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 761A6C433FE for ; Thu, 30 Sep 2021 13:07:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5C55E6126A for ; Thu, 30 Sep 2021 13:07:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1351360AbhI3NJK (ORCPT ); Thu, 30 Sep 2021 09:09:10 -0400 Received: from bhuna.collabora.co.uk ([46.235.227.227]:33686 "EHLO bhuna.collabora.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1351464AbhI3NIi (ORCPT ); Thu, 30 Sep 2021 09:08:38 -0400 Received: from [IPv6:2a02:810a:880:f54:fd5c:7cb1:aaa8:78b1] (unknown [IPv6:2a02:810a:880:f54:fd5c:7cb1:aaa8:78b1]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) (Authenticated sender: dafna) by bhuna.collabora.co.uk (Postfix) with ESMTPSA id 86ABE1F44D13; Thu, 30 Sep 2021 14:06:54 +0100 (BST) Subject: Re: [PATCH] Revert "spi: modify set_cs_timing parameter" To: Mark Brown Cc: kernel@collabora.com, linux-spi@vger.kernel.org, enric.balletbo@collabora.com, dafna3@gmail.com, Mason Zhang , Laxman Dewangan , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mediatek@lists.infradead.org, wsd_upstream@mediatek.com, Matthias Brugger References: <20210930120700.2564-1-dafna.hirschfeld@collabora.com> <20210930122513.GX4199@sirena.org.uk> <28f8af42-4535-ef9f-e521-712d37e2cb72@collabora.com> <20210930124630.GY4199@sirena.org.uk> From: Dafna Hirschfeld Message-ID: Date: Thu, 30 Sep 2021 15:06:52 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.13.0 MIME-Version: 1.0 In-Reply-To: <20210930124630.GY4199@sirena.org.uk> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 30.09.21 14:46, Mark Brown wrote: > On Thu, Sep 30, 2021 at 02:36:01PM +0200, Dafna Hirschfeld wrote: >> hi, thanks for the fast feedback >> >> On 30.09.21 14:25, Mark Brown wrote: >>> On Thu, Sep 30, 2021 at 02:07:00PM +0200, Dafna Hirschfeld wrote: >>>> This reverts commit 04e6bb0d6bb127bac929fb35edd2dd01613c9520. > >>> Which is not what the commit message nor the paste of the full hash >>> claimed :/ > >> What is the paste of the full hash? > > The above. > >> Since the second commit is only a warning fixes I thought it is cumbersome to >> send two separate reverting patches. Should I? > > No, you should write a proper commit log with (like I said) a normal > subject line - basically, follow the process in submitting-patches.rst. > >>> Do we have any analysis as to why? Do these devices use timing >>> parameters in some way for example, or do the values written out to the >>> device change in some way? > >>> You've provided no analysis here so it's hard to tell if this is just >>> some random change that happens to change code generation slighly or if >>> there's some actual reason why this might fix something. I'll note that >>> as far as I can see there are no users of this API upstream so I'm >>> guessing that you've got some out of tree consumer driver which uses the >>> API, it's possible that there was some error in updating that driver to >>> the new interface which is causing the issue. > >> Actually the original commit not only change that callback 'set_cs_timing' but it also >> calls 'mtk_spi_set_hw_cs_timing' directly from the function "mtk_spi_prepare_message". >> So this actually influences all devices bound to this driver (in upstream) >> I did some printing and it does change values that are written to registers. > > OK, so that's something that should have been in the commit log, > preferrably in a more detailed form that identifies what the change is. > However changing the values written out is clearly not the intent of the > patch and it is a substantially better API so can we not just fix things > so that the old values are written out? Why are we jumping straight to > a revert here? It could be that the values written to the register in the new version of "mtk_spi_set_hw_cs_timing" are the same as with the previous version. I didn't check that. The difference is that before that patch the function was not called so it was a dead code. Now it is called and causes erros. Without the datasheet it is hard to know how to fix it. I responded to that patch two days ago explaining that but Mason Zhang didn't respond yet. Thanks, Dafna >