From mboxrd@z Thu Jan 1 00:00:00 1970 From: Laurent Pinchart Subject: Re: [PATCH/RFC v3 08/19] video: display: Add MIPI DBI bus support Date: Fri, 06 Sep 2013 16:09:13 +0200 Message-ID: <9919519.TaAubJ8jzD@avalon> References: <1376068510-30363-1-git-send-email-laurent.pinchart+renesas@ideasonboard.com> <1376068510-30363-9-git-send-email-laurent.pinchart+renesas@ideasonboard.com> <521B37BA.50706@ti.com> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============0484118976==" Return-path: Received: from perceval.ideasonboard.com (perceval.ideasonboard.com [95.142.166.194]) by gabe.freedesktop.org (Postfix) with ESMTP id C600DE5E08 for ; Fri, 6 Sep 2013 07:09:20 -0700 (PDT) In-Reply-To: <521B37BA.50706@ti.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dri-devel-bounces+sf-dri-devel=m.gmane.org@lists.freedesktop.org Errors-To: dri-devel-bounces+sf-dri-devel=m.gmane.org@lists.freedesktop.org To: Tomi Valkeinen Cc: linux-fbdev@vger.kernel.org, dri-devel@lists.freedesktop.org, Jesse Barnes , Benjamin Gaignard , Laurent Pinchart , Tom Gall , Kyungmin Park , linux-media@vger.kernel.org, Stephen Warren , Mark Zhang , Alexandre Courbot , Ragesh Radhakrishnan , Thomas Petazzoni , Sunil Joshi , Maxime Ripard , Vikas Sajjan , Marcus Lorentzon List-Id: dri-devel@lists.freedesktop.org --===============0484118976== Content-Type: multipart/signed; boundary="nextPart3592204.0tyTd2Rpls"; micalg="pgp-sha1"; protocol="application/pgp-signature" --nextPart3592204.0tyTd2Rpls Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" Hi Tomi, On Monday 26 August 2013 14:10:50 Tomi Valkeinen wrote: > On 09/08/13 20:14, Laurent Pinchart wrote: > > MIPI DBI is a configurable-width parallel display bus that transmits > > commands and data. > > > > Add a new DBI Linux bus type that implements the usual bus > > infrastructure (including devices and drivers (un)registration and > > matching, and bus configuration and access functions). > > This has been discussed before, but I don't remember that the issue would > have been cleared, so I'm bringing it up again. > > What benefit does a real Linux DBI (or DSI) bus give us, compared to > representing the DBI the same way as DPI? DBI & DSI are in practice point- > to-point buses, and they do not support probing. Is it just that because DBI > and DSI can be used to control a device, they have to be Linux buses? The idea was to reuse the Linux bus infrastructure to benefit from features such as power management. Implementing DBI/DSI control functions using a DBI/DSI bus is also pretty easy, and would allow controlling DBI/DSI entities much like we control I2C entities. I don't like the idea of using an I2C bus with I2C access functions on one side, and embedding the DBI/DSI access functions as part of CDF entity operations on the other side very much. This being said, this isn't the part of CDF that matters the most to me (it's actually not part of CDF strictly speaking). If your model works well enough it won't be too hard to convince me :-) > How do you see handling the devices where DBI or DSI is used for video only, > and the control is handled via, say, i2c? The module has to register two > drivers, and try to keep those in sync? I feel that could get rather hacky. If DBI or DSI is used for video only you don't need DBI/DSI control operations, right ? So the entity driver will just be a regular I2C device driver. > A real Linux bus would be necessary if we had devices that used DBI or DSI > only for control, and some other video bus for video data. But that sounds > so silly that I think we can just forget about the case. I certainly hope so :-) > Thus DBI and DSI are used either for video only, or video and control. -- Regards, Laurent Pinchart --nextPart3592204.0tyTd2Rpls Content-Type: application/pgp-signature; name="signature.asc" Content-Description: This is a digitally signed message part. Content-Transfer-Encoding: 7Bit -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.20 (GNU/Linux) iQEcBAABAgAGBQJSKeITAAoJEIkPb2GL7hl1AosIAKaIlwFLMvEqBxLhJTgYHfVX 8gqb9puzkQ5ZlOahTQ+UlcbVRHKI3uJrUScZ33FTk/ckKc1oPEDksMH8osOEepXD oTa3QcLlVv43YChzxh51qlKSNIjBXcI3M6lg5TW+wgTbniSS6pgw/dm8ZVBK9PgX Uc4b/m6abfbuxAlWJ2Kb1Z9+tmaccrp8CJCt585s14x9LnxgoSFxZAPewc3l1Tcg yPJb85UvUMGGdkTaAnoqq9Oj4zB16Te6jDOhORIxu28BDMNbb6auuzHSh8TXUEGO RQ+FLHz8qG0JG3pgoXV6maQddeV7ZskwYp8D4lymuPn9O1ahvvr+xo26HJEJH1g= =e0ei -----END PGP SIGNATURE----- --nextPart3592204.0tyTd2Rpls-- --===============0484118976== Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/dri-devel --===============0484118976==--