[RFC 1/2] PM / Domains: Power on domain early during system resume
On 11/03/2014 06:13 PM, Kevin Hilman wrote:
> Andrzej Hajda writes:
>
>> On 10/30/2014 08:36 AM, Krzysztof Kozlowski wrote:
>>> On Åro, 2014-10-29 at 10:46 -0700, Kevin Hilman wrote:
Krzysztof Kozlowski writes:
> When resuming the system the power domain has to be powered on early so
> any runtime PM aware devices could resume.
>
> This fixes following scenario reproduced on Exynos DRM:
> 1. Power domain is off before suspending the system.
> 2. System is suspended to RAM.
> 3. Resuming starts. The Exynos DRM driver resume callback is called.
> 4. The Exynos DRM driver calls drm_helper_resume_force_mode which turns
> the screen on by calling exynos_dsi_dpms with DRM_MODE_DPMS_ON.
Dumb Q: if the device (and power domain) were off before (and during)
suspend, why are they being resumed?
Shouldn't the resume path restore things to the same state they were
before suspend?
>>> One could expect that... but the Exynos DRM driver behaves differently
>>> (and some other drivers also). In resume method it calls
>>> drm_helper_resume_force_mode() which forces restoring mode setting
>>> configuration. Apparently setting a mode needs DPMS on:
>>> static void exynos_drm_crtc_commit(struct drm_crtc *crtc)
>>> {
>>> ...
>>> exynos_drm_crtc_dpms(crtc, DRM_MODE_DPMS_ON);
>>> ...
>>>
>>> The previous DPMS status (status during suspend) is completely ignored
>>> here.
>>
>> Suspend callback switches off all connectors (thus all other devs in
>> their pipeline) by calling dpms_off,
>> in restore callback all devs are restored to their previous state by
>> calling appropriate dpms.
>> So I guess drm_helper_resume_force_mode() call at the end of resume is
>> incorrect.
>
> Though I'm not terribly familiar with DRM, it seems incorrect because I
> expect resume to restore the state of things when suspend happened, not
> forcibly resume everything.
>
>> On the other side it is present in many other drivers, so I am also
>> little bit confused.
>
> Many other DRM drivers? or other drivers too?
If I understand GPD code right :)
There is "small" problem :( Now if PM domain is OFF before suspend
- it's prohibited to turn it on during suspending/resuming.
commit 596ba34bcd2978ee9823cc1d84df230576f8ffb9
PM / Domains: System-wide transitions support for generic domains (v5)
But, it is possible to have devices which supports few power states, like:
on, sleep/low power, off (for example OMAP devices and also I saw this
for some I2C devices - can recollect only that it was some sensor and
touchscreen).
In normal operational mode Runtime PM switches device between on and sleep/low
power states,
but during suspend device need to be woken up and reconfigured to off state.
Also I found, that It looks like due to continuous refactoring the call of
pm_generic_suspend_noirq(dev) was finally dropped from pm_genpd_suspend_noirq(),
so .suspend_noirq() callback will never be called for devices from GPD.
Seems, that is the problem which this patch tries to fix and looks like there
are
will be more such kind of report as GPD is become used widely.
regards,
-grygorii
[RFC 1/2] PM / Domains: Power on domain early during system resume
Andrzej Hajda writes:
> On 10/30/2014 08:36 AM, Krzysztof Kozlowski wrote:
>> On Åro, 2014-10-29 at 10:46 -0700, Kevin Hilman wrote:
>>> Krzysztof Kozlowski writes:
>>>
When resuming the system the power domain has to be powered on early so
any runtime PM aware devices could resume.
This fixes following scenario reproduced on Exynos DRM:
1. Power domain is off before suspending the system.
2. System is suspended to RAM.
3. Resuming starts. The Exynos DRM driver resume callback is called.
4. The Exynos DRM driver calls drm_helper_resume_force_mode which turns
the screen on by calling exynos_dsi_dpms with DRM_MODE_DPMS_ON.
>>> Dumb Q: if the device (and power domain) were off before (and during)
>>> suspend, why are they being resumed?
>>>
>>> Shouldn't the resume path restore things to the same state they were
>>> before suspend?
>> One could expect that... but the Exynos DRM driver behaves differently
>> (and some other drivers also). In resume method it calls
>> drm_helper_resume_force_mode() which forces restoring mode setting
>> configuration. Apparently setting a mode needs DPMS on:
>> static void exynos_drm_crtc_commit(struct drm_crtc *crtc)
>> {
>> ...
>> exynos_drm_crtc_dpms(crtc, DRM_MODE_DPMS_ON);
>> ...
