From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752494AbcAFMPE (ORCPT ); Wed, 6 Jan 2016 07:15:04 -0500 Received: from mezzanine.sirena.org.uk ([106.187.55.193]:38192 "EHLO mezzanine.sirena.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752338AbcAFMPA (ORCPT ); Wed, 6 Jan 2016 07:15:00 -0500 Date: Wed, 6 Jan 2016 12:13:45 +0000 From: Mark Brown To: Khoa Dang Pham Cc: Jisheng Zhang , linux-spi@vger.kernel.org, linux-kernel@vger.kernel.org Message-ID: <20160106121345.GV6588@sirena.org.uk> References: <20151223192338.128e95a4@xhacker> <20151223121512.GV16023@sirena.org.uk> <20151223202952.28be5bab@xhacker> <20160105161231.GG6588@sirena.org.uk> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="FQ9/qgh0YgB02Feu" Content-Disposition: inline In-Reply-To: X-Cookie: APL hackers do it in the quad. User-Agent: Mutt/1.5.24 (2015-08-30) X-SA-Exim-Connect-IP: 94.175.94.161 X-SA-Exim-Mail-From: broonie@sirena.org.uk Subject: Re: [RFC] spi: dw: support setting tmode dynamically X-SA-Exim-Version: 4.2.1 (built Mon, 26 Dec 2011 16:24:06 +0000) X-SA-Exim-Scanned: Yes (on mezzanine.sirena.org.uk) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --FQ9/qgh0YgB02Feu Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Wed, Jan 06, 2016 at 08:45:38AM +0700, Khoa Dang Pham wrote: > Hi Mark, Please don't top post, reply in line with needed context. This allows readers to readily follow the flow of conversation and understand what you are talking about and also helps ensure that everything in the discussion is being addressed. > According to the "DesignWare DW_apb_ssi Databook" (version 3.21b) provided > by Synopsys, the EEPROM read is: > "When TMOD =3D 2=E2=80=98b11, the transmit data is used to transmit an op= code and/or > an address to the EEPROM > device. Typically this takes three data frames (8-bit opcode followed by > 8-bit upper address and 8-bit lower > address). During the transmission of the opcode and address, no data is > captured by the receive logic (as > long as the DW_apb_ssi master is transmitting data on its txd line, data = on > the rxd line is ignored). The This is just a normal data transfer, if the driver is functioning correctly this should not be required and requiring it would mean that we'd need to go round adding workarounds for this to lots of client drivers. It seems like you are trying to work around some other bug in the driver, quite possibly incorrect handling of chip select as was suggested elsewhere. If that is the case a common solution is to manage the chip select as a GPIO rather than with the built in handling in the block if the block can't cope. --FQ9/qgh0YgB02Feu Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQEcBAEBCAAGBQJWjQT4AAoJECTWi3JdVIfQseAH/RT/vje8QSfjrmrRIzfapofh 50oF5tIpa8yJPYu6XEM7SdWS5y3ok5x7MvmTyKMU8591Wd0LhgO/CO3wiA4HjnvH f918FC1VUOe4QI3QUbKncWLiicdpif/AISUIBrEyPz1caOr0FM1QQoDP+PJAZQ5L 8T14xu84EZ3Qnb4VFs+E2nfdRp448FC7GAYsL8/Q1ccESrGOfEWNKy5hLHTW284P qzDjxSj1tGYxKrNmX/8K3Jr62Ph/AH9e4tJB24QCPI7+4Zc53WrL6ufRLDRqEIb7 BMY5u4Ib7W3zpVbU1kI6Vym3pjU1vX33uES/LVYMOhnbXAif9Z50/Pfl9G1rocI= =A/aF -----END PGP SIGNATURE----- --FQ9/qgh0YgB02Feu--