From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pg1-f176.google.com (mail-pg1-f176.google.com [209.85.215.176]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id CB33E22EF4 for ; Wed, 13 Sep 2023 21:27:27 +0000 (UTC) Received: by mail-pg1-f176.google.com with SMTP id 41be03b00d2f7-56f84de64b9so234911a12.1 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=lists.linux.dev; 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=aMc5pFXt5picW3RTwabVjA6//embyoWfqkrJ7NZkKoY9CndKEYZYkFQ/vzC0FR1KeF 1ARpvU9EMf52wmcvKSKA0rr+zcQ5mXGnmZtwl1O4xN3egMBCrX1ELrUPSSwgDUoNUI7X mW7BNY9314nm0QrUbJ77R6AWuBF4J6Zij73jo= 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=siPM4fLeAle/NTPFRRV1CHLkkI3fgaPOS8+3SP4uqrA0+S8pcFvCU8LeuboFKhKdmy VCz2ZZ0Sk6lj0amhk/wwre4J3yLH737aCgncgXTsH81RKDM+c0Ae9qcySVNtub1E246z vbSiVf96g9OTSrdWxrjLiPlKQA1r7W/y+6VBhsvZ8iCH39UXsmcWZEpOcnJaIBCRaByX dpgqUOnD7tbPK6stZ4lm3VlhjtqiUAxNwuBgKwsMFwJxi+ChA7k1caWSCY286sDxRGN3 OPncO9J9/lr9yNABOsX67P1jfBXIi7KgWc7O6DVIsR/Z+KL4rdtw88RCK9eS+hRnT3ay kyvg== X-Gm-Message-State: AOJu0Yw0xUy1KisPczoCYsjuj0dIVD5ijHdM+QZf9x1TV0X/bUi3bT6z vPVjMn2xmsEyUigLwKmiONkJ6Q== 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> Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit It's possible for the polling loop in busy_loop() to get scheduled away for a long time. status = ipc_read_status(scu); // status = 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 polling") Signed-off-by: Stephen Boyd --- 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/intel_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 @@ -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 = jiffies + IPC_TIMEOUT; + u8 status; + int err; - do { - u32 status; + err = readx_poll_timeout(ipc_read_status, scu, status, !(status & IPC_STATUS_BUSY), + 100, jiffies_to_usecs(IPC_TIMEOUT)); + if (err) + return err; - status = 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; } /* Wait till ipc ioc interrupt is received or timeout in 10 HZ */ -- https://chromeos.dev