNING: at drivers/video/omap2/dss/dispc.c:377 dispc_runtime_get+0x60/0x7c [omapdss]
()
[ 2267.154846] Modules linked in: omapfb panel_generic_dpi omapdss cfbimgblt cfbfillrect cfbcopyarea
 [last unloaded: omapdss]
[ 2267.166595] [<c001b61c>] (unwind_backtrace+0x0/0xf0) from [<c0040238>] (warn_slowpath_common+0x4c
/0x64)
[ 2267.176605] [<c0040238>] (warn_slowpath_common+0x4c/0x64) from [<c004026c>] (warn_slowpath_null+0
x1c/0x24)
[ 2267.186859] [<c004026c>] (warn_slowpath_null+0x1c/0x24) from [<bf0d7918>] (dispc_runtime_get+0x60
/0x7c [omapdss])
[ 2267.197814] [<bf0d7918>] (dispc_runtime_get+0x60/0x7c [omapdss]) from [<bf0e3148>] (omapdss_dpi_d
isplay_enable+0x48/0x230 [omapdss])
[ 2267.210479] [<bf0e3148>] (omapdss_dpi_display_enable+0x48/0x230 [omapdss]) from [<bf110034>] (gen
eric_dpi_panel_check_timings+0x30/0x7c [panel_generic_dpi])
[ 2267.225311] [<bf110034>] (generic_dpi_panel_check_timings+0x30/0x7c [panel_generic_dpi]) from [<b
f11008c>] (generic_dpi_panel_resume+0xc/0x1c [panel_generic_dpi])
[ 2267.240722] [<bf11008c>] (generic_dpi_panel_resume+0xc/0x1c [panel_generic_dpi]) from [<bf0de654>
] (dss_resume_device+0x28/0x40 [omapdss])
[ 2267.253936] [<bf0de654>] (dss_resume_device+0x28/0x40 [omapdss]) from [<c02bfb94>] (bus_for_each_
dev+0x50/0x7c)
[ 2267.264678] [<c02bfb94>] (bus_for_each_dev+0x50/0x7c) from [<c02c287c>] (platform_pm_resume+0x2c/
0x50)
[ 2267.274566] [<c02c287c>] (platform_pm_resume+0x2c/0x50) from [<c02c6da8>] (dpm_run_callback.clone
.7+0x30/0xb0)
[ 2267.285186] [<c02c6da8>] (dpm_run_callback.clone.7+0x30/0xb0) from [<c02c7b2c>] (device_resume+0x
c8/0x188)
[ 2267.295471] [<c02c7b2c>] (device_resume+0xc8/0x188) from [<c02c7f54>] (dpm_resume+0xfc/0x21c)
[ 2267.304534] [<c02c7f54>] (dpm_resume+0xfc/0x21c) from [<c02c8208>] (dpm_resume_end+0xc/0x18)
[ 2267.313507] [<c02c8208>] (dpm_resume_end+0xc/0x18) from [<c007fbcc>] (suspend_devices_and_enter+0
x15c/0x2d0)
[ 2267.323913] [<c007fbcc>] (suspend_devices_and_enter+0x15c/0x2d0) from [<c007fecc>] (pm_suspend+0x
18c/0x208)
[ 2267.334259] [<c007fecc>] (pm_suspend+0x18c/0x208) from [<c007f170>] (state_store+0x120/0x134)
[ 2267.343292] [<c007f170>] (state_store+0x120/0x134) from [<c0262850>] (kobj_attr_store+0x14/0x20)
[ 2267.352661] [<c0262850>] (kobj_attr_store+0x14/0x20) from [<c0169b6c>] (sysfs_write_file+0x100/0x
184)
[ 2267.362457] [<c0169b6c>] (sysfs_write_file+0x100/0x184) from [<c0109008>] (vfs_write+0xb4/0x148)
[ 2267.371795] [<c0109008>] (vfs_write+0xb4/0x148) from [<c0109290>] (sys_write+0x40/0x70)
[ 2267.380310] [<c0109290>] (sys_write+0x40/0x70) from [<c0013d60>] (ret_fast_syscall+0x0/0x3c)
[ 2267.389282] ---[ end trace 54fe7eea726ac84d ]---
[ 2267.394592] dpm_run_callback(): platform_pm_resume+0x0/0x50 returns -13
[ 2267.401641] PM: Device omapdss failed to resume: error -13

I don't remember seeing that with earlier kernel versions, but I'm not
100% sure.

Looking at the log, I can see that both DSS and DISPC runtime_resume
callbacks are called early, and successfully. Later the system resume
callback tries to enable the displays that were enabled when the system
went to suspend, which fails because dispc_runtime_get() returns -EACCES
(and pm_runtime_enabled() returns false).

Interestingly, during suspend dispc_runtime_put() is called, and at that
point pm_runtime_enabled() also returns false, but pm_runtime_put_sync()
still returns 0 instead of -EACCES.

I'll need to study this more, but I don't think this is a problem
related to omapdss's handling of runtime PM, but rather handling system
suspend. omapdss's handling of system suspend is in a rather bad state.

 Tomi


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