S5P-TV: Warning for regulator unbalanced disables

S5P-TV: Warning for regulator unbalanced disables

[Tushar Behera]

Hi,

After implementing genpd framework for EXYNOS4, (Ref commit 91cfbd4
"ARM: EXYNOS: Hook up power domains to generic power domain
infrastructure" in Kukjin's for-next branch), we are getting following
warning from s5p-hdmi driver.

The test was done on Origen board with code based on 3.3-rc4 and
Kukjin's for-next branch. [1]

------------[ cut here ]------------
WARNING: at drivers/regulator/core.c:1503 _regulator_disable+0xf8/0x164()
unbalanced disables for VMIPI_1.1V
Modules linked in:
regulator_init_complete: VDD_G3D_1.1V: incomplete constraints, leaving on
[<c0014624>] (unwind_backtrace+0x0/0xf8) from [<c00232fc>]
(warn_slowpath_common+0x54/0x64)
[<c00232fc>] (warn_slowpath_common+0x54/0x64) from [<c00233a0>]
(warn_slowpath_fmt+0x30/0x40)
[<c00233a0>] (warn_slowpath_fmt+0x30/0x40) from [<c01ab9b8>]
(_regulator_disable+0xf8/0x164)
[<c01ab9b8>] (_regulator_disable+0xf8/0x164) from [<c01aba40>]
(regulator_disable+0x1c/0x48)
[<c01aba40>] (regulator_disable+0x1c/0x48) from [<c01abcf4>]
(regulator_bulk_disable+0x24/0x8c)
regulator_init_complete: VADC_3.3V: incomplete constraints, leaving on
[<c01abcf4>] (regulator_bulk_disable+0x24/0x8c) from [<c028d874>]
(hdmi_runtime_suspend+0x28/0x30)
[<c028d874>] (hdmi_runtime_suspend+0x28/0x30) from [<c01edac4>]
(pm_genpd_default_save_state+0x48/0x5c)
[<c01edac4>] (pm_genpd_default_save_state+0x48/0x5c) from [<c01eeed4>]
(pm_genpd_poweroff+0x224/0x3f0)
[<c01eeed4>] (pm_genpd_poweroff+0x224/0x3f0) from [<c01ef190>]
(genpd_power_off_work_fn+0x1c/0x28)
[<c01ef190>] (genpd_power_off_work_fn+0x1c/0x28) from [<c0036ac0>]
(process_one_work+0x118/0x3b0)
regulator_init_complete: VMIPI_1.8V: incomplete constraints, leaving on
[<c0036ac0>] (process_one_work+0x118/0x3b0) from [<c0039424>]
(worker_thread+0x18c/0x3a0)
[<c0039424>] (worker_thread+0x18c/0x3a0) from [<c003d734>]
(kthread+0x8c/0x90)
[<c003d734>] (kthread+0x8c/0x90) from [<c000f278>]
(kernel_thread_exit+0x0/0x8)
---[ end trace 9e20783f432f4c81 ]---

[1] git://git.linaro.org/people/tushar/linux-linaro-samsung.git
(test/hdmi-pd)

-- 
Tushar Behera

RE: S5P-TV: Warning for regulator unbalanced disables

[Marek Szyprowski]

Hi Tushar,

On Thursday, February 23, 2012 5:43 AM You wrote:

> After implementing genpd framework for EXYNOS4, (Ref commit 91cfbd4
> "ARM: EXYNOS: Hook up power domains to generic power domain
> infrastructure" in Kukjin's for-next branch), we are getting following
> warning from s5p-hdmi driver.
>
> The test was done on Origen board with code based on 3.3-rc4 and
> Kukjin's for-next branch. [1]
>
> ------------[ cut here ]------------
> WARNING: at drivers/regulator/core.c:1503 _regulator_disable+0xf8/0x164()

(snipped)

Thanks for the report. We know about this issue. It is not really related to
regulators nor s5p-tv driver. There is something broken (or misused) in the
gen_pd driver and its implementation for Exysno4 hw. If you dig a bit into
the problem You can observe the following call sequence on device probe:

exynos4_genpd_enable()
s5p_tv_runtime_disable()
exynos4_genpd_disable()

So the call to s5p_tv_runtime_disable is not balanced with s5p_tv_runtime_resume()
what causes the error you have posted. It looks that runtime pw framework makes
some wrong assumptions about the state of the device once power domain has been
registered.

The same problem appears for s5p-fimc and s5p-mfc, although it is not observed
as kernel error, but these devices also suffers from it - their clocks get disabled
one time too much so they do not operate correctly.

We are investigating this issue further.

Best regards
--
Marek Szyprowski
Samsung Poland R&D Center


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