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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id DA6C2C433EF for ; Mon, 8 Nov 2021 18:53:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C3A15617E4 for ; Mon, 8 Nov 2021 18:53:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236237AbhKHS43 convert rfc822-to-8bit (ORCPT ); Mon, 8 Nov 2021 13:56:29 -0500 Received: from aposti.net ([89.234.176.197]:33428 "EHLO aposti.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236093AbhKHS42 (ORCPT ); Mon, 8 Nov 2021 13:56:28 -0500 Date: Mon, 08 Nov 2021 18:53:24 +0000 From: Paul Cercueil Subject: Re: [PATCH v5 2/7] drm/ingenic: Add support for JZ4780 and HDMI output To: "H. Nikolaus Schaller" Cc: Rob Herring , Mark Rutland , Thomas Bogendoerfer , Geert Uytterhoeven , Kees Cook , "Eric W. Biederman" , Miquel Raynal , David Airlie , Daniel Vetter , Neil Armstrong , Robert Foss , Laurent Pinchart , Jernej Skrabec , Harry Wentland , Sam Ravnborg , Maxime Ripard , Hans Verkuil , Liam Girdwood , Mark Brown , Paul Boddie , OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS , linux-mips , linux-kernel , Discussions about the Letux Kernel , Jonas Karlman , dri-devel Message-Id: <0HO92R.RF221XL59J3I1@crapouillou.net> In-Reply-To: References: <2c7d0aa7d3ef480ebb996d37c27cbaa6f722728b.1633436959.git.hns@goldelico.com> <7CEBB741-2218-40A7-9800-B3A154895274@goldelico.com> <229EBE4C-6555-41DE-962F-D82798AEC650@goldelico.com> <2E32F572-72D0-44E7-A700-AF8A2D37BFDA@goldelico.com> <2F8A88BC-2696-491B-9C01-7D07A3B3670A@goldelico.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1; format=flowed Content-Transfer-Encoding: 8BIT Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Nikolaus, Le lun., nov. 8 2021 at 19:33:48 +0100, H. Nikolaus Schaller a écrit : > Hi Paul, > >> Am 08.11.2021 um 18:49 schrieb Paul Cercueil : >> >>>> Variant 4: the variant #2 without the changes to the DTSI files. >>> Hm. If there is no cache and we can safely remove tight boundary >>> checking (by JZ_REG_LCD_SIZE1) for jz4725/40/70 (by not fixing >>> DTSI) why do we still need the max_register calculation from DTSI >>> specifically for jz4780 and at all? >> >> It's better to have the .max_register actually set to the proper >> value. Then reading the registers from debugfs >> (/sys/kernel/debug/regmap/) will print the actual list of registers >> without bogus values. If .max_register is set too high, it will end >> up reading outside the registers area. > > Ok, that is a good reason to convince me. > >> On Ingenic SoCs such reads just return 0, but on some other SoCs it >> can lock up the system. > > Yes, I know some of these... > >> So the best way forward is to have .max_register computed from the >> register area's size, and fix the DTSI with the proper sizes. Since >> your JZ4780 code needs to update .max_register anyway it's a good >> moment to add this patch, and the DTSI files can be fixed later (by >> me or whoever is up to the task). > > Well, it would already be part of my Variant #2 (untested). So I > could simply split it up further and you can test the pure dtsi > changes and apply them later or modify if that makes problems. Saves > you a little work. BTW: the jz4740 seems to have even less registers > (last register seems to be LCDCMD1 @ 0x1305005C). Sure, if you want. Send the DTSI patch(es) separate from this patchset then. >> >> Fixing the DTS is not a problem in any way, btw. We just need to >> ensure that the drivers still work with old DTB files, which will be >> the case here. > > Yes, that is right since the new values are smaller than the > originals. > > Ok, then let's do it that way. Great. Waiting for your v6 then. Cheers, -Paul