From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 17F17C74A35 for ; Thu, 11 Jul 2019 14:42:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E0B3820872 for ; Thu, 11 Jul 2019 14:42:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1562856131; bh=aCgXeqJ8mNWJ4/2022RlpqZ1yK0g76+pWdfTQmLtDck=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=hkuwnxLuh2jgPdl7nPDyWS+BFJrI566Dy2kPPejqDRptRCDa2+A0aQgbRtwaDehKI Ea6gA01ILfwfAnWo73ySWDnYK5qLJxeX5kEbe1o8BBqPxS7DS/+aoB4cIF9D7M6BJu JgfrjpgDwBxY5uZkbkkbkKsec0zkZseTmcODojH4= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728517AbfGKOmK (ORCPT ); Thu, 11 Jul 2019 10:42:10 -0400 Received: from heliosphere.sirena.org.uk ([172.104.155.198]:51056 "EHLO heliosphere.sirena.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728678AbfGKOmK (ORCPT ); Thu, 11 Jul 2019 10:42:10 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=sirena.org.uk; s=20170815-heliosphere; h=In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=+HlbWEQmRduQNmwZFRzhfjm5S2Nl7jUTbuTLfBpBQqk=; b=Wou5o/MPpOc6TgukRzTBE/GH+ RjTTLTQbUoZs3rqtFDNYiTTqcywlE97WS1aQvfu0aZSweV6wT+FTGnPpwgRC7hPVC1T1yktQXgFF0 y4n54l2AWJtFqwvW014NATDZc/TT5iZI6BS4La50RlA2uClTaigHVREvsuAgme/SIif/I=; Received: from [217.140.106.52] (helo=fitzroy.sirena.org.uk) by heliosphere.sirena.org.uk with esmtpsa (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1hlaGm-0002Ug-9P; Thu, 11 Jul 2019 14:42:00 +0000 Received: by fitzroy.sirena.org.uk (Postfix, from userid 1000) id 7990FD02DA8; Thu, 11 Jul 2019 15:41:59 +0100 (BST) Date: Thu, 11 Jul 2019 15:41:59 +0100 From: Mark Brown To: Jeffrey Hugo Cc: Andrzej Hajda , Laurent Pinchart , Dave Airlie , Daniel Vetter , Rob Clark , Bjorn Andersson , "open list:DRM PANEL DRIVERS" , MSM , lkml Subject: Re: [PATCH 1/2] regmap: Add DSI bus support Message-ID: <20190711144159.GH14859@sirena.co.uk> References: <20190703214326.41269-1-jeffrey.l.hugo@gmail.com> <20190703214512.41319-1-jeffrey.l.hugo@gmail.com> <20190706010604.GG20625@sirena.org.uk> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="aF3LVLvitz/VQU3c" Content-Disposition: inline In-Reply-To: X-Cookie: Visit beautiful Vergas, Minnesota. User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-arm-msm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-arm-msm@vger.kernel.org --aF3LVLvitz/VQU3c Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Wed, Jul 10, 2019 at 12:08:34PM -0600, Jeffrey Hugo wrote: > On Fri, Jul 5, 2019 at 7:06 PM Mark Brown wrote: > The addresses for these spec defined messages are 8-bit wide, so 256 > valid "destinations". However, the payload is variable. Most of the > defined operations take an 8-bit payload, but there are a few that I > see with 16-bit payloads. Oh, good, variable register sizes, what a market leading idea :( That basically doesn't work with regmap, you need to either define one regmap per register size and attach them to the device or use reg_read() and reg_write() and hide the complexity in there. > As the contents of the generic read/write messages are implementation > defined, the answer to your question seems to be no - the spec does > not define that the registers are 8-bit addressable, and 8-bit wide. The code definitely ought to at least be more flexible then. Right now it's very hard coded. > I think perhaps the discussion needs to step back a bit, and decide > how flexible do we want this regmap over DSI to be? I think its > usefulness comes from when a device can be configured via multiple > interfaces, so I don't expect it to be useful for every DSI interface. > It seems like the DSI panels use DSI directly to craft their > configuration. As a result, we are probably looking at just devices > which use the generic read/write commands, but sadly the format for > those is not universal per the spec. From the implementations I've > seen, I suspect 8-bit addressing of 8-bit wide registers to be the > most common, but apparently there is an exception to that already in > the one device that I care about. It's relatively easy to add a bunch of special cases in - look at how the I2C code handles it, keying off a combination of the register configuration and the capabilities of the host controller. I guess for this it'd mainly be the register configuration. You might find the reg_read()/reg_write() interface better than the raw buffer one for some of the formats, it does let=20 > Do we want to go forward with this regmap support just for the one TI > device, and see what other usecases come out of it, and attempt to > solve those as we go? I have no strong opinions here, it looks fine from a framework point of view though it's unclear to me if viewing it as a register map meshes well with how the hardware is designed or not - it seems plausible though. --aF3LVLvitz/VQU3c Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAABCgAdFiEEreZoqmdXGLWf4p/qJNaLcl1Uh9AFAl0nSrQACgkQJNaLcl1U h9Dqygf/XOpd88JPRHZWBN+yYZ3UHJfhBe6xy8/HfJBBT8sXXA2L3k7rHpRMmhKk RC58a6kuy8mDm+tQhIgEwHUlFotAHGk8kn0yNQuVK0XNL4zvAqdcQHV+gsn//x6G R3PQrLboonlT69lWDNW4dI1zc78mY6FzKQRtFa7kmIYZ5hr/WwtR9TfpReeUxLCr P5FYi4QzBp3uloWecgLExYmFZj3IHznUWpp8Hm11JDXyrpVShOMJCiA99q/W9N6A ALxrijQlTenDH7gMw7YEaDhnl+osCa392CguDJiSNbDW7usZ+5WGOF7TGOLu8F+u udGDeMVl9eOc7g2CHoRTEg6/WtQv/A== =1lgs -----END PGP SIGNATURE----- --aF3LVLvitz/VQU3c--