From: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
To: Sascha Hauer <s.hauer-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>
Cc: linux-fbdev-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
David Airlie <airlied-cv59FeDIM0c@public.gmane.org>,
devicetree-discuss-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org,
Florian Tobias Schandinat
<FlorianSchandinat-Mmb7MZpHnFY@public.gmane.org>,
dri-devel-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org,
Tomi Valkeinen <tomi.valkeinen-l0cyMroinI0@public.gmane.org>,
kernel-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org,
Steffen Trumtrar
<s.trumtrar-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>,
Guennady Liakhovetski
<g.liakhovetski-Mmb7MZpHnFY@public.gmane.org>,
linux-media-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Subject: Re: [PATCH v12 3/6] fbmon: add videomode helpers
Date: Thu, 22 Nov 2012 08:50:10 +0000 [thread overview]
Message-ID: <1554720.pFHYnMF1G4@avalon> (raw)
In-Reply-To: <20121122062000.GW10369-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>
Hi Sascha,
On Thursday 22 November 2012 07:20:00 Sascha Hauer wrote:
> On Wed, Nov 21, 2012 at 11:02:44PM +0100, Laurent Pinchart wrote:
> > Hi Steffen,
> >
> > > +
> > > + htotal = vm->hactive + vm->hfront_porch + vm->hback_porch +
> > > + vm->hsync_len;
> > > + vtotal = vm->vactive + vm->vfront_porch + vm->vback_porch +
> > > + vm->vsync_len;
> > > + fbmode->refresh = (vm->pixelclock * 1000) / (htotal * vtotal);
> >
> > This will fail if vm->pixelclock >= ((1 << 32) / 1000). The easiest
> > solution is probably to use 64-bit computation.
>
> You have displays with a pixelclock > 4GHz?
vm->pixelclock is expressed in Hz. vm->pixelclock * 1000 will thus overflow if
the clock frequency is >= ~4.3 MHz. I have displays with a clock frequency
higher than that :-)
--
Regards,
Laurent Pinchart
WARNING: multiple messages have this Message-ID (diff)
From: Laurent Pinchart <laurent.pinchart-ryLnwIuWjnjg/C1BVhZhaw@public.gmane.org>
To: Sascha Hauer <s.hauer-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>
Cc: linux-fbdev-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
David Airlie <airlied-cv59FeDIM0c@public.gmane.org>,
devicetree-discuss-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org,
Florian Tobias Schandinat
<FlorianSchandinat-Mmb7MZpHnFY@public.gmane.org>,
dri-devel-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org,
Tomi Valkeinen <tomi.valkeinen-l0cyMroinI0@public.gmane.org>,
kernel-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org,
Steffen Trumtrar
<s.trumtrar-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>,
Guennady Liakhovetski
<g.liakhovetski-Mmb7MZpHnFY@public.gmane.org>,
linux-media-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Subject: Re: [PATCH v12 3/6] fbmon: add videomode helpers
Date: Thu, 22 Nov 2012 09:50:10 +0100 [thread overview]
Message-ID: <1554720.pFHYnMF1G4@avalon> (raw)
In-Reply-To: <20121122062000.GW10369-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>
Hi Sascha,
On Thursday 22 November 2012 07:20:00 Sascha Hauer wrote:
> On Wed, Nov 21, 2012 at 11:02:44PM +0100, Laurent Pinchart wrote:
> > Hi Steffen,
> >
> > > +
> > > + htotal = vm->hactive + vm->hfront_porch + vm->hback_porch +
> > > + vm->hsync_len;
> > > + vtotal = vm->vactive + vm->vfront_porch + vm->vback_porch +
> > > + vm->vsync_len;
> > > + fbmode->refresh = (vm->pixelclock * 1000) / (htotal * vtotal);
> >
> > This will fail if vm->pixelclock >= ((1 << 32) / 1000). The easiest
> > solution is probably to use 64-bit computation.
