From mboxrd@z Thu Jan 1 00:00:00 1970 From: jacopo mondi Subject: Re: [RESEND PATCH v5 2/3] dt-bindings: display: atmel: optional video-interface of endpoints Date: Thu, 16 Aug 2018 21:46:51 +0200 Message-ID: <20180816194651.GA30122@w540> References: <20180803072308.14962-1-peda@axentia.se> <20180803072308.14962-3-peda@axentia.se> <20180803081128.GA4528@w540> <6fe3e84e-bd9d-0894-df8b-1b40c0f9477d@axentia.se> <20180803085143.GC4528@w540> <061a99d5-4fe6-795c-7e91-cf7127fb8472@axentia.se> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="x+6KMIRAuhnl3hBn" Return-path: Content-Disposition: inline In-Reply-To: <061a99d5-4fe6-795c-7e91-cf7127fb8472@axentia.se> Sender: linux-kernel-owner@vger.kernel.org To: Peter Rosin Cc: linux-kernel@vger.kernel.org, Boris Brezillon , David Airlie , Rob Herring , Mark Rutland , Nicolas Ferre , Alexandre Belloni , Laurent Pinchart , dri-devel@lists.freedesktop.org, devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Jyri Sarha , Daniel Vetter , Andrzej Hajda , Russell King - ARM Linux , Jacopo Mondi List-Id: devicetree@vger.kernel.org --x+6KMIRAuhnl3hBn Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Hi Peter, On Thu, Aug 16, 2018 at 02:52:41PM +0200, Peter Rosin wrote: > On 2018-08-03 10:51, jacopo mondi wrote: > > On Fri, Aug 03, 2018 at 10:40:02AM +0200, Peter Rosin wrote: > >> On 2018-08-03 10:11, jacopo mondi wrote: > >>> Hi Peter! > >>> > >>> On Fri, Aug 03, 2018 at 09:23:07AM +0200, Peter Rosin wrote: > >>>> With bus-type/bus-width properties in the endpoint nodes, the video- > >>>> interface of the connection can be specified for cases where the > >>>> heuristic fails to select the correct output mode. This can happen > >>>> e.g. if not all RGB pins are routed on the PCB; the driver has no > >>>> way of knowing this, and needs to be told explicitly. > >>>> > >>>> This is critical for the devices that have the "conflicting output > >>>> formats" issue (SAM9N12, SAM9X5, SAMA5D3), since the most significant > >>>> RGB bits move around depending on the selected output mode. For > >>>> devices that do not have the "conflicting output formats" issue > >>>> (SAMA5D2, SAMA5D4), this is completely irrelevant. > >>>> > >>>> Acked-by: Boris Brezillon > >>>> Reviewed-by: Rob Herring > >>>> Signed-off-by: Peter Rosin > >>>> --- > >>>> .../devicetree/bindings/display/atmel/hlcdc-dc.txt | 26 ++++++++++++++++++++++ > >>>> 1 file changed, 26 insertions(+) > >>>> > >>>> diff --git a/Documentation/devicetree/bindings/display/atmel/hlcdc-dc.txt b/Documentation/devicetree/bindings/display/atmel/hlcdc-dc.txt > >>>> index 82f2acb3d374..9de434a8f523 100644 > >>>> --- a/Documentation/devicetree/bindings/display/atmel/hlcdc-dc.txt > >>>> +++ b/Documentation/devicetree/bindings/display/atmel/hlcdc-dc.txt > >>>> @@ -15,6 +15,14 @@ Required children nodes: > >>>> to external devices using the OF graph reprensentation (see ../graph.txt). > >>>> At least one port node is required. > >>>> > >>>> +Optional properties in grandchild nodes: > >>>> + Any endpoint grandchild node may specify a desired video interface > >>>> + according to ../../media/video-interfaces.txt, specifically > >>>> + - bus-type: must be <0>. > >>> > >>> Is there any value in specifying this, if it has a fixed value to > >>> "autodetect"? I understand it's optional, so if nobody else objects, > >>> feels free to keep it there. > >> > >> That's just how media/video-interfaces.txt works. > >> > >> bus-type 0 means that other properties describe the bus type. In this > >> case bus-width is specified, so that means a parallel bus. But bus-width > >> has no meaning (or may not have) if bus-type is non-zero. But checking > >> that bus-type for zero in the code seemed like overkill to me since the > >> driver already knows that it is a parallel bus... > >> > > > > Yeah, I felt like pointing that out