From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D6EE834888F for ; Mon, 13 Jul 2026 20:21:45 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783974107; cv=none; b=O2oOUKthKqsSkmD9yTDJdQbk22EWNwmc1K+1rVa1GSs8qh4flgOTYtjssPo8xXtsge1Vzv9rCD11P4cAgn5hoPHCfwsdy7ac8SKxP0off9OgSX7smWvuU8T9e2o+YN0kqOEHuddd/FudWoEYR1NQsheYC45t6s4LNLLCktyRopU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783974107; c=relaxed/simple; bh=/hzZwS+UmTxeNhC7S7FLsBZ6Y2cxuuMFf5cxBynTVGY=; h=Date:Message-ID:From:To:Cc:Subject:In-Reply-To:References: MIME-Version:Content-Type; b=marR1xSm/yFjlJF2xm25MQUEegQ8ym8noUARQdpwyNkakV6vSRSva4j0tJ4eNmhsGuDQXlSYIoG+FbUe2wHMOFYVRCDlj7/acAOdkYA/CNcdEo1GX07GDEL8SaMf9OLRqi5UlaM6qDIzz2H/ncsy9Wqh4l8H5Ml3SZm07yUkt+8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=kDbjAez9; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="kDbjAez9" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B3DDF1F000E9; Mon, 13 Jul 2026 20:21:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1783974105; bh=Td3Tx5KtkuKrg85J0/Fk7nX8Etrw595QfhQMDVHw4Xs=; h=Date:From:To:Cc:Subject:In-Reply-To:References; b=kDbjAez9p34Xda/BebvIXNCVDlcc/oP44J2jS/7Rcj5lf6XTxZKdCfnnCF78RhRd1 QigVDFm1R4BOvlz+nQV5zOVLuHZUI/mMT7gvHo//VJmBNHs6BDv3wZjgOlWtbAToWx xSbZxNrJKSw2Q5RI7CCUIJ/CmURn5ZVisN4XUg/obIDevBWQhkRMMqpA4zhh4ZTr5i B03UUyxBFAgwrtD8HHB/xgG0pZ4fcGl8v250JSw3p/1DP6l3HiKVUAZMwuc2IQOzOv XdW8naOOdhabepHVJA8uGxacdglq3ADCwIyaEg3COmvzh1NShvhOTUu9IAlBZPiEam EKt2oOW7atc7A== Received: from sofa.misterjones.org ([185.219.108.64] helo=lobster-girl.misterjones.org) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.98.2) (envelope-from ) id 1wjN9r-00000004dOb-21Fy; Mon, 13 Jul 2026 20:21:43 +0000 Date: Mon, 13 Jul 2026 21:23:33 +0100 Message-ID: <877bmy63lm.wl-maz@kernel.org> From: Marc Zyngier To: Florian Fainelli Cc: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, John , Daniel Drake , Marek Szyprowski , Daniel Lezcano , Thomas Gleixner , Mark Rutland Subject: Re: [PATCH] clocksource/drivers/arm_arch_timer: Workaround bcm2712 broken EL2 virtual timer In-Reply-To: <1c23b437-609c-470a-8b14-34288cb5aaa3@broadcom.com> References: <20260710080958.491620-1-maz@kernel.org> <1c23b437-609c-470a-8b14-34288cb5aaa3@broadcom.com> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI-EPG/1.14.7 (Harue) FLIM-LB/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL-LB/10.8 EasyPG/1.0.0 Emacs/30.1 (aarch64-unknown-linux-gnu) MULE/6.0 (HANACHIRUSATO) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") Content-Type: text/plain; charset=US-ASCII X-SA-Exim-Connect-IP: 185.219.108.64 X-SA-Exim-Rcpt-To: florian.fainelli@broadcom.com, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, therealgraysky@proton.me, dan@reactivated.net, m.szyprowski@samsung.com, daniel.lezcano@linaro.org, tglx@linutronix.de, mark.rutland@arm.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false On Mon, 13 Jul 2026 17:15:35 +0100, Florian Fainelli wrote: > > On 7/10/26 01:09, Marc Zyngier wrote: > > It appears that the bcm2712 SoC found in the relatively popular > > RPi5 has a broken EL2 virtual timer. > > > > We do not know the reason why the timer isn't working (the timer > > is ticking, but the interrupt never fires), and the SoC vendor > > doesn't communicate on the reason why this isn't working, leaving > > users and maintainers in the dark. > > > > Paper over the issue by detecting the broken HW, falling back to > > the physical timer instead, and let the user know about it. > > Also taint the kernel as the machine is definitely not compliant > > with the spec, and we don't know what else is wrong with it. > > > > Reported-by: John > > Reported-by: Daniel Drake > > Reported-by: Marek Szyprowski > > Signed-off-by: Marc Zyngier > > Cc: Florian Fainelli > > Cc: Daniel Lezcano > > Cc: Thomas Gleixner > > Cc: Mark Rutland > > Acked-by: Florian Fainelli > > We know why now: the virtual interrupt timer line was never connected > in the first place because it was not clarified that it was a > requirement. Dangling wires coming out of the CPUs don't ring any alarm bell at integration time? Amazing. Makes you wonder what else they forgot to connect... Is there an erratum number that we can refer to for documentation purposes? M. -- Jazz isn't dead. It just smells funny.