>
> You have displays with a pixelclock > 4GHz?
vm->pixelclock is expressed in Hz. vm->pixelclock * 1000 will thus overflow if
the clock frequency is >= ~4.3 MHz. I have displays with a clock frequency
higher than that :-)
--
Regards,
Laurent Pinchart
WARNING: multiple messages have this Message-ID (diff)
From: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
To: Sascha Hauer <s.hauer@pengutronix.de>
Cc: Steffen Trumtrar <s.trumtrar@pengutronix.de>,
devicetree-discuss@lists.ozlabs.org,
Rob Herring <robherring2@gmail.com>,
linux-fbdev@vger.kernel.org, dri-devel@lists.freedesktop.org,
Thierry Reding <thierry.reding@avionic-design.de>,
Guennady Liakhovetski <g.liakhovetski@gmx.de>,
linux-media@vger.kernel.org,
Tomi Valkeinen <tomi.valkeinen@ti.com>,
Stephen Warren <swarren@wwwdotorg.org>,
kernel@pengutronix.de,
Florian Tobias Schandinat <FlorianSchandinat@gmx.de>,
David Airlie <airlied@linux.ie>
Subject: Re: [PATCH v12 3/6] fbmon: add videomode helpers
Date: Thu, 22 Nov 2012 09:50:10 +0100 [thread overview]
Message-ID: <1554720.pFHYnMF1G4@avalon> (raw)
In-Reply-To: <20121122062000.GW10369@pengutronix.de>
Hi Sascha,
On Thursday 22 November 2012 07:20:00 Sascha Hauer wrote:
> On Wed, Nov 21, 2012 at 11:02:44PM +0100, Laurent Pinchart wrote:
> > Hi Steffen,
> >
> > > +
> > > + htotal = vm->hactive + vm->hfront_porch + vm->hback_porch +
> > > + vm->hsync_len;
> > > + vtotal = vm->vactive + vm->vfront_porch + vm->vback_porch +
> > > + vm->vsync_len;
> > > + fbmode->refresh = (vm->pixelclock * 1000) / (htotal * vtotal);
> >
> > This will fail if vm->pixelclock >= ((1 << 32) / 1000). The easiest
> > solution is probably to use 64-bit computation.
>
> You have displays with a pixelclock > 4GHz?
vm->pixelclock is expressed in Hz. vm->pixelclock * 1000 will thus overflow if
the clock frequency is >= ~4.3 MHz. I have displays with a clock frequency
higher than that :-)
--
Regards,
Laurent Pinchart
next prev parent reply other threads:[~2012-11-22 8:50 UTC|newest]
Thread overview: 97+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-11-20 15:54 [PATCH v12 0/6] of: add display helper Steffen Trumtrar
2012-11-20 15:54 ` Steffen Trumtrar
2012-11-20 15:54 ` [PATCH v12 1/6] video: add display_timing and videomode Steffen Trumtrar
2012-11-20 15:54 ` Steffen Trumtrar
[not found] ` <1353426896-6045-2-git-send-email-s.trumtrar-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>
2012-11-21 11:37 ` Tomi Valkeinen
2012-11-21 11:37 ` Tomi Valkeinen
2012-11-21 11:37 ` Tomi Valkeinen
2012-11-21 16:11 ` Steffen Trumtrar
2012-11-21 16:11 ` Steffen Trumtrar
[not found] ` <20121121161103.GA12657-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>
2012-11-21 16:42 ` Tomi Valkeinen
2012-11-21 16:42 ` Tomi Valkeinen
2012-11-21 16:42 ` Tomi Valkeinen
2012-11-20 15:54 ` [PATCH v12 2/6] video: add of helper for videomode Steffen Trumtrar
2012-11-20 15:54 ` Steffen Trumtrar
[not found] ` <1353426896-6045-3-git-send-email-s.trumtrar-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>
2012-11-21 10:12 ` Manjunathappa, Prakash
2012-11-21 10:12 ` Manjunathappa, Prakash
2012-11-21 10:12 ` Manjunathappa, Prakash
2012-11-21 11:48 ` Steffen Trumtrar
2012-11-21 11:48 ` Steffen Trumtrar
2012-11-21 11:52 ` Thierry Reding
2012-11-21 11:52 ` Thierry Reding
2012-11-21 15:03 ` Rob Herring
2012-11-21 15:03 ` Rob Herring
[not found] ` <50ACED4A.5040806-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2012-11-21 15:13 ` Thierry Reding