since you're not cheking for its value, > > and that property is only used by v4l2-fwnode to handle some > > not-that-used-anymore bus as CCP2 is. > > > >> TL;DR I'd like to keep it. > >> > > > > Fine with me then. > > > >>> > >>>> + - bus-width: recognized values are <12>, <16>, <18> and <24>, and > >>>> + override any output mode selection heuristic, forcing "rgb444", > >>>> + "rgb565", "rgb666" and "rgb888" respectively. > >>>> + > >>>> Example: > >>>> > >>>> hlcdc: hlcdc@f0030000 { > >>>> @@ -50,3 +58,21 @@ Example: > >>>> #pwm-cells = <3>; > >>>> }; > >>>> }; > >>>> + > >>> > >>> Two blank lines here. > >>> > >>>> + > >>>> +Example 2: With a video interface override to force rgb565; as above > >>>> +but with these changes/additions: > >>>> + > >>>> + &hlcdc { > >>>> + hlcdc-display-controller { > >>>> + pinctrl-names = "default"; > >>>> + pinctrl-0 = <&pinctrl_lcd_base &pinctrl_lcd_rgb565>; > >>>> + > >>>> + port@0 { > >>> > >>> The node has a unit address specified, you're missing a reg = <0> > >>> property (no big deal, it's an example, but the other one has it) > >>> > >>>> + hlcdc_panel_output: endpoint@0 { > >>> > >>> Missing reg here too. > >> > >> I'll fix those (I think they appeared for the original example after I > >> wrote the patch). > >> > > > > Ok, then please consider also describing the port@0 node cell sizes too > > since it has a child endpoint node. > > Ok, I have now figured out why this was as it were, and I no longer agree > with adding the extra properties. The whole of example 2 is inside a > reference (using the &hlcdc notation) to the hlcdc node in example 1, and > therefore these "missing" properties are not missing. I think they are > just clutter that hides what is really needed/different between example 1 > and 2, and apparently Boris and Rob agreed when they acked/reviewed. The > description of example 2 also clearly states that example 2 is changes > and additions on top of example 1. So, I plan to have this in the next > iteration: > > &hlcdc { > hlcdc-display-controller { > pinctrl-names = "default"; > pinctrl-0 = <&pinctrl_lcd_base &pinctrl_lcd_rgb565>; > > port@0 { > hlcdc_panel_output: endpoint@0 { > bus-width = <16>; Right, I thought that even when re-defining a node, reg properties should be there, but yes, I had no reasons to think so :) > }; > }; > }; > }; > > Jacopo, please let me know if you want me to keep your review tag anyway... > Sure > > >> Cheers, > >> Peter > >> > >>> Minors apart: > > ...because I interpret this to mean that I could add your tag if I made the > changes you suggested. Or did it mean that I could add your tag regardless > because the issues were minor? >v Sorry, I was not clear. That was a minor nit, you could have add my tag anyhow. Thanks j > Cheers, > Peter > > >>> > >>> Reviewed-by: Jacopo Mondi > >>> > >>> Thanks > >>> j > >>> > >>>> + bus-type = <0>; > >>>> + bus-width = <16>; > >>>> + }; > >>>> + }; > >>>> + }; > >>>> + }; > >>>> -- > >>>> 2.11.0 > >>>> > >> > --x+6KMIRAuhnl3hBn Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQIcBAEBAgAGBQJbddSlAAoJEHI0Bo8WoVY8+tMP/iDKNi5Ir9G8oN36J8pkC/xC wTC5GDuqwSNeL4SYh8gfIwn2rV4uJwPOCUZzHGXXnbVbNj7DDvQrd9QyHUVkLxJE NaSCkvWCOB5I5gYXH5yDPShs5KE3FH6ZIhpHCw+O0P9Evg40SA/AByaEIkfk99Ql fhwB6npxsYbvcxi0SO1hkJR3afu4dpTUpt5p4ixBHpzKA/XJUvJCMC+ScRNzNUEk haII2XPdvSmLMGHjPZF/iESWdMjZ+S1oJ73+MV5XFupwlWaDifwDgn4autva+aJ/ SZvKWGkDclXC8eWfwal11RITQkAp+M0rOaAuQePjpsbDEkDpGqjIPnclaToOyXdY RzpP7Cbms1VxIS36ycctnLGC48OTyizXHL/nd/ZdbufEyiIyprJG4P5TrPnvWNrB 7EIp2QlYpzMy5JSfV3bu7RQ27eiFrTTwIdSmjouaNMmBvzpVitRT8z89EoJsFmON xDS3q7BxvIN0p04usICCAJ2aBP3KVo3BW4N7rsEOOYL7wAg/vNsVL/9VkyXmE5ub dJZTrFftuB0tL/jixxnbIq6ris/kbK6pfahUfNvI/uOzpNQGcTgckK1m2R8mmEIB h4szakP+uQNkrMWzJNe86BKIVmkS9D2WJM51lG7Uok9XvaFxRBRQm5G2YDNk9uU6 9pmp1DfuMlgTVzY6TVfy =XDwT -----END PGP SIGNATURE----- --x+6KMIRAuhnl3hBn--