From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 199C7763F6; Wed, 21 Feb 2024 13:22:04 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708521725; cv=none; b=gQ+SeKLXqQw3MqsgmmgKiTZhHxeNbW9rIFhHmWchVLmJ7f3JAn0gXu+xbanduMtLJR4cGsPRMb6Uq1aHATmPZGCM9wltbWXALPSAmnpqIisGMIS93z9usIPVCikuFvDjyqOx8lZUv5MhF1pqaTOxqnOSyGPdiC0hJWkAjF4ATSY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708521725; c=relaxed/simple; bh=SDvzDTtArtkXy++YzCaqdmyFRiLfCLp2mMs2huSqy4I=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=sGn5RGiEvJ5YVlNHBG00o+5Ct7vazUh6NxzquYji4yd848q07SqXLId6ZsSVlypsK3ySti3nMesi03uYEwOX6zXrmE4hqJLLMSLSypr/sMV17QE7hnOFMGWnHSaelTtg1eRm1IdiUcqV0MQZP9N0GJOFGr1j9V+Vc+do1cvs+IU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=kLeZ0631; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="kLeZ0631" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1F98BC433F1; Wed, 21 Feb 2024 13:22:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1708521724; bh=SDvzDTtArtkXy++YzCaqdmyFRiLfCLp2mMs2huSqy4I=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=kLeZ0631hftkP7yGmK+yExg6J/q19MJo8a0/HXQbJ7ErnhWYOmM8HK4nZHfowNRz9 hsgzwOCNPF0Nwd00PIGb+0ZVb58bJxbwhQ6nktyiz6ZbL6bnzrQ1VF7K/m8sXwTJb6 jzKNAt/2pUVvl6dKVsHrKpSb8tN5qLUDYJM58NCU= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, =?UTF-8?q?Jan=20Kundr=C3=A1t?= , Hugo Villeneuve Subject: [PATCH 4.19 188/202] serial: max310x: improve crystal stable clock detection Date: Wed, 21 Feb 2024 14:08:09 +0100 Message-ID: <20240221125937.880702899@linuxfoundation.org> X-Mailer: git-send-email 2.43.2 In-Reply-To: <20240221125931.742034354@linuxfoundation.org> References: <20240221125931.742034354@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 4.19-stable review patch. If anyone has any objections, please let me know. ------------------ From: Hugo Villeneuve commit 93cd256ab224c2519e7c4e5f58bb4f1ac2bf0965 upstream. Some people are seeing a warning similar to this when using a crystal: max310x 11-006c: clock is not stable yet The datasheet doesn't mention the maximum time to wait for the clock to be stable when using a crystal, and it seems that the 10ms delay in the driver is not always sufficient. Jan Kundrát reported that it took three tries (each separated by 10ms) to get a stable clock. Modify behavior to check stable clock ready bit multiple times (20), and waiting 10ms between each try. Note: the first draft of the driver originally used a 50ms delay, without checking the clock stable bit. Then a loop with 1000 retries was implemented, each time reading the clock stable bit. Fixes: 4cf9a888fd3c ("serial: max310x: Check the clock readiness") Cc: stable@vger.kernel.org Suggested-by: Jan Kundrát Link: https://www.spinics.net/lists/linux-serial/msg35773.html Link: https://lore.kernel.org/all/20240110174015.6f20195fde08e5c9e64e5675@hugovil.com/raw Link: https://github.com/boundarydevices/linux/commit/e5dfe3e4a751392515d78051973190301a37ca9a Signed-off-by: Hugo Villeneuve Link: https://lore.kernel.org/r/20240116213001.3691629-3-hugo@hugovil.com Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/max310x.c | 21 ++++++++++++++++----- 1 file changed, 16 insertions(+), 5 deletions(-) --- a/drivers/tty/serial/max310x.c +++ b/drivers/tty/serial/max310x.c @@ -235,6 +235,10 @@ #define MAX310x_REV_MASK (0xf8) #define MAX310X_WRITE_BIT 0x80 +/* Crystal-related definitions */ +#define MAX310X_XTAL_WAIT_RETRIES 20 /* Number of retries */ +#define MAX310X_XTAL_WAIT_DELAY_MS 10 /* Delay between retries */ + /* MAX3107 specific */ #define MAX3107_REV_ID (0xa0) @@ -600,12 +604,19 @@ static int max310x_set_ref_clk(struct de /* Wait for crystal */ if (xtal) { - unsigned int val = 0; - msleep(10); - regmap_read(s->regmap, MAX310X_STS_IRQSTS_REG, &val); - if (!(val & MAX310X_STS_CLKREADY_BIT)) { + bool stable = false; + unsigned int try = 0, val = 0; + + do { + msleep(MAX310X_XTAL_WAIT_DELAY_MS); + regmap_read(s->regmap, MAX310X_STS_IRQSTS_REG, &val); + + if (val & MAX310X_STS_CLKREADY_BIT) + stable = true; + } while (!stable && (++try < MAX310X_XTAL_WAIT_RETRIES)); + + if (!stable) dev_warn(dev, "clock is not stable yet\n"); - } } return (int)bestfreq;