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Date: Fri, 19 Apr 2013 19:34:49 +0530 From: Sourav Poddar <sourav.poddar@...com> To: Grygorii Strashko <grygorii.strashko@...com> CC: Kevin Hilman <khilman@...aro.org>, <gregkh@...uxfoundation.org>, <tony@...mide.com>, <rmk+kernel@....linux.org.uk>, <linux-serial@...r.kernel.org>, <linux-omap@...r.kernel.org>, <linux-kernel@...r.kernel.org>, Santosh Shilimkar <santosh.shilimkar@...com>, Felipe Balbi <balbi@...com>, Rajendra nayak <rnayak@...com> Subject: Re: [PATCH 0/6] Serial Omap fixes and cleanups Hi Grygorii, On Friday 19 April 2013 05:32 PM, Grygorii Strashko wrote: > On 04/18/2013 10:17 PM, Sourav Poddar wrote: >> Hi Kevin, >> On Thursday 18 April 2013 11:53 PM, Kevin Hilman wrote: >>> Hi Sourav, >>> >>> Sourav Poddar<sourav.poddar@...com> writes: >>> >>>> Hi, >>>> >>>> This patch series contains fixes and cleanups around the issue that >>>> the console UART should not idled on suspend while using >>>> "no_console_suspend" >>>> in bootargs. >>>> >>> The direction of the series is right, thanks for the updated approach. >>> I had a comple minor comments on specific patches, but the ordering of >>> the series needs a little tweaking. It should be >>> >>> - core/driver changes [current 1-3/6 are ok] >>> - remove usage from mach-omap2/serial.c (currently part of 4/6) >>> - remove am33x DT usage (current 5/6 is ok) >>> - remove entirely from omap_device (omap_device part of 4/6 and 6/6 >>> should be combined) >>> >> Thanks a lot for your review and comments. >> I have replied to your comments on the respective patches. >> Will take care of the "ordering" which you mentioned above >> in the next version. >> >> Thanks >> Sourav > Hi Sourav > > I'd like to clarify some points regarding this series: > > 1) I'm not sure that removing OMAP_DEVICE_NO_IDLE_ON_SUSPEND is fine. > FYI - > review.omapzoom.org/#/q/status:open,n,zI9e21bf4432a537a4ccb217cf9c425b0e4e499ce8 > "ASoC: omap-abe: Allow no idle on suspend" > The above "voice call" use case allows Audio playback while system is > in "suspend" state. > In addition HSI and SmartReflex may need to be active after > suspend_noirq stage. > By removing this flag such functionality will be broken (in case of > porting it > on newest Kernel or MainLine). > So, How it can be handled without OMAP_DEVICE_NO_IDLE_ON_SUSPEND? > Yes, if we have other use cases, we need to see if there is any way of handling it through the respective drivers. > 2) Runtime PM vs System suspend > - The commit 88d26136a "PM: Prevent runtime suspend during system resume" > block pm_runtime_put_xx() while suspending/resuming, so if your UART > will became active > (at least one call to pm_runtime_get_xx()) while system is > suspending it will stay active > until suspend_noirq stage. > - At suspend_noirq stage OMAP device framework will finally (brutally) > disable it to reach > system suspend state (in _od_suspend_noirq). > - At resume_noirq stage OMAP device framework will re-enable device if > it was disabled in > _od_suspend_noirq() to keep device state and Runtime PM in sync. > - In addition, the commit 9f6d8f6 "PM: Move disabling/enabling runtime > PM to late suspend/early resume" > will disable Runtime PM at suspend_late and enable it resume_early > stages. > > As, result: > - serial_omap_prepare()/serial_omap_complete() not needed - usually > console is active. > Or you may call pm_runtime_get_xxx() in serial_omap_prepare() to be > sure (that's all) > - removing OMAP_DEVICE_NO_IDLE_ON_SUSPEND will not help, because to > handle your use case > omap_device_idle() need to be removed from od_suspend_noirq(). > !! Which, in turn, will kill OMAP suspend !! (see Kevin's comments) > Yes, I have seen kevin's comments and indeed we need to remove "omap_device_idle" along with prep/complete to get my issue fixed(which indeed is not correct). > Unfortunately, I see no way to avoid usage > OMAP_DEVICE_NO_IDLE_ON_SUSPEND with the current > OMAP device framework. > > Regards, > -grygorii >>> Kevin >>> >>>> The approach thought of is to modify the serial core/serial driver >>>> to bypass >>>> runtime PM if the UART in contention is a console and we are using >>>> "no_console_suspend" >>>> in our bootargs. >>>> >>>> While fixing the above issue, there are other cleanups also done as >>>> part of >>>> this series which are no longer required. This cleanups mainly >>>> include getting >>>> rid of using "omap_device_disable_idle_on_suspend" api for both dt >>>> and non dt case >>>> as the serial driver will be self sufficient to handle the >>>> "no_idle_on_suspend" issue. >>>> Serial was the only one making use of >>>> "omap_device_disable_idle_on_suspend" >>>> >>>> Test info (except drivers: serial: mpc52xx_uart: Remove >>>> "uart_console" defintion): >>>> Omap4430sdp: >>>> - Tested wakeup from UART after suspend for dt and non dt case. >>>> Omap5430evm: >>>> - Tested wakeup from UART after suspend for dt case. >>>> >>>> >>>> There were discussions about how to handle "no_idle_on_suspend" >>>> issue and all the >>>> discussions are as follows: >>>> [v3]: https://lkml.org/lkml/2013/4/5/239 >>>> [v2]: https://lkml.org/lkml/2013/4/2/350 >>>> [v1]: https://lkml.org/lkml/2013/3/18/199 >>>> https://lkml.org/lkml/2013/3/18/295 >>>> Due to the amount of change in approach and other cleanups coming >>>> around it, I am posting >>>> this as a new series. >>>> >>>> This patches are based on 3.9-rc3 custom tree which has >>>> Santosh Shilimkar serial patch[1] >>>> [1]: http://permalink.gmane.org/gmane.linux.ports.arm.omap/95828 >>>> >>>> Cc: Santosh Shilimkar<santosh.shilimkar@...com> >>>> Cc: Felipe Balbi<balbi@...com> >>>> Cc: Rajendra nayak<rnayak@...com> >>>> >>>> Sourav Poddar (6): >>>> drivers: tty: serial: Move "uart_console" def to core header file. >>>> drivers: serial: mpc52xx_uart: Remove "uart_console" defintion >>>> driver: serial: omap: add prepare/complete callback for >>>> "no_console_suspend" case >>>> arm: mach-omap2: remove "OMAP_DEVICE_NO_IDLE_ON_SUSPEND" check >>>> arm: dts: am33xx: Remove "ti,no_idle_on_suspend" property. >>>> arm: mach-omap2: Remove "no_console_suspend" >>>> >>>> arch/arm/boot/dts/am33xx.dtsi | 1 - >>>> arch/arm/mach-omap2/omap_device.c | 10 +--------- >>>> arch/arm/mach-omap2/serial.c | 7 ------- >>>> drivers/tty/serial/mpc52xx_uart.c | 10 ---------- >>>> drivers/tty/serial/omap-serial.c | 20 ++++++++++++++++++++ >>>> drivers/tty/serial/serial_core.c | 6 ------ >>>> include/linux/serial_core.h | 6 ++++++ >>>> 7 files changed, 27 insertions(+), 33 deletions(-) >> >> -- >> To unsubscribe from this list: send the line "unsubscribe linux-omap" in >> the body of a message to majordomo@...r.kernel.org >> More majordomo info at http://vger.kernel.org/majordomo-info.html > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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