>>
>> The previous DPMS status (status during suspend) is completely ignored
>> here.
>
> Suspend callback switches off all connectors (thus all other devs in
> their pipeline) by calling dpms_off,
> in restore callback all devs are restored to their previous state by
> calling appropriate dpms.
> So I guess drm_helper_resume_force_mode() call at the end of resume is
> incorrect.
Though I'm not terribly familiar with DRM, it seems incorrect because I
expect resume to restore the state of things when suspend happened, not
forcibly resume everything.
> On the other side it is present in many other drivers, so I am also
> little bit confused.
Many other DRM drivers? or other drivers too?
Kevin
[RFC 1/2] PM / Domains: Power on domain early during system resume
On 10/30/2014 08:36 AM, Krzysztof Kozlowski wrote:
> On Åro, 2014-10-29 at 10:46 -0700, Kevin Hilman wrote:
>> Krzysztof Kozlowski writes:
>>
>>> When resuming the system the power domain has to be powered on early so
>>> any runtime PM aware devices could resume.
>>>
>>> This fixes following scenario reproduced on Exynos DRM:
>>> 1. Power domain is off before suspending the system.
>>> 2. System is suspended to RAM.
>>> 3. Resuming starts. The Exynos DRM driver resume callback is called.
>>> 4. The Exynos DRM driver calls drm_helper_resume_force_mode which turns
>>>the screen on by calling exynos_dsi_dpms with DRM_MODE_DPMS_ON.
>> Dumb Q: if the device (and power domain) were off before (and during)
>> suspend, why are they being resumed?
>>
>> Shouldn't the resume path restore things to the same state they were
>> before suspend?
> One could expect that... but the Exynos DRM driver behaves differently
> (and some other drivers also). In resume method it calls
> drm_helper_resume_force_mode() which forces restoring mode setting
> configuration. Apparently setting a mode needs DPMS on:
> static void exynos_drm_crtc_commit(struct drm_crtc *crtc)
> {
> ...
> exynos_drm_crtc_dpms(crtc, DRM_MODE_DPMS_ON);
> ...
>
> The previous DPMS status (status during suspend) is completely ignored
> here.
Suspend callback switches off all connectors (thus all other devs in
their pipeline) by calling dpms_off,
in restore callback all devs are restored to their previous state by
calling appropriate dpms.
So I guess drm_helper_resume_force_mode() call at the end of resume is
incorrect.
On the other side it is present in many other drivers, so I am also
little bit confused.
Regards
Andrzej
[RFC 1/2] PM / Domains: Power on domain early during system resume
On Åro, 2014-10-29 at 10:46 -0700, Kevin Hilman wrote:
> Krzysztof Kozlowski writes:
>
> > When resuming the system the power domain has to be powered on early so
> > any runtime PM aware devices could resume.
> >
> > This fixes following scenario reproduced on Exynos DRM:
> > 1. Power domain is off before suspending the system.
> > 2. System is suspended to RAM.
> > 3. Resuming starts. The Exynos DRM driver resume callback is called.
> > 4. The Exynos DRM driver calls drm_helper_resume_force_mode which turns
> >the screen on by calling exynos_dsi_dpms with DRM_MODE_DPMS_ON.
>
> Dumb Q: if the device (and power domain) were off before (and during)
> suspend, why are they being resumed?
>
> Shouldn't the resume path restore things to the same state they were
> before suspend?
One could expect that... but the Exynos DRM driver behaves differently
(and some other drivers also). In resume method it calls
drm_helper_resume_force_mode() which forces restoring mode setting
configuration. Apparently setting a mode needs DPMS on:
static void exynos_drm_crtc_commit(struct drm_crtc *crtc)
{
...
exynos_drm_crtc_dpms(crtc, DRM_MODE_DPMS_ON);
...
The previous DPMS status (status during suspend) is completely ignored
here.
I dunno why... maybe someone from DRM could share some thoughts?
