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=-7.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=ham 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 C397BC282DD for ; Thu, 9 Jan 2020 13:29:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 97F7F20661 for ; Thu, 9 Jan 2020 13:29:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731135AbgAIN3n (ORCPT ); Thu, 9 Jan 2020 08:29:43 -0500 Received: from foss.arm.com ([217.140.110.172]:59056 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731054AbgAIN3n (ORCPT ); Thu, 9 Jan 2020 08:29:43 -0500 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 6179E31B; Thu, 9 Jan 2020 05:29:42 -0800 (PST) Received: from arm.com (e112269-lin.cambridge.arm.com [10.1.194.52]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 65F263F534; Thu, 9 Jan 2020 05:29:40 -0800 (PST) Date: Thu, 9 Jan 2020 13:29:35 +0000 From: Steven Price To: Robin Murphy Cc: Nicolas Boichat , Rob Herring , Mark Rutland , "devicetree@vger.kernel.org" , Tomeu Vizoso , David Airlie , "linux-kernel@vger.kernel.org" , "dri-devel@lists.freedesktop.org" , Liam Girdwood , Mark Brown , "linux-mediatek@lists.infradead.org" , Alyssa Rosenzweig , "hsinyi@chromium.org" , Matthias Brugger , "linux-arm-kernel@lists.infradead.org" Subject: Re: [PATCH v2 0/7] Add dts for mt8183 GPU (and misc panfrost patches) Message-ID: <20200109132934.GA6198@arm.com> References: <20200108052337.65916-1-drinkcat@chromium.org> <79fe7055-c11b-c9f6-64e5-48e3d5687dfe@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Sender: devicetree-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org On Thu, Jan 09, 2020 at 01:10:33PM +0000, Robin Murphy wrote: > On 09/01/2020 12:01 pm, Steven Price wrote: > > On 08/01/2020 05:23, Nicolas Boichat wrote: > >> Hi! > >> > >> Sorry for the long delay since > >> https://patchwork.kernel.org/patch/11132381/, > >> finally got around to give this a real try. > >> > >> The main purpose of this series is to upstream the dts change and the > >> binding > >> document, but I wanted to see how far I could probe the GPU, to check > >> that the > >> binding is indeed correct. The rest of the patches are > >> RFC/work-in-progress, but > >> I think some of them could already be picked up. > >> > >> So this is tested on MT8183 with a chromeos-4.19 kernel, and a ton of > >> backports to get the latest panfrost driver (I should probably try on > >> linux-next at some point but this was the path of least resistance). > >> > >> I tested it as a module as it's more challenging (originally probing > >> would > >> work built-in, on boot, but not as a module, as I didn't have the power > >> domain changes, and all power domains are on by default during boot). > >> > >> Probing logs looks like this, currently: > >> [  221.867726] panfrost 13040000.gpu: clock rate = 511999970 > >> [  221.867929] panfrost 13040000.gpu: Linked as a consumer to > >> regulator.14 > >> [  221.868600] panfrost 13040000.gpu: Linked as a consumer to > >> regulator.31 > >> [  221.870586] panfrost 13040000.gpu: Linked as a consumer to > >> genpd:0:13040000.gpu > >> [  221.871492] panfrost 13040000.gpu: Linked as a consumer to > >> genpd:1:13040000.gpu > >> [  221.871866] panfrost 13040000.gpu: Linked as a consumer to > >> genpd:2:13040000.gpu > >> [  221.872427] panfrost 13040000.gpu: mali-g72 id 0x6221 major 0x0 > >> minor 0x3 status 0x0 > >> [  221.872439] panfrost 13040000.gpu: features: 00000000,13de77ff, > >> issues: 00000000,00000400 > >> [  221.872445] panfrost 13040000.gpu: Features: L2:0x07120206 > >> Shader:0x00000000 Tiler:0x00000809 Mem:0x1 MMU:0x00002830 AS:0xff JS:0x7 > >> [  221.872449] panfrost 13040000.gpu: shader_present=0x7 l2_present=0x1 > >> [  221.873526] panfrost 13040000.gpu: error powering up gpu stack > >> [  221.878088] [drm] Initialized panfrost 1.1.0 20180908 