From nobody Fri Dec 19 11:30:24 2025 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0857EEE020F for ; Wed, 13 Sep 2023 21:27:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232359AbjIMV1g (ORCPT ); Wed, 13 Sep 2023 17:27:36 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57968 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229698AbjIMV1b (ORCPT ); Wed, 13 Sep 2023 17:27:31 -0400 Received: from mail-pg1-x534.google.com (mail-pg1-x534.google.com [IPv6:2607:f8b0:4864:20::534]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A0B661724 for ; Wed, 13 Sep 2023 14:27:27 -0700 (PDT) Received: by mail-pg1-x534.google.com with SMTP id 41be03b00d2f7-577dad08512so695452a12.1 for ; Wed, 13 Sep 2023 14:27:27 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; t=1694640447; x=1695245247; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=oOiFJlPGyJUavNNVJMIMcGzvlYAGe09SF66xWdVaxyU=; b=aP1CrSMPFY/9BpGHOgfmmkbW0TKI9OKa0TkBfI4Q6dG7IY75LrR1u7SseAg0gt5zaY YZhHEEZRwh0ykb9Bcx+/aHeT2UNCT64SnjpbzVzNVD2hopL543cXm4yOjppFRsEKGok5 Z/10+RP7OdA67IIdWydENjNRC6wJ8ap9/JL5s= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1694640447; x=1695245247; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=oOiFJlPGyJUavNNVJMIMcGzvlYAGe09SF66xWdVaxyU=; b=KiOTj4jqq6Iupsf2O53IYhab68xDWNUVaWebBtRAOW54rIryAoJfYiBPGDV0dA8aZ0 1V0HshVrr5yxEjZnSiO8iAqgJwvyKxIaDb2tJaaupNyeAyzQsYDQJY2JMUzTXagAiQ/8 D2zTL2XWNMpenlOlnvWIMIoKKZIenqcCXGy+sZlwDy1tnzRJbwfhdpYgxVnFC2Mfb1DW mA+zUwtenBTEIDG1LnL1zR9cWw5FUiUK7jkl+stlkDh+KpLWg/UGJ7d0Jn+zpMHqI3Ka fySNsws1fCmKDuz54tnF/YN3QiN9iY/rsoDcbuo5/1KB8TqJ0waR+oqUbqZDd951KnQC KTtw== X-Gm-Message-State: AOJu0YyQKAF61QNAN2lY/NtFIegbUjbtOnivrZa26SiuYSDtswOR9e9V xXJdR7Qi5Ba8+VBxd+somsyTpg== X-Google-Smtp-Source: AGHT+IGyULUVZNu+bUP/MqMEKr8RaVU+CWUNozYQ8it166LT6PCoR6pmCH6eo+YA6LRjoue3V82dXQ== X-Received: by 2002:a17:90b:30c2:b0:26f:392f:f901 with SMTP id hi2-20020a17090b30c200b0026f392ff901mr5552309pjb.14.1694640447120; Wed, 13 Sep 2023 14:27:27 -0700 (PDT) Received: from smtp.gmail.com ([2620:15c:11a:201:ae97:c6dc:1d98:494f]) by smtp.gmail.com with ESMTPSA id a10-20020a17090ad80a00b0025bdc3454c6sm1923976pjv.8.2023.09.13.14.27.26 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 13 Sep 2023 14:27:26 -0700 (PDT) From: Stephen Boyd To: Mika Westerberg , Hans de Goede , Mark Gross Cc: linux-kernel@vger.kernel.org, patches@lists.linux.dev, platform-driver-x86@vger.kernel.org, Andy Shevchenko , Kuppuswamy Sathyanarayanan , Prashant Malani Subject: [PATCH v4 1/4] platform/x86: intel_scu_ipc: Check status after timeout in busy_loop() Date: Wed, 13 Sep 2023 14:27:19 -0700 Message-ID: <20230913212723.3055315-2-swboyd@chromium.org> X-Mailer: git-send-email 2.42.0.283.g2d96d420d3-goog In-Reply-To: <20230913212723.3055315-1-swboyd@chromium.org> References: <20230913212723.3055315-1-swboyd@chromium.org> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" It's possible for the polling loop in busy_loop() to get scheduled away for a long time. status =3D ipc_read_status(scu); // status =3D IPC_STATUS_BUSY if (!(status & IPC_STATUS_BUSY)) If this happens, then the status bit could change while the task is scheduled away and this function would never read the status again after timing out. Instead, the function will return -ETIMEDOUT when it's possible that scheduling didn't work out and the status bit was cleared. Bit polling code should always check the bit being polled one more time after the timeout in case this happens. Fix this by reading the status once more after the while loop breaks. The readl_poll_timeout() macro implements all of this, and it is shorter, so use that macro here to consolidate code and fix this. There were some concerns with using readl_poll_timeout() because it uses timekeeping, and timekeeping isn't running early on or during the late stages of system suspend or early stages of system resume, but an audit of the code concluded that this code isn't called during those times so it is safe to use the macro. Cc: Prashant Malani Reviewed-by: Andy Shevchenko Reviewed-by: Mika Westerberg Reviewed-by: Kuppuswamy Sathyanarayanan Fixes: e7b7ab3847c9 ("platform/x86: intel_scu_ipc: Sleeping is fine when po= lling") Signed-off-by: Stephen Boyd Reviewed-by: Ilpo J=C3=A4rvinen --- drivers/platform/x86/intel_scu_ipc.c | 19 ++++++++----------- 1 file changed, 8 insertions(+), 11 deletions(-) diff --git a/drivers/platform/x86/intel_scu_ipc.c b/drivers/platform/x86/in= tel_scu_ipc.c index 6851d10d6582..4c774ee8bb1b 100644 --- a/drivers/platform/x86/intel_scu_ipc.c +++ b/drivers/platform/x86/intel_scu_ipc.c @@ -19,6 +19,7 @@ #include #include #include +#include #include #include =20 @@ -231,19 +232,15 @@ static inline u32 ipc_data_readl(struct intel_scu_ipc= _dev *scu, u32 offset) /* Wait till scu status is busy */ static inline int busy_loop(struct intel_scu_ipc_dev *scu) { - unsigned long end =3D jiffies + IPC_TIMEOUT; + u8 status; + int err; =20 - do { - u32 status; + err =3D readx_poll_timeout(ipc_read_status, scu, status, !(status & IPC_S= TATUS_BUSY), + 100, jiffies_to_usecs(IPC_TIMEOUT)); + if (err) + return err; =20 - status =3D ipc_read_status(scu); - if (!(status & IPC_STATUS_BUSY)) - return (status & IPC_STATUS_ERR) ? -EIO : 0; - - usleep_range(50, 100); - } while (time_before(jiffies, end)); - - return -ETIMEDOUT; + return (status & IPC_STATUS_ERR) ? -EIO : 0; } =20 /* Wait till ipc ioc interrupt is received or timeout in 10 HZ */ --=20 https://chromeos.dev