Best regards,
Krzysztof
[RFC 1/2] PM / Domains: Power on domain early during system resume
Krzysztof Kozlowski writes: > When resuming the system the power domain has to be powered on early so > any runtime PM aware devices could resume. > > This fixes following scenario reproduced on Exynos DRM: > 1. Power domain is off before suspending the system. > 2. System is suspended to RAM. > 3. Resuming starts. The Exynos DRM driver resume callback is called. > 4. The Exynos DRM driver calls drm_helper_resume_force_mode which turns >the screen on by calling exynos_dsi_dpms with DRM_MODE_DPMS_ON. Dumb Q: if the device (and power domain) were off before (and during) suspend, why are they being resumed? Shouldn't the resume path restore things to the same state they were before suspend? Kevin
[RFC 1/2] PM / Domains: Power on domain early during system resume
On czw, 2014-10-23 at 19:20 +0300, Grygorii Strashko wrote: > Hi Krzysztof, > > On 10/23/2014 04:48 PM, Krzysztof Kozlowski wrote: > > When resuming the system the power domain has to be powered on early so > > any runtime PM aware devices could resume. > > > > This fixes following scenario reproduced on Exynos DRM: > > 1. Power domain is off before suspending the system. > > 2. System is suspended to RAM. > > 3. Resuming starts. The Exynos DRM driver resume callback is called. > > 4. The Exynos DRM driver calls drm_helper_resume_force_mode which turns > > the screen on by calling exynos_dsi_dpms with DRM_MODE_DPMS_ON. > > 5. The Exynos DSI driver calls pm_runtime_get. The driver runtime > > resumes and this should turn LCD power domain on. > > 6. Unfortunately the domain cannot be turned on because system resume is > > in progress and genpd->prepared_count is positive. > > Just interesting, what value will be returned by pm_runtime_enabled() > from any of your .resume() callback (for any device which belongs to > some Generic PM domain)? exynos_drm_resume: false exynos_dsi_enable: true Full backtrace leading to exynos_dsi_enable: [ 37.944830] [ cut here ] [ 37.944860] WARNING: CPU: 0 PID: 3125 at drivers/gpu/drm/exynos/exynos_drm_dsi.c:1360 exynos_dsi_dpms+0xc0/0x398() [ 37.944869] Modules linked in: [ 37.944883] CPU: 0 PID: 3125 Comm: bash Tainted: GW 3.17.0-next-20141020-00050-g844ed80678d5-dirty #479 [ 37.944923] [] (unwind_backtrace) from [] (show_stack+0x10/0x14) [ 37.944949] [] (show_stack) from [] (dump_stack+0x70/0xbc) [ 37.944977] [] (dump_stack) from [] (warn_slowpath_common+0x64/0x88) [ 37.944992] [] (warn_slowpath_common) from [] (warn_slowpath_null+0x1c/0x24) [ 37.945011] [] (warn_slowpath_null) from [] (exynos_dsi_dpms+0xc0/0x398) [ 37.945024] [] (exynos_dsi_dpms) from [] (exynos_drm_encoder_commit+0x24/0x40) [ 37.945044] [] (exynos_drm_encoder_commit) from [] (drm_crtc_helper_set_mode+0x400/0x4e8) [ 37.945057] [] (drm_crtc_helper_set_mode) from [] (drm_helper_resume_force_mode+0x68/0x124) [ 37.945083] [] (drm_helper_resume_force_mode) from [] (exynos_drm_resume+0x80/0x90) [ 37.945100] [] (exynos_drm_resume) from [] (platform_pm_resume+0x2c/0x4c) [ 37.945118] [] (platform_pm_resume) from [] (dpm_run_callback.isra.7+0x2c/0x64) [ 37.945130] [] (dpm_run_callback.isra.7) from [] (device_resume+0xac/0x180) [ 37.945141] [] (device_resume) from [] (dpm_resume+0xe8/0x20c) [ 37.945152] [] (dpm_resume) from [] (dpm_resume_end+0xc/0x18) [ 37.945175] [] (dpm_resume_end) from [] (suspend_devices_and_enter+0x230/0x3c8) [ 37.945190] [] (suspend_devices_and_enter) from [] (pm_suspend+0x268/0x29c) [ 37.945202] [] (pm_suspend) from [] (state_store+0x6c/0xbc) [ 37.945220] [] (state_store) from [] (kobj_attr_store+0x14/0x20) [ 37.945235] [] (kobj_attr_store) from [] (sysfs_kf_write+0x44/0x48) [ 37.945245] [] (sysfs_kf_write) from [] (kernfs_fop_write+0xc0/0x17c) [ 37.945268] [] (kernfs_fop_write) from [] (vfs_write+0xa0/0x1a8) [ 37.945282] [] (vfs_write) from [] (SyS_write+0x40/0x8c) [ 37.945299] [] (SyS_write) from [] (ret_fast_syscall+0x0/0x30) [ 37.945307] ---[ end trace e930e0edfd9a5ad2 ]--- > I'm asking, because as I can see Runtime PM can be disabled from > pm_genpd_prepare(). > > Thank you. > > Oh. I've just found that you might get this issue if you will try to do > suspend when PM domain is ON ;) > > Any way, In my opinion, It might be better to fix pm_genpd_prepare() so > it will not increment prepared_count when initial state of the GPD is > GPD_STATE_POWER_OFF. Seems it's needed only in opposite case - > when state of GPD has to be restored from pm_genpd_resume_noirq(). That sounds good but what about cases when the device will runtime resume during suspend (early at suspend)? Actually I seen this with framebuffer console. Right after starting suspend the console is flushed and poked which leads to powering on LCD. Best regards, Krzysztof
[RFC 1/2] PM / Domains: Power on domain early during system resume
Hi Krzysztof,
On 10/23/2014 04:48 PM, Krzysztof Kozlowski wrote:
> When resuming the system the power domain has to be powered on early so
> any runtime PM aware devices could resume.
