Re: [PATCH v2 2/3] drm/panel: add support for EDT panels

From: Philipp Zabel <p.zabel@pengutronix.de>
To: Thierry Reding <thierry.reding@gmail.com>
Cc: stefan@agner.ch, swarren@wwwdotorg.org, linux@arm.linux.org.uk,
	devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, linux-tegra@vger.kernel.org,
	marcel@ziswiler.com
Subject: Re: [PATCH v2 2/3] drm/panel: add support for EDT panels
Date: Thu, 15 May 2014 11:30:29 +0200	[thread overview]
Message-ID: <1400146229.4102.26.camel@paszta.hi.pengutronix.de> (raw)
In-Reply-To: <20140515090814.GB6434@ulmo>

Am Donnerstag, den 15.05.2014, 11:08 +0200 schrieb Thierry Reding:
> On Thu, May 15, 2014 at 10:27:29AM +0200, Philipp Zabel wrote:
> > Am Donnerstag, den 15.05.2014, 09:51 +0200 schrieb Thierry Reding:
> > > On Wed, May 14, 2014 at 11:45:57PM +0200, stefan@agner.ch wrote:
> > > > From: Stefan Agner <stefan@agner.ch>
> > > > 
> > > > This panels are sold by Toradex for Colibri T20/T30 and Apalis T30
> > > > evaluation kits.
> > > > 
> > > > Signed-off-by: Stefan Agner <stefan@agner.ch>
> > > 
> > > Panel patches should go to the dri-devel mailing list as well.
> > > 
> > > Also a patch was posted only yesterday for a panel that seems to be the
> > > exact same one as this, even though the name differs minimally, see:
> > > 
> > > 	https://patchwork.kernel.org/patch/4175251/
> > > 
> > > Adding Philipp on Cc so you guys can work together whether this is
> > > indeed the same panel. The only differences seem to be in the vertical
> > > front and back porches, but I suspect that either settings will work on
> > > both Tegra and i.MX.
> > 
> > The ETM0700G0DH6 Datasheet lists 2 lines as the typical vsync pulse
> > width, 525 lines as the vertical period, and 35 lines as the vsync -de
> > time, which is vsync len + back porch.
> > So vertical timings 480 + 10 + 2 + 33 = 525 should be valid for the
> > ET0700G0DH6 panel:
> 
> Shouldn't that work with 480 + 8 + 2 + 35 too? It seems to me that it
> should still be safe for that panel. Similarily I'd expect your timings
> to work on the ET070080DH6.
>
> Irrespective of that they both seem to have different capabilities so
> two compatible values should be fine. However for the purpose of the
> simple panel driver they could be made to share the same timings if it
> works for both panels and devices.

Yes. As I understand, the 480 + 10 + 2 + 33 timing should be correct for
both panels.

> As for the touch panel on the ETM0700G0DH6, do you happen to know how
> that's usually connected? I suspect it needs external hardware to
> capture the YU, XL, YD and XR pins and turn that into raw coordinates
> and pen down interrupts.

The ETM0700G0DH6 has a capacitive touch screen with an EDT-FT5406
controller connected via I2C, at least on the panels that I have seen.

regards
Philipp