From patchwork Tue Sep 1 15:10:16 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 264806 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=-13.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED, USER_AGENT_GIT autolearn=ham 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 93135C433E6 for ; Tue, 1 Sep 2020 15:19:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 64EB62166E for ; Tue, 1 Sep 2020 15:19:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1598973578; bh=m5M8Awz22GmrEwV0BJ4+h7A02qBUcB/cu5vWpcC9nPo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=RlkcsOIcFoDenVxwjR0RO13KQ8hJhDrjSgg5glHNrHTljfyD5bpSxIgSqIMqSUo3z PJMg58sZiNt5wlF7L8EO+c6B6LK71ZkOc3OJ8FI3TrosVhFcQDGHcoVygQ58aCp8p7 FWUfELPhuJv7JA2BstwgAZmGykJ8EtEcAOKwzIPU= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729269AbgIAPTe (ORCPT ); Tue, 1 Sep 2020 11:19:34 -0400 Received: from mail.kernel.org ([198.145.29.99]:37762 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729140AbgIAPTF (ORCPT ); Tue, 1 Sep 2020 11:19:05 -0400 Received: from localhost (83-86-74-64.cable.dynamic.v4.ziggo.nl [83.86.74.64]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 5C5AA206FA; Tue, 1 Sep 2020 15:19:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1598973544; bh=m5M8Awz22GmrEwV0BJ4+h7A02qBUcB/cu5vWpcC9nPo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=cRRYGMaGUDD1DSXWiG/2TWIWskuRx0KWozTXcv2F0xs/vTXvJdGk/DGl0ikdNxRyO sXyiUZv68wuecrPYxZZtaJXodO03wlINQ9MKjP0Eo/4BBgy1P3l7uhOCEfJV93g8qZ aFYFG+R9Kpq0ExsBm91dJWMYQorvZ6Of0PN+EQjo= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Sean Young , Mauro Carvalho Chehab , Sasha Levin Subject: [PATCH 4.14 42/91] media: gpio-ir-tx: improve precision of transmitted signal due to scheduling Date: Tue, 1 Sep 2020 17:10:16 +0200 Message-Id: <20200901150930.228808263@linuxfoundation.org> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20200901150928.096174795@linuxfoundation.org> References: <20200901150928.096174795@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Sean Young [ Upstream commit ea8912b788f8144e7d32ee61e5ccba45424bef83 ] usleep_range() may take longer than the max argument due to scheduling, especially under load. This is causing random errors in the transmitted IR. Remove the usleep_range() in favour of busy-looping with udelay(). Signed-off-by: Sean Young Signed-off-by: Mauro Carvalho Chehab Signed-off-by: Sasha Levin --- drivers/media/rc/gpio-ir-tx.c | 7 +------ 1 file changed, 1 insertion(+), 6 deletions(-) diff --git a/drivers/media/rc/gpio-ir-tx.c b/drivers/media/rc/gpio-ir-tx.c index cd476cab97820..4e70b67ccd181 100644 --- a/drivers/media/rc/gpio-ir-tx.c +++ b/drivers/media/rc/gpio-ir-tx.c @@ -87,13 +87,8 @@ static int gpio_ir_tx(struct rc_dev *dev, unsigned int *txbuf, // space edge = ktime_add_us(edge, txbuf[i]); delta = ktime_us_delta(edge, ktime_get()); - if (delta > 10) { - spin_unlock_irqrestore(&gpio_ir->lock, flags); - usleep_range(delta, delta + 10); - spin_lock_irqsave(&gpio_ir->lock, flags); - } else if (delta > 0) { + if (delta > 0) udelay(delta); - } } else { // pulse ktime_t last = ktime_add_us(edge, txbuf[i]);