>
> This fixes following scenario reproduced on Exynos DRM:
> 1. Power domain is off before suspending the system.
> 2. System is suspended to RAM.
> 3. Resuming starts. The Exynos DRM driver resume callback is called.
> 4. The Exynos DRM driver calls drm_helper_resume_force_mode which turns
> the screen on by calling exynos_dsi_dpms with DRM_MODE_DPMS_ON.
> 5. The Exynos DSI driver calls pm_runtime_get. The driver runtime
> resumes and this should turn LCD power domain on.
> 6. Unfortunately the domain cannot be turned on because system resume is
> in progress and genpd->prepared_count is positive.
Just interesting, what value will be returned by pm_runtime_enabled()
from any of your .resume() callback (for any device which belongs to
some Generic PM domain)?
I'm asking, because as I can see Runtime PM can be disabled from
pm_genpd_prepare().
Thank you.
Oh. I've just found that you might get this issue if you will try to do
suspend when PM domain is ON ;)
Any way, In my opinion, It might be better to fix pm_genpd_prepare() so
it will not increment prepared_count when initial state of the GPD is
GPD_STATE_POWER_OFF. Seems it's needed only in opposite case -
when state of GPD has to be restored from pm_genpd_resume_noirq().
>
> Steps to reproduce:
> 1. Add runtime PM to Exynos DSI driver.
> 2. Build Exynos DRM/FB without FRAMEBUFFER_CONSOLE.
> 3. Enable the connector and screen (e.g. with modeset-vsync application).
> 4. echo 3 > /sys/devices/platform/exynos-drm/graphics/fb0/blank
> 5. echo mem > /sys/power/state
> 6. Resume.
> [ 77.712469] PM: early resume of devices complete after 3.854 msecs
> [ 77.712739] exynos-dsi 11c8.dsi: pm_genpd_resume()
> [ 77.712758] exynos4-fimc 1180.fimc: pm_genpd_resume()
> [ 77.712774] exynos4-fimc 1181.fimc: pm_genpd_resume()
> [ 77.712787] exynos-drm-fimc 1182.fimc: pm_genpd_resume()
> [ 77.712802] exynos-drm-fimc 1183.fimc: pm_genpd_resume()
> [ 77.712815] s5p-mipi-csis 1188.csis: pm_genpd_resume()
> [ 77.712829] s5p-mipi-csis 1189.csis: pm_genpd_resume()
> [ 77.712843] exynos-fimc-lite 1239.fimc-lite: pm_genpd_resume()
> [ 77.712856] exynos-fimc-lite 123a.fimc-lite: pm_genpd_resume()
> [ 77.713788] exynos4-fb 11c0.fimd: pm_genpd_resume()
> [ 77.713912] wake disabled for irq 184
> [ 77.713923] wake disabled for irq 185
> [ 77.714082] wake disabled for irq 173
> [ 77.715676] wake disabled for irq 176
> [ 77.718540] exynos4-fb 11c0.fimd: pm_genpd_runtime_resume()
> [ 77.718567] exynos4-fb 11c0.fimd: state restore latency exceeded, new
> value 1708 ns
> [ 77.718636] exynos-dsi 11c8.dsi: pm_genpd_runtime_resume()
> [ 77.892366] exynos-dsi 11c8.dsi: PLL failed to stabilize
> [ 77.892377] exynos-dsi 11c8.dsi: failed to configure DSI PLL
> [ 78.192168] exynos-dsi 11c8.dsi: timeout waiting for reset
> [ 78.211578] exynos-dsi 11c8.dsi: waiting for bus lanes timed out
> [ 78.307173] exynos-dsi 11c8.dsi: xfer timed out: d1 00 (null)
> [ 78.307190] panel_s6e8aa0 11c8.dsi.0: error -110 reading dcs seq(0xd1)
> [ 78.307199] panel_s6e8aa0 11c8.dsi.0: read id failed
>
> Signed-off-by: Krzysztof Kozlowski
> ---
> drivers/base/power/domain.c | 3 +--
> 1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
> index 40bc2f4072cc..4fdfe404a04c 100644
> --- a/drivers/base/power/domain.c
> +++ b/drivers/base/power/domain.c
> @@ -179,8 +179,7 @@ static int __pm_genpd_poweron(struct generic_pm_domain
> *genpd)
> }
> finish_wait(>status_wait_queue, );
>
> - if (genpd->status == GPD_STATE_ACTIVE
> - || (genpd->prepared_count > 0 && genpd->suspend_power_off))
> + if (genpd->status == GPD_STATE_ACTIVE)
> return 0;
>
> if (genpd->status != GPD_STATE_POWER_OFF) {
>
regards,
-grygorii
[RFC 1/2] PM / Domains: Power on domain early during system resume
When resuming the system the power domain has to be powered on early so
any runtime PM aware devices could resume.
