Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755299AbaAUSR6 (ORCPT ); Tue, 21 Jan 2014 13:17:58 -0500 Received: from mail-qc0-f180.google.com ([209.85.216.180]:48042 "EHLO mail-qc0-f180.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755125AbaAUSR5 (ORCPT ); Tue, 21 Jan 2014 13:17:57 -0500 MIME-Version: 1.0 X-Originating-IP: [173.13.129.225] In-Reply-To: <20140120105410.15705f32@armhf> References: <20140119195844.0c975b90@armhf> <20140120105410.15705f32@armhf> Date: Tue, 21 Jan 2014 10:17:56 -0800 Message-ID: Subject: Re: [PATCH v3 16/24] drm/i2c: tda998x: add DT documentation From: Olof Johansson To: Jean-Francois Moine Cc: Russell King - ARM Linux , "linux-kernel@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "devicetree@vger.kernel.org" Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jan 20, 2014 at 1:54 AM, Jean-Francois Moine wrote: > On Sun, 19 Jan 2014 20:06:09 -0800 > Olof Johansson wrote: > >> Hi, >> >> On Sun, Jan 19, 2014 at 10:58 AM, Jean-Francois Moine wrote: >> > Signed-off-by: Jean-Francois Moine >> > --- >> > .../devicetree/bindings/drm/i2c/tda998x.txt | 24 ++++++++++++++++++++++ >> > 1 file changed, 24 insertions(+) >> > create mode 100644 Documentation/devicetree/bindings/drm/i2c/tda998x.txt >> >> Please cc bindings for review to devicetree@vger.kernel.org (cc:d here now) >> >> > diff --git a/Documentation/devicetree/bindings/drm/i2c/tda998x.txt b/Documentation/devicetree/bindings/drm/i2c/tda998x.txt >> > new file mode 100644 >> > index 0000000..72da71d >> > --- /dev/null >> > +++ b/Documentation/devicetree/bindings/drm/i2c/tda998x.txt >> > @@ -0,0 +1,24 @@ >> > +Device-Tree bindings for the NXP TDA998x HDMI transmitter >> > + >> > +Required properties; >> > + - compatible: must be "nxp,tda998x" >> > + >> > +Optional properties: >> > + - interrupts: interrupt number for HDMI exchanges - default: by polling >> >> What are HDMI exchanges, and how do they differ from other interrupts? > > The used HDMI interrupt events are screen plug/unplug and EDID read. > There are also CEC read/write which are not yet implemented in the > tda998x driver. > > There is no difference from normal interrupts, except that the events > may be get by polling, so, the interrupt number is optional.] Ok, then it looks like the property description is a little confusing. I'd remove the mentioning of HDMI exchanges from it. >> > + >> > + - pinctrl-0: pin control group to be used for this controller (IRQ). >> > + >> > + - pinctrl-names: must contain a "default" entry. >> > + >> > + - video-ports: 24 bits value - default: <0x230145> >> >> What is this? > > The video-ports value defines how the video controller is connected to > the tda998x chip. Each 4 bits value tells from which input pins comes > the video data and if there is any bit inversion. Each byte of this > video-ports is used to load the VIP_CNTRL_{0,1,2} registers. These ones > are described in the TDA9983B documentation which is the closer > available document about the TDA998x family. > > The default value is the one defined for TI boards. > A known other value is <0x234501> which is used for Russell's Armada > DRM driver in the Cubox (Marvell A510), but this driver has no DT > support. Ok, this is a classic case where the binding should describe how things are configured/wired up instead of hardcoding a register value like this. From the data sheet there seems to be a _lot_ of settings, so selecting the needed subset for now might be acceptable (and go with defaults on the rest). -Olof -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/