linux-kernel - Re: [PATCH 1/5] drm/omap: Fix suspend resume regression after platform data removal

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Message-ID: <16ba1808-5c7f-573d-8dd0-c80cac2f476e@ti.com>
Date:   Wed, 3 Jun 2020 15:33:43 +0300
From:   Tomi Valkeinen <tomi.valkeinen@...com>
To:     Tony Lindgren <tony@...mide.com>, <linux-omap@...r.kernel.org>
CC:     "Andrew F . Davis" <afd@...com>, Dave Gerlach <d-gerlach@...com>,
        Faiz Abbas <faiz_abbas@...com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Grygorii Strashko <grygorii.strashko@...com>,
        Keerthy <j-keerthy@...com>, Nishanth Menon <nm@...com>,
        Peter Ujfalusi <peter.ujfalusi@...com>,
        Roger Quadros <rogerq@...com>, Suman Anna <s-anna@...com>,
        Tero Kristo <t-kristo@...com>, <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <dri-devel@...ts.freedesktop.org>,
        Laurent Pinchart <laurent.pinchart@...asonboard.com>
Subject: Re: [PATCH 1/5] drm/omap: Fix suspend resume regression after
 platform data removal

Hi Tony,

On 31/05/2020 22:39, Tony Lindgren wrote:
> When booting without legacy platform data, we no longer have omap_device
> calling PM runtime suspend for us on suspend. This causes the driver
> context not be saved as we have no suspend and resume functions defined.
> 
> Let's fix the issue by switching over to use UNIVERSAL_DEV_PM_OPS as it
> will call the existing PM runtime suspend functions on suspend.

I don't think we can use UNIVERSAL_DEV_PM_OPS, as we can't disable DSS modules in any order, but 
things have to be shut down in orderly manner.

omapdrm hasn't relied on omap_device calling runtime suspend for us (I didn't know it does that). We 
have system suspend hooks in omap_drv.c:

SIMPLE_DEV_PM_OPS(omapdrm_pm_ops, omap_drm_suspend, omap_drm_resume)

omap_drm_suspend() is supposed to turn off the displays, which then cause dispc_runtime_put (and 
other runtime_puts) to be called, which result in dispc_runtime_suspend (and other runtime PM suspends).

So... For some reason that's no longer happening? I need to try to find a board with which 
suspend/resume works (without DSS)...

  Tomi

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