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 66D4CC54E58 for ; Mon, 18 Mar 2024 14:18:20 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 88F4910EF1F; Mon, 18 Mar 2024 14:18:19 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=collabora.com header.i=@collabora.com header.b="mtcxD59m"; dkim-atps=neutral Received: from madrid.collaboradmins.com (madrid.collaboradmins.com [46.235.227.194]) by gabe.freedesktop.org (Postfix) with ESMTPS id 0A5D410EF1F for ; Mon, 18 Mar 2024 14:18:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=collabora.com; s=mail; t=1710771496; bh=otcoHtF6sASMgicPcPM31Hta1yw/5DShqfaSsJ3gTdY=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=mtcxD59mmjCTky4QUHI4Ctxe7pzPHPEroiEZEOxmlMwyNwOPlENt9lSHXZ6mgtf8Q KzvgMct+JNErFGI+dT399TajjE7PCz+osuKcqGJx9Tq1w/qqvon+VmPtkikS9vMP2j UUIbhQs4aKJjPydvMRZKpVBbUGOpdllaEEFXK6Neavxr6dZBFjwRxBiHdjTlBvhTlh UQQZqhT/jl+jn73ZG/GGJF54wUD6kgNrtbSjav5VqEgGFnLZFXISlX5HsJ+76j3e9/ ZkXA9lX91xPi6fT5CXaK90gr1fFBUnvcrwI38bqETSoYNSeisPsoApf+sD0aevnqky v5+/WEYLgqc+w== Received: from localhost (cola.collaboradmins.com [195.201.22.229]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) (Authenticated sender: bbrezillon) by madrid.collaboradmins.com (Postfix) with ESMTPSA id 9F0DA37811D1; Mon, 18 Mar 2024 14:18:15 +0000 (UTC) Date: Mon, 18 Mar 2024 15:18:14 +0100 From: Boris Brezillon To: Steven Price Cc: Liviu Dudau , dri-devel@lists.freedesktop.org, Robin Murphy , kernel@collabora.com, kernel test robot Subject: Re: [PATCH] drm/panthor: Fix the CONFIG_PM=n case Message-ID: <20240318151814.725002c5@collabora.com> In-Reply-To: <5c9257cb-8307-4f9e-9323-2ed367c48a11@arm.com> References: <20240318085855.994179-1-boris.brezillon@collabora.com> <2af13565-f3d7-47c3-8083-da86669a34e1@arm.com> <20240318140815.44de8110@collabora.com> <5c9257cb-8307-4f9e-9323-2ed367c48a11@arm.com> Organization: Collabora X-Mailer: Claws Mail 4.2.0 (GTK 3.24.38; x86_64-redhat-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII 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 Mon, 18 Mar 2024 13:49:52 +0000 Steven Price wrote: > 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. Uh, you're right, sorry for the brain fart. This is being said, I see no other driver selecting the PM option directly (if you grep for 'select PM' in drivers/, you'll find occurrences in drivers/soc, but those are under ARCH_/SOC_ options, which means they are indirectly arch/platform dependent, not driver dependent). I'm really not sure selecting PM here from a driver is right to be honest. > > > 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. Looks like the kbuild bot didn't catch that yet :-). > > 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 :) Mind sending a fix for that?