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=-6.7 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS 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 9A7C1C4338F for ; Wed, 18 Aug 2021 10:10:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7BD3461053 for ; Wed, 18 Aug 2021 10:10:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233706AbhHRKLK (ORCPT ); Wed, 18 Aug 2021 06:11:10 -0400 Received: from mail.kernel.org ([198.145.29.99]:41750 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231218AbhHRKLG (ORCPT ); Wed, 18 Aug 2021 06:11:06 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 3357660524; Wed, 18 Aug 2021 10:10:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1629281432; bh=wtzJaNgezxfs0TQnqSoSUw27h/DL/OT0MGIc9e+X4pI=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=q6UvBf55t8CPKajq0+X6SO+xnWGNl4TcIWSz0YSf03rMO1S0eIUaJXE1qjH3IE0+Z 5t/YhHVZCGysC8PnT0YNX1mmSKzV8YbAf3xfBT6wET0IGSWA1hQAtUOoX/bIvkmgPJ 29PIYLB9IVGyelebgAVPUpHWN16SS9ZXMmMG3oLP6GMz95GGz1+7cYwoDvbR9qQtE4 jQkY9lUUNVWdqw79/si7mVWkPsPD2Q5VbaaH8wAYMdHbVtwz8PCv69rBLIoymswL1f xcsXLgIuBFmaqjnwDuR4wxKP8uzbsQZn4kF7Cc0Yp2XWmexxJuGe7jc72yLCaoZ439 N7/UpvLD+SNYw== Date: Wed, 18 Aug 2021 15:40:27 +0530 From: Vinod Koul To: Mauro Carvalho Chehab Cc: Bjorn Helgaas , linuxarm@huawei.com, mauro.chehab@huawei.com, Greg Kroah-Hartman , Kishon Vijay Abraham I , Manivannan Sadhasivam , Rob Herring , linux-kernel@vger.kernel.org, linux-phy@lists.infradead.org Subject: Re: [PATCH v11 01/11] phy: HiSilicon: Add driver for Kirin 970 PCIe PHY Message-ID: References: <7788c5ead6d6f5a6f9e5faaee4460eb2149967c4.1628755058.git.mchehab+huawei@kernel.org> <20210818110123.33eba838@coco.lan> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210818110123.33eba838@coco.lan> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 18-08-21, 11:01, Mauro Carvalho Chehab wrote: > Hi Vinod, > > Em Tue, 17 Aug 2021 16:12:37 +0530 > Vinod Koul escreveu: > > > > + /* FIXME: calling it causes an Asynchronous SError interrupt */ > > > +// kirin_pcie_clk_ctrl(phy, false); > > > > when will you fix the fixme and pls remove the deadcode > > Working with clocks on this SoC is very tricky: there are lots of clock > lines (~70) that are critical for this device to work. Such lines are > enabled via the Device's firmware, and are supposed to be always > powered. Powering off such clock lines cause a SError. > > Most clocks on this device are managed by the clk-hikey3670 driver. > At the current state of clk-hi3670, the only way for HiKey 970 > to even boot is to add: > > clk_ignore_unused=true > > as a Kernel boot parameter. That is the solution given by the downstream > official distributions for HiKey970 at 96boards. > > The fix is to flag the critical clocks with CLK_IS_CRITICAL at the > clk-hi3670 driver, but finding the right clock set has been a challenge. > > I spent the last couple of weeks trying to identify the critical ones, > as I'm aiming to be able to use a Kernel built with a default arm64 > one of my goals is to have this device working fine with a > "make defconfig" Kernel. > > So, I added this patch: > > https://lore.kernel.org/lkml/2d2de5e902ced072bcfd5e5311d6b10326b9245b.1627041240.git.mchehab+huawei@kernel.org/ > > to my tree (which reduces the set of clocks using CLK_IGNORE_UNUSED > from 308 to 163 clocks). Than I ran script that was dropping the > flag one by one, boots the new Kernel and do a sanity check. When it > fails to boot, I manually dropped the patch, and re-run the script > to test the remaining clocks. After a couple of weeks, I reached a patch > with 78 clock lines that seemed critical, but the resulting patch was > not stable, as, depending on the day I boot the Kernel with such patch, > it crashes with SError in a couple of seconds after booting, or > cause the Ethernet firmware to not load. > > I intend to keep trying to find the clock lines that can't be disabled, > but this is very time consuming, as I couldn't find any documentation > about that. So, it has to be done empirically. > > - > > In any case, fixing it doesn't sound a critical issue for the PHY > driver. I mean, right now, this patchset allows removing and > re-inseting the PCIe driver, which is already an improvement over the > original upstream driver, which was missing the power-off logic for > Kirin 960. > > With this patchset, both power-off/power-on logic for both HiKey960 > (where the PHY is inside the pcie-kirin driver) and for HiKey970, > which uses this PHY driver. On both devices, I tested an endless loop > with rmmod/modprobe for the PCIe. > > Besides that, in practice, removing PCIe in runtime is something that > people usually don't do. > > So, while it would be cool to balance the clock disable logic, > I don't think this is a critical issue in this particular case. Okay sounds fair to me, I think fixme should be left but the c99 style code commented out can be removed -- ~Vinod