This fixes following scenario reproduced on Exynos DRM:
1. Power domain is off before suspending the system.
2. System is suspended to RAM.
3. Resuming starts. The Exynos DRM driver resume callback is called.
4. The Exynos DRM driver calls drm_helper_resume_force_mode which turns
the screen on by calling exynos_dsi_dpms with DRM_MODE_DPMS_ON.
5. The Exynos DSI driver calls pm_runtime_get. The driver runtime
resumes and this should turn LCD power domain on.
6. Unfortunately the domain cannot be turned on because system resume is
in progress and genpd->prepared_count is positive.
Steps to reproduce:
1. Add runtime PM to Exynos DSI driver.
2. Build Exynos DRM/FB without FRAMEBUFFER_CONSOLE.
3. Enable the connector and screen (e.g. with modeset-vsync application).
4. echo 3 > /sys/devices/platform/exynos-drm/graphics/fb0/blank
5. echo mem > /sys/power/state
6. Resume.
[ 77.712469] PM: early resume of devices complete after 3.854 msecs
[ 77.712739] exynos-dsi 11c8.dsi: pm_genpd_resume()
[ 77.712758] exynos4-fimc 1180.fimc: pm_genpd_resume()
[ 77.712774] exynos4-fimc 1181.fimc: pm_genpd_resume()
[ 77.712787] exynos-drm-fimc 1182.fimc: pm_genpd_resume()
[ 77.712802] exynos-drm-fimc 1183.fimc: pm_genpd_resume()
[ 77.712815] s5p-mipi-csis 1188.csis: pm_genpd_resume()
[ 77.712829] s5p-mipi-csis 1189.csis: pm_genpd_resume()
[ 77.712843] exynos-fimc-lite 1239.fimc-lite: pm_genpd_resume()
[ 77.712856] exynos-fimc-lite 123a.fimc-lite: pm_genpd_resume()
[ 77.713788] exynos4-fb 11c0.fimd: pm_genpd_resume()
[ 77.713912] wake disabled for irq 184
[ 77.713923] wake disabled for irq 185
[ 77.714082] wake disabled for irq 173
[ 77.715676] wake disabled for irq 176
[ 77.718540] exynos4-fb 11c0.fimd: pm_genpd_runtime_resume()
[ 77.718567] exynos4-fb 11c0.fimd: state restore latency exceeded, new
value 1708 ns
[ 77.718636] exynos-dsi 11c8.dsi: pm_genpd_runtime_resume()
[ 77.892366] exynos-dsi 11c8.dsi: PLL failed to stabilize
[ 77.892377] exynos-dsi 11c8.dsi: failed to configure DSI PLL
[ 78.192168] exynos-dsi 11c8.dsi: timeout waiting for reset
[ 78.211578] exynos-dsi 11c8.dsi: waiting for bus lanes timed out
[ 78.307173] exynos-dsi 11c8.dsi: xfer timed out: d1 00 (null)
[ 78.307190] panel_s6e8aa0 11c8.dsi.0: error -110 reading dcs seq(0xd1)
[ 78.307199] panel_s6e8aa0 11c8.dsi.0: read id failed
Signed-off-by: Krzysztof Kozlowski
---
drivers/base/power/domain.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
index 40bc2f4072cc..4fdfe404a04c 100644
--- a/drivers/base/power/domain.c
+++ b/drivers/base/power/domain.c
@@ -179,8 +179,7 @@ static int __pm_genpd_poweron(struct generic_pm_domain
*genpd)
}
finish_wait(>status_wait_queue, );
- if (genpd->status == GPD_STATE_ACTIVE
- || (genpd->prepared_count > 0 && genpd->suspend_power_off))
+ if (genpd->status == GPD_STATE_ACTIVE)
return 0;
if (genpd->status != GPD_STATE_POWER_OFF) {
--
1.9.1
