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=-3.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,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 277C3C432BE for ; Tue, 10 Aug 2021 20:33:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0598560FDA for ; Tue, 10 Aug 2021 20:33:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233375AbhHJUd3 (ORCPT ); Tue, 10 Aug 2021 16:33:29 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35994 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233083AbhHJUd2 (ORCPT ); Tue, 10 Aug 2021 16:33:28 -0400 Received: from galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1821AC0613C1; Tue, 10 Aug 2021 13:33:06 -0700 (PDT) From: Thomas Gleixner DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1628627582; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=VmNO/6PZX/ukpmKUxgFb784BLjZWMf0I28FYYc/qH+Q=; b=geT0QKa+FGH9C4lt7qI+awsmOAPGEPnuKNhteiIPNmgcQaziJdqJBjQY00zPcEFuZmuBmB oOh5oInajQrBVbX67j2q2iD9BWXDlbwu+g8lE5rVLGMCIErd9No4tCqHdEseYSHugHI1zg zHWyd3cFWnmyd3BVs5lJX5LyVJozvZFjkzQaV/wHC6r+3d7TYpJlg2oG+v1mmVFYWDsD/m yJWjYV/irDIoGlQPhZaJOQK49VMOnb5dU12SyIIcmXk83MxnTdGzx+YuXNArtOFDUHB7qb PYtamAOAZKRt461Vh7cGXI2uzw3URsGPaKwXtzw2i4OBmySXjMRNqhkygKAVAg== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1628627582; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=VmNO/6PZX/ukpmKUxgFb784BLjZWMf0I28FYYc/qH+Q=; b=9RUz3+Q/kDOp5LEbghaANWydLhI9VhI74udmE/onDz0uMdyQg6tGx5YzKhMZhoGJCeflAI 3S/vPf9bzVldkWCw== To: Valentin Schneider , linux-kernel@vger.kernel.org, linux-rt-users@vger.kernel.org Cc: Will Deacon , Mark Rutland , Marc Zyngier , Sebastian Andrzej Siewior , Mel Gorman , Linus Walleij , Bartosz Golaszewski , linux-gpio@vger.kernel.org Subject: Re: [SPLAT 3/3] gpio: dwapb: Sleeping spinlocks down IRQ mapping In-Reply-To: <20210810134127.1394269-4-valentin.schneider@arm.com> References: <20210810134127.1394269-1-valentin.schneider@arm.com> <20210810134127.1394269-4-valentin.schneider@arm.com> Date: Tue, 10 Aug 2021 22:33:01 +0200 Message-ID: <87v94doxaa.ffs@tglx> MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Aug 10 2021 at 14:41, Valentin Schneider wrote: > [ 11.549824] rt_spin_lock (kernel/locking/rtmutex.c:1641 (discriminator 4) kernel/locking/spinlock_rt.c:30 (discriminator 4) kernel/locking/spinlock_rt.c:36 (discriminator 4) kernel/locking/spinlock_rt.c:44 (discriminator 4)) > [ 11.549827] dwapb_irq_ack (drivers/gpio/gpio-dwapb.c:151 drivers/gpio/gpio-dwapb.c:233) gpio_dwapb > [ 11.549831] __irq_do_set_handler (kernel/irq/chip.c:414 kernel/irq/chip.c:406 kernel/irq/chip.c:1009) > [ 11.549833] __irq_set_handler (kernel/irq/internals.h:178 kernel/irq/chip.c:1053) This is gpio_chip->bgpio_lock which is a regular spinlock. AFAICT this lock should merely serializing access to MMIO registers, so it should not be a problem to make this lock raw. Except for the obligatory exception: grgpio_irq_handler() holds that lock from the demultiplexing handler and invokes all handlers for the individual GPIOs which have interrupts enabled without ever consulting a pending register. That drivers usage of that lock is interesting in general, see grgpio_map_irq() for illustration. Quality stuff for mission critical systems... But nevertheless it should just work with a raw lock on RT AFACIT. Thanks, tglx