RE: OMAP:DSS: possible bug in WAITFOR_VSYNC ioctl

-----Original Message-----
From: Hiremath, Vaibhav
Sent: Friday, November 26, 2010 5:34 PM
To: 'Måns Rullgård'; linux-omap@vger.kernel.org
Subject: RE: OMAP:DSS: possible bug in WAITFOR_VSYNC ioctl

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-----Original Message-----
From: linux-omap-owner@vger.kernel.org [mailto:linux-omap-
owner@vger.kernel.org] On Behalf Of Måns Rullgård
Sent: Friday, November 26, 2010 2:09 PM
To: linux-omap@vger.kernel.org
Subject: Re: OMAP:DSS: possible bug in WAITFOR_VSYNC ioctl

"Hiremath, Vaibhav" [off-list ref] writes:

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-----Original Message-----
From: Ville Syrjälä [mailto:ville.syrjala@nokia.com]
Sent: Wednesday, November 24, 2010 10:01 PM
To: Hiremath, Vaibhav
Cc: Tomi Valkeinen; linux-omap@vger.kernel.org
Subject: Re: OMAP:DSS: possible bug in WAITFOR_VSYNC ioctl

On Wed, Nov 24, 2010 at 03:39:44PM +0530, ext Hiremath, Vaibhav

wrote:

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-----Original Message-----
From: Tomi Valkeinen [mailto:tomi.valkeinen@nokia.com]
Sent: Wednesday, November 24, 2010 2:28 PM
To: Hiremath, Vaibhav
Cc: linux-omap@vger.kernel.org
Subject: Re: OMAP:DSS: possible bug in WAITFOR_VSYNC ioctl

On Tue, 2010-11-23 at 23:46 +0530, ext Hiremath, Vaibhav wrote:

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Hi,

<snip>

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<snip..>

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As far as WAITFORGO is concerned, I think GO bit concept is
something OMAP notion/term and doesn't make sense to standardize
it. Atleast I am not aware of any other architecture having GO bit.

Naming is minor detail.  Feel free to suggest a better one.

[Hiremath, Vaibhav] If I fail to convince on this, then I think the only
left option is to make WAITFORGO ioctl generic. And put a disclaimer on
WAITFORVSYNC, it must not be used in panning use-case.

[Hiremath, Vaibhav] Also let me bring another point here,

If I understand correctly most of the application libraries (DirectFB, X, etc..) does use FBIO_WAITFORVSYNC to synchronize with HW, and manage ping pong mechanism.

With this finding, in case of OMAP3 we have to use OMAPFB_WAITFORGO (breaking standard applications).

Thanks,
Vaibhav

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--
Måns Rullgård
mans@mansr.com

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