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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 588E8C433EF for ; Wed, 6 Oct 2021 11:13:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4395C611C5 for ; Wed, 6 Oct 2021 11:13:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238536AbhJFLO5 (ORCPT ); Wed, 6 Oct 2021 07:14:57 -0400 Received: from mail.kernel.org ([198.145.29.99]:38666 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238530AbhJFLO4 (ORCPT ); Wed, 6 Oct 2021 07:14:56 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 6100761166; Wed, 6 Oct 2021 11:13:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1633518784; bh=nP9Gz40YheGjmXGenK6aSQJa95wN7Jthsqmc5DCDn7Q=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=qnPT1sM7n190/8tbmwVkPshN+Yet+pHEtVWMzLgnG5IdR2AiKNRBU6eNMgQ06Gz/8 hgAZZGP1rfPfIe4lcJw96h7naHCRNg6Kelq+Vxv2gOlqhVvmswWf9MFLSs59SQCaV6 XkZipMkXfXSxevTtMFCQ8zdE0EKtzQsbxdQeDNNXV+FqZSmMANlQ9MtzxO2rJT11Mk rkaYnQb0sMYkGLiLMpGOUAG08NXBZXpOL1mUpKitWufignLyMT4DzUAFDIOFWDTjlF AOOD88BgY6Z5sZxFyBHToavLtIvxLkifIzwyivoybKWu/3dNFhVrh0HibAqmQSL3kt aMKKrEjv9mVtA== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Thomas Gleixner , alsa-devel@alsa-project.org, Takashi Iwai , Jaroslav Kysela , Takashi Iwai , Sasha Levin Subject: [PATCH MANUALSEL 4.19 2/2] ALSA: pcsp: Make hrtimer forwarding more robust Date: Wed, 6 Oct 2021 07:12:59 -0400 Message-Id: <20211006111259.264427-2-sashal@kernel.org> X-Mailer: git-send-email 2.33.0 In-Reply-To: <20211006111259.264427-1-sashal@kernel.org> References: <20211006111259.264427-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Thomas Gleixner [ Upstream commit f2ff7147c6834f244b8ce636b12e71a3bd044629 ] The hrtimer callback pcsp_do_timer() prepares rearming of the timer with hrtimer_forward(). hrtimer_forward() is intended to provide a mechanism to forward the expiry time of the hrtimer by a multiple of the period argument so that the expiry time greater than the time provided in the 'now' argument. pcsp_do_timer() invokes hrtimer_forward() with the current timer expiry time as 'now' argument. That's providing a periodic timer expiry, but is not really robust when the timer callback is delayed so that the resulting new expiry time is already in the past which causes the callback to be invoked immediately again. If the timer is delayed then the back to back invocation is not really making it better than skipping the missed periods. Sound is distorted in any case. Use hrtimer_forward_now() which ensures that the next expiry is in the future. This prevents hogging the CPU in the timer expiry code and allows later on to remove hrtimer_forward() from the public interfaces. Signed-off-by: Thomas Gleixner Cc: alsa-devel@alsa-project.org Cc: Takashi Iwai Cc: Jaroslav Kysela Link: https://lore.kernel.org/r/20210923153339.623208460@linutronix.de Signed-off-by: Takashi Iwai Signed-off-by: Sasha Levin --- sound/drivers/pcsp/pcsp_lib.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/sound/drivers/pcsp/pcsp_lib.c b/sound/drivers/pcsp/pcsp_lib.c index 8f0f05bbc081..23a15d892e50 100644 --- a/sound/drivers/pcsp/pcsp_lib.c +++ b/sound/drivers/pcsp/pcsp_lib.c @@ -145,7 +145,7 @@ enum hrtimer_restart pcsp_do_timer(struct hrtimer *handle) if (pointer_update) pcsp_pointer_update(chip); - hrtimer_forward(handle, hrtimer_get_expires(handle), ns_to_ktime(ns)); + hrtimer_forward_now(handle, ns_to_ktime(ns)); return HRTIMER_RESTART; } -- 2.33.0