From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tomi Valkeinen Subject: Re: [PATCH V7 11/12] Documentation: bridge: Add documentation for ps8622 DT properties Date: Fri, 19 Sep 2014 17:28:37 +0300 Message-ID: <541C3D95.7080200@ti.com> References: <1409150399-12534-1-git-send-email-ajaykumar.rs@samsung.com> <5419760A.7020908@ti.com> <5419B52D.4060107@ti.com> <541C279A.2030601@ti.com> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="GO1Cened6e0kAPP7GqNKoDFnnKqw892jc" Return-path: In-Reply-To: Sender: linux-samsung-soc-owner@vger.kernel.org To: Ajay kumar Cc: Ajay Kumar , InKi Dae , "dri-devel@lists.freedesktop.org" , "linux-samsung-soc@vger.kernel.org" , "devicetree@vger.kernel.org" , Thierry Reding , Rob Clark , Daniel Vetter , Sean Paul , Jingoo Han , sunil joshi , Prashanth G , Laurent Pinchart List-Id: devicetree@vger.kernel.org --GO1Cened6e0kAPP7GqNKoDFnnKqw892jc Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable On 19/09/14 16:59, Ajay kumar wrote: > I am not really able to understand, what's stopping us from using this > bridge on a board with "complex" display connections. To use ps8622 dri= ver, > one needs to "attach" it to the DRM framework. For this, the DRM driver= Remember that when we talk about DT bindings, there's no such thing as DRM. We talk about hardware. The same bindings need to work on any operating system. > would need the DT node for ps8622 bridge. For which I use a phandle. A complex one could be for example a case where you have two different panels connected to ps8622, and you can switch between the two panels with, say, a gpio. How do you present that with a simple phandle? In the exynos5420-peach-pit.dts, which you linked earlier, I see a "panel" property in the ps8625 node. That's missing from the bindings in this patch. Why is that? How is the panel linked in this version? > If some XYZ platform wishes to pick the DT node via a different method,= > they are always welcome to do it. Just because I am not specifying a > video port/endpoint in the DT binding example, would it mean that platf= orm > cannot make use of ports in future? If that is the case, I can add some= thing All the platforms share the same bindings for ps8622. If you now specify that ps8622 bindings use a simple phandle, then anyone who uses ps8622 should support that. Of course the bindings can be extended in the future. In that case the drivers need to support both the old and the new bindings, which is always a hassle. Generally speaking, I sense that we have different views of how display devices and drivers are structured. You say "If some XYZ platform wishes to pick the DT node via a different method, they are always welcome to do it.". This sounds to me that you see the connections between display devices as something handled by a platform specific driver. I, on the other hand, see connections between display devices as common properties. Say, we could have a display board, with a panel and an encoder and maybe some other components, which takes parallel RGB as input. The same display board could as well be connected to an OMAP board or to an Exynos board. I think the exact same display-board.dtsi file, which describes the devices and connections in the display board, should be usable on both OMAP and Exynos platforms. This means we need to have a common way to describe video devices, just as we have for other things. Tomi --GO1Cened6e0kAPP7GqNKoDFnnKqw892jc Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQIcBAEBAgAGBQJUHD2VAAoJEPo9qoy8lh71u3cP/0lj+cMaortF7yLJHA9dlpiu h/3xLFrkIe8yutuuA93HnKNDc4Fkb7HTzEn4+tRZ3n5HzbnGiaR6WZcjGswIp0HT u9VC4FJ8o8RMjS/p7SeGJXhW16jQ+hjC1XAiqHOA6HdQA2ldtuuID8lbcoX51x2P MSeF/Lk9CBlAVynPGQqxScbYWUd7eegoQKcig74GYV+dHeUokWgtFzGqJ1I12/fO KSHRgJQUyD/V3j20z7Br3YlhZXdBvTlvaUN0bbZ7Y9sGFpb0MreL1GpTpFKWWy6S QXCT+OR+CaWybqttJhgTkTFkGOO8YTDgxE1NJCHWRXX3y23HUU49TRW+8PZ8nbSe sTJWTZBhLhTjIwQNHAupSI/0wYX9AfJZKzQk8JlGCpLuTRhqBqjOQull+1qj8Xyg FDn+L34JXxqgLskZPS1qd57h6OF1c0U6LJSe8RdITOCN8pdj0mgRn37AdExhlkmx 0kBXjHpRtz5Opi4e1iaK55QLfswgZZZ54zBITsfYDp9TwSzlMFba1zQuq/nOsmin W24f+K1hmv5MSvAREPtS1Uhm6UKG2zdvPym5wjFWN9to/PFhJy8N2LciS4q378JM zl3tiFlunRooLvDx9KuNJbn3aRrBg8jZ7igo4++lfjX7OrYl/p60+LgGBkGaQi5A ILdntIc5Orda9agLJsZR =m4x5 -----END PGP SIGNATURE----- --GO1Cened6e0kAPP7GqNKoDFnnKqw892jc--