Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757132Ab3JKISD (ORCPT ); Fri, 11 Oct 2013 04:18:03 -0400 Received: from devils.ext.ti.com ([198.47.26.153]:52084 "EHLO devils.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756959Ab3JKIR7 (ORCPT ); Fri, 11 Oct 2013 04:17:59 -0400 Message-ID: <5257B420.10808@ti.com> Date: Fri, 11 Oct 2013 11:17:36 +0300 From: Tomi Valkeinen User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.0 MIME-Version: 1.0 To: "Dr. H. Nikolaus Schaller" , Lars-Peter Clausen CC: Marek Belisko , , , , Subject: Re: [PATCH] omapdss: Add new panel driver for Topolly td028ttec1 LCD. References: <1381352915-17219-1-git-send-email-marek@goldelico.com> <525662F5.3090600@ti.com> <7FAC77D4-5E1E-4B11-B067-3A8233C69240@goldelico.com> <52568B40.4040802@ti.com> <04AC7291-38E4-421B-979C-BF03D52E94BD@goldelico.com> <525699EF.6090803@ti.com> <52569CE8.5070201@metafoo.de> <5256F8DF.2020801@metafoo.de> <5257815F.5070803@ti.com> <5257A402.5030806@metafoo.de> <5570E6D7-4F66-40BE-A50C-6CCA8074BD83@goldelico.com> In-Reply-To: <5570E6D7-4F66-40BE-A50C-6CCA8074BD83@goldelico.com> X-Enigmail-Version: 1.5.2 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="3iHUkkh7XsED0U0cL1BRWplQIvKg3E0Wm" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3190 Lines: 79 --3iHUkkh7XsED0U0cL1BRWplQIvKg3E0Wm Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable On 11/10/13 10:42, Dr. H. Nikolaus Schaller wrote: > I am not sure if there is a SPI driver for a McBSP port [1]? And to mak= e that > work (reliably) and tested it might need a lot of work for us. At least= I think > such a change (e.g. setting up clock polarity etc.) is not done in some= minutes. > And the only feedback we have from the panel is "does not work"/"works"= =2E I.e. > if we are not lucky that it works immediately we have no real means to = debug. >=20 > IMHO it also gives more flexibility to board designers to choose GPIOs = instead > of enforcing some SPI interface by the driver (and encapsulate this arg= uable > protocol in the driver). Maybe some board has 3 spare GPIOs but neither= > McBSPs nor McSPIs available. This has been an interesting thread, I've learnt a lot =3D). I still think the panel driver should not handle this, but there should be a separate spi bitbang driver for it. I understand you're not enthusiastic going that way, as the current version works for you. However, when using DT, we need to think how to represent the hardware in the device tree data, and it has to be right from the beginning. That's why I won't allow representing this panel as having 4 gpios in the DT data, because that is not correct. The panel has 3 pins. But then, the panel does allow reading, which could be implemented using 4 gpios as you have done. This data should be in the spi-bitbang data, and the panel should just use the standard SPI framework. Using SPI framework does not mean you should use McBSP or McSPI. It's up to you how the 3-wire SPI is implemented on the SoC side, the panel would just work in all the cases. Tomi --3iHUkkh7XsED0U0cL1BRWplQIvKg3E0Wm Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.12 (GNU/Linux) Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ iQIcBAEBAgAGBQJSV7QgAAoJEPo9qoy8lh71aBQP/Rk3tQ+GsVBciDg+c3R6nkPf 5NR+rWAkYxOM8I9fi1FjThjeoQ4OQ/Av1xEApQR5+CgQx2GzlF6c4LFxwXsV97yN Rag9DqD/F+0esbRqQ7g0ZbEj3V12DKCT7X3Zoidch3p94XSYzzZGJr+ekQmff4L7 xUABb+SrfIdvS+DIjJ7ZmIUEoFulCkz0rU8av8Mu0WLkwCZorgpn2Tw7dh/p/YTw knKg5zg5EOvt7dA7jSXqZIWqniQxT0+NPWFdXfe1VCL+ypvFIotijTqG0MKo89vr C2nGnmTsMQCn9bI3+vS7f6csdT0ir0XgNRVTi6d/i1mr41eU4HCiMzj5H8Y4TTge uwG25nRFGRosOW3phfYx3v35bUvpenthhSBYibQO1PgIVemrioJwUWFCdeZ/ycpU unzARlR7r54MwVwq9SS+pSAYj7BcfXWGpuGj0Way0Sj/6Z21tMVhLtJ/+0Qb8Uz9 DjMKfWj3gR9wuA68skBm6pi4xb7lX+3R7s/UsIo3bIvOldmAFqX6Zk7UZVAY+ONm SgfmPNzAsKguymFmQ7FBPgv0YLd9VNVU4E8vTWw4mHlTvx7NwutzQ5uDSobPN+jM kBJo2Ck+E+eAv6flHkYD1xEmrxzYdVuq38r3ScYOrTFUH3JelxEkrgya4Q1gUwmj QIDcxOZivYX3P/L2vHP2 =w+kN -----END PGP SIGNATURE----- --3iHUkkh7XsED0U0cL1BRWplQIvKg3E0Wm-- -- 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/