linux-kernel - Re: [PATCH v2 2/2] drm/exynos/dsi: Add runtime PM so LCD power domain could be turned off

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Message-id: <1415950378.25732.0.camel@AMDC1943>
Date:	Fri, 14 Nov 2014 08:32:58 +0100
From:	Krzysztof Kozlowski <k.kozlowski@...sung.com>
To:	Inki Dae <inki.dae@...sung.com>
Cc:	Joonyoung Shim <jy0922.shim@...sung.com>,
	Seung-Woo Kim <sw0312.kim@...sung.com>,
	Kyungmin Park <kyungmin.park@...sung.com>,
	David Airlie <airlied@...ux.ie>,
	Kukjin Kim <kgene.kim@...sung.com>,
	dri-devel@...ts.freedesktop.org,
	linux-arm-kernel@...ts.infradead.org,
	linux-samsung-soc@...r.kernel.org, linux-kernel@...r.kernel.org,
	Andrzej Hajda <a.hajda@...sung.com>,
	Marek Szyprowski <m.szyprowski@...sung.com>,
	Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
	Grygorii Strashko <grygorii.strashko@...com>,
	Kevin Hilman <khilman@...nel.org>
Subject: Re: [PATCH v2 2/2] drm/exynos/dsi: Add runtime PM so LCD power domain
 could be turned off

On pią, 2014-11-14 at 11:53 +0900, Inki Dae wrote:
> On 2014년 11월 07일 22:53, Krzysztof Kozlowski wrote:
> > Add runtime Power Management to the Exynos DSI driver so the LCD power
> > domain could be turned off.
> > 
> > This slightly reduces the energy consumption when screen is completely
> > turned off. On Trats2 board when the system was idle the energy
> > consumption dropped by 1% (from 92.2 mA to 91.1 mA).
> > 
> > Before the patch:
> > $ cat cat /sys/kernel/debug/pm_genpd/pm_genpd_summary
> > lcd0-power-domain               on
> >     /devices/11c00000.fimd                              suspended
> >     /devices/11c80000.dsi                               unsupported
> > 
> > After applying the patch:
> > lcd0-power-domain               off
> >     /devices/11c00000.fimd                              suspended
> >     /devices/11c80000.dsi                               suspended
> 
> Reasonable but this patch incurs page flip test timeout like below,
> # modetest -v -s 15@12:720x1280
> trying to open device 'i915'...failed.
> trying to open device 'radeon'...failed.
> trying to open device 'nouveau'...failed.
> trying to open device 'vmwgfx'...failed.
> trying to open device 'omapdrm'...failed.
> trying to open device 'exynos'...success.
> setting mode 720x1280-0Hz@...4 on connectors 15, crtc 12
> select timed out or error (ret 0)
> 
> I'm not sure why this issue is incurred with this patch even through
> this patch is reasonable and correct. So we need more checking.
> 
> P.S. I tested it on exynos-drm-next and m0 board.

Thanks for pointing this issue. I'll investigate it.

Best regards,
Krzysztof


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