for > >> 13040000.gpu on minor 2 > >> [  221.940817] panfrost 13040000.gpu: error powering up gpu stack > >> [  222.018233] panfrost 13040000.gpu: error powering up gpu stack > >> (repeated) > > > > It's interesting that it's only the stack that is failing. In hardware > > there's a dependency: L2->stack->shader - so in theory the shader cores > > shouldn't be able to power up either. There are some known hardware bugs > > here though[1]: > > > >     MODULE_PARM_DESC(corestack_driver_control, > >             "Let the driver power on/off the GPU core stack > > independently " > >             "without involving the Power Domain Controller. This should " > >             "only be enabled on platforms for which integration of the > > PDC " > >             "to the Mali GPU is known to be problematic."); > > > > [1] > > https://github.com/ianmacd/d2s/blob/master/drivers/gpu/arm/b_r16p0/backend/gpu/mali_kbase_pm_driver.c#L57 > > > > > > It might be worth just dropping the code for powering up/down stacks and > > let the GPU's own dependency management handle it. > > FWIW I remember digging into that same message a while back (although > I've forgotten which particular GPU I was playing with at the time), and > concluded that the STACK_PWRON/STACK_READY registers might just not be > implemented on some GPUs, They are indeed not implemented on some GPUs. Specifically none of the Midgard GPUs. I believe G71 also doesn't have it. However the register addresses were picked so that on these older GPUs they should read-as-zero and write-ignore so this shouldn't actually cause any problems. > and/or this easy-to-overlook register bit > could be some kind of enable for the functionality: > > https://github.com/ianmacd/d2s/blob/master/drivers/gpu/arm/b_r16p0/backend/gpu/mali_kbase_pm_driver.c#L1631 > > Since even in kbase this is all behind an 'expert' config option, I'm > inclined to agree that just dropping it from panfrost unless and until > it proves necessary is probably preferable to adding more logic and > inscrutable register-magic. Indeed - I'll post a patch removing it. Thanks, Steve > Robin. > > > > > Steve > > > >> > >> So the GPU is probed, but there's an issue when powering up the STACK, > >> not > >> quite sure why, I'll try to have a deeper look, at some point. > >> > >> Thanks! > >> > >> Nicolas > >> > >> v2: > >>   - Use sram instead of mali_sram as SRAM supply name. > >>   - Rename mali@ to gpu@. > >>   - Add dt-bindings changes > >>   - Stacking patches after the device tree change that allow basic > >>     probing (still incomplete and broken). > >> > >> Nicolas Boichat (7): > >>    dt-bindings: gpu: mali-bifrost: Add Mediatek MT8183 > >>    arm64: dts: mt8183: Add node for the Mali GPU > >>    drm/panfrost: Improve error reporting in panfrost_gpu_power_on > >>    drm/panfrost: Add support for a second regulator for the GPU > >>    drm/panfrost: Add support for multiple power domain support > >>    RFC: drm/panfrost: Add bifrost compatible string > >>    RFC: drm/panfrost: devfreq: Add support for 2 regulators > >> > >>   .../bindings/gpu/arm,mali-bifrost.yaml        |  20 ++++ > >>   arch/arm64/boot/dts/mediatek/mt8183-evb.dts   |   7 ++ > >>   arch/arm64/boot/dts/mediatek/mt8183.dtsi      | 104 +++++++++++++++++ > >>   drivers/gpu/drm/panfrost/panfrost_devfreq.c   |  18 +++ > >>   drivers/gpu/drm/panfrost/panfrost_device.c    | 108 ++++++++++++++++-- > >>   drivers/gpu/drm/panfrost/panfrost_device.h    |   7 ++ > >>   drivers/gpu/drm/panfrost/panfrost_drv.c       |   1 + > >>   drivers/gpu/drm/panfrost/panfrost_gpu.c       |  15 ++- > >>   8 files changed, 267 insertions(+), 13 deletions(-) > >> > > > > _______________________________________________ > > dri-devel mailing list > > dri-devel@lists.freedesktop.org > > https://lists.freedesktop.org/mailman/listinfo/dri-devel