2012-11-21 15:13 ` Thierry Reding
2012-11-21 15:13 ` Thierry Reding
2012-11-22 9:10 ` Steffen Trumtrar
2012-11-22 9:10 ` Steffen Trumtrar
2012-11-22 9:10 ` Steffen Trumtrar
2012-11-21 12:22 ` Tomi Valkeinen
2012-11-21 12:22 ` Tomi Valkeinen
2012-11-21 12:22 ` Tomi Valkeinen
2012-11-20 15:54 ` [PATCH v12 4/6] fbmon: add of_videomode helpers Steffen Trumtrar
2012-11-20 15:54 ` Steffen Trumtrar
[not found] ` <1353426896-6045-5-git-send-email-s.trumtrar-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>
2012-11-21 12:49 ` Tomi Valkeinen
2012-11-21 12:49 ` Tomi Valkeinen
2012-11-21 12:49 ` Tomi Valkeinen
2012-11-21 13:08 ` Laurent Pinchart
2012-11-21 13:08 ` Laurent Pinchart
2012-11-21 16:24 ` Steffen Trumtrar
2012-11-21 16:24 ` Steffen Trumtrar
2012-11-21 16:47 ` Tomi Valkeinen
2012-11-21 16:47 ` Tomi Valkeinen
2012-11-21 16:47 ` Tomi Valkeinen
2012-11-20 15:54 ` [PATCH v12 5/6] drm_modes: add videomode helpers Steffen Trumtrar
2012-11-20 15:54 ` Steffen Trumtrar
2012-11-21 12:50 ` Tomi Valkeinen
2012-11-21 12:50 ` Tomi Valkeinen
2012-11-21 12:50 ` Tomi Valkeinen
[not found] ` <1353426896-6045-1-git-send-email-s.trumtrar-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>
2012-11-20 15:54 ` [PATCH v12 3/6] fbmon: " Steffen Trumtrar
2012-11-20 15:54 ` Steffen Trumtrar
2012-11-20 15:54 ` Steffen Trumtrar
2012-11-21 10:09 ` Manjunathappa, Prakash
2012-11-21 11:09 ` Leela Krishna Amudala
2012-11-21 11:21 ` Leela Krishna Amudala
2012-11-21 11:58 ` Steffen Trumtrar
2012-11-21 11:58 ` Steffen Trumtrar
2012-11-21 12:27 ` Tomi Valkeinen
2012-11-21 12:27 ` Tomi Valkeinen
2012-11-21 12:27 ` Tomi Valkeinen
[not found] ` <1353426896-6045-4-git-send-email-s.trumtrar-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>
2012-11-21 22:02 ` Laurent Pinchart
2012-11-21 22:02 ` Laurent Pinchart
2012-11-21 22:02 ` Laurent Pinchart
2012-11-22 6:20 ` Sascha Hauer
2012-11-22 6:20 ` Sascha Hauer
2012-11-22 6:20 ` Sascha Hauer
[not found] ` <20121122062000.GW10369-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>
2012-11-22 8:50 ` Laurent Pinchart [this message]
2012-11-22 8:50 ` Laurent Pinchart
2012-11-22 8:50 ` Laurent Pinchart
2012-11-22 8:53 ` Sascha Hauer
2012-11-22 8:53 ` Sascha Hauer
2012-11-22 8:53 ` Sascha Hauer
[not found] ` <20121122085342.GB10369-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>
2012-11-22 9:07 ` Laurent Pinchart
2012-11-22 9:07 ` Laurent Pinchart
2012-11-22 9:07 ` Laurent Pinchart
2012-11-22 11:23 ` Steffen Trumtrar
2012-11-22 11:23 ` Steffen Trumtrar
2012-11-22 11:23 ` Steffen Trumtrar
2012-11-20 15:54 ` [PATCH v12 6/6] drm_modes: add of_videomode helpers Steffen Trumtrar
2012-11-20 15:54 ` Steffen Trumtrar
2012-11-20 15:54 ` Steffen Trumtrar
[not found] ` <1353426896-6045-7-git-send-email-s.trumtrar-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>
2012-11-21 12:52 ` Tomi Valkeinen
2012-11-21 12:52 ` Tomi Valkeinen
2012-11-21 12:52 ` Tomi Valkeinen
2012-11-20 16:13 ` [PATCH v12 0/6] of: add display helper Laurent Pinchart
2012-11-20 16:13 ` Laurent Pinchart
2012-11-20 18:11 ` Robert Schwebel
2012-11-20 18:11 ` Robert Schwebel
2012-11-20 19:35 ` Thierry Reding
2012-11-20 19:35 ` Thierry Reding
2012-11-21 8:28 ` Steffen Trumtrar
2012-11-21 8:28 ` Steffen Trumtrar
2012-11-21 13:18 ` Laurent Pinchart
2012-11-21 13:18 ` Laurent Pinchart
2012-11-21 7:41 ` Steffen Trumtrar
2012-11-21 7:41 ` Steffen Trumtrar
2012-11-21 7:41 ` Steffen Trumtrar
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