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 gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 4BC45C54E5D for ; Mon, 18 Mar 2024 13:49:57 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 6905710F779; Mon, 18 Mar 2024 13:49:56 +0000 (UTC) Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by gabe.freedesktop.org (Postfix) with ESMTP id D1CD910F77A for ; Mon, 18 Mar 2024 13:49:53 +0000 (UTC) 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 D18D4DA7; Mon, 18 Mar 2024 06:50:27 -0700 (PDT) Received: from [10.57.12.69] (unknown [10.57.12.69]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id C59773F67D; Mon, 18 Mar 2024 06:49:51 -0700 (PDT) Message-ID: <5c9257cb-8307-4f9e-9323-2ed367c48a11@arm.com> Date: Mon, 18 Mar 2024 13:49:52 +0000 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] drm/panthor: Fix the CONFIG_PM=n case Content-Language: en-GB To: Boris Brezillon Cc: Liviu Dudau , dri-devel@lists.freedesktop.org, Robin Murphy , kernel@collabora.com, kernel test robot References: <20240318085855.994179-1-boris.brezillon@collabora.com> <2af13565-f3d7-47c3-8083-da86669a34e1@arm.com> <20240318140815.44de8110@collabora.com> From: Steven Price In-Reply-To: <20240318140815.44de8110@collabora.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" On 18/03/2024 13:08, Boris Brezillon wrote: > On Mon, 18 Mar 2024 11:31:05 +0000 > Steven Price wrote: > >> On 18/03/2024 08:58, Boris Brezillon wrote: >>> Putting a hard dependency on CONFIG_PM is not possible because of a >>> circular dependency issue, and it's actually not desirable either. In >>> order to support this use case, we forcibly resume at init time, and >>> suspend at unplug time. >>> >>> Reported-by: kernel test robot >>> Closes: https://lore.kernel.org/oe-kbuild-all/202403031944.EOimQ8WK-lkp@intel.com/ >>> Signed-off-by: Boris Brezillon >> >> Reviewed-by: Steven Price >> >>> --- >>> Tested by faking CONFIG_PM=n in the driver (basically commenting >>> all pm_runtime calls, and making the panthor_device_suspend/resume() >>> calls unconditional in the panthor_device_unplug/init() path) since >>> CONFIG_ARCH_ROCKCHIP selects CONFIG_PM. Seems to work fine, but I >>> can't be 100% sure this will work correctly on a platform that has >>> CONFIG_PM=n. >> >> The same - I can't test this properly :( >> >> Note that the other option (which AFAICT doesn't cause any problems) is >> to "select PM" rather than depend on it - AIUI the 'select' dependency >> is considered in the opposite direction by kconfig so won't cause the >> dependency loop. > > Doesn't seem to work with COMPILE_TEST though? I mean, we need > something like > > depends on ARM || ARM64 || (COMPILE_TEST && PM) > ... > select PM > > but kconfig doesn't like that Why do we need the "&& PM" part? Just: depends on ARM || ARM64 || COMPILE_TEST ... select PM Or at least that appears to work for me. > drivers/gpu/drm/panthor/Kconfig:3:error: recursive dependency detected! > drivers/gpu/drm/panthor/Kconfig:3: symbol DRM_PANTHOR depends on > PM kernel/power/Kconfig:183: symbol PM is selected by DRM_PANTHOR > > which id why I initially when for a depends on PM > > >> Of course if there is actually anyone who has a >> platform which can be built !CONFIG_PM then that won't help. But the >> inability of anyone to actually properly test this configuration does >> worry me a little. > > Well, as long as it doesn't regress the PM behavior, I think I'm happy > to take the risk. Worst case scenario, someone complains that this is > not working properly when they do the !PM bringup :-). Indeed, I've no objection to this patch - although I really should have compiled tested it as Robin pointed out ;) But one other thing I've noticed when compile testing it - we don't appear to have fully fixed the virt_to_pfn() problem. On x86 with COMPILE_TEST I still get an error. Looking at the code it appears that virt_to_pfn() isn't available on x86... it overrides asm/page.h and doesn't provide a definition. The definition on x86 is hiding in asm/xen/page.h. Outside of arch code it's only drivers/xen that currently uses that function. So I guess it's probably best to do a PFN_DOWN(virt_to_phys(...)) instead. Or look to fix x86 :) Steve