From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751310AbdE3Q2C (ORCPT ); Tue, 30 May 2017 12:28:02 -0400 Received: from mx07-00252a01.pphosted.com ([62.209.51.214]:38787 "EHLO mx07-00252a01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751034AbdE3Q17 (ORCPT ); Tue, 30 May 2017 12:27:59 -0400 To: Michael Turquette , Stephen Boyd , Eric Anholt , Stefan Wahren , Florian Fainelli , linux-clk@vger.kernel.org, linux-rpi-kernel@lists.infradead.org, linux-kernel@vger.kernel.org From: Phil Elwell Subject: [PATCH 0/2] clk: bcm2835: PCM clock improvements Message-ID: <4c11ad43-ef4e-3fbd-500a-02b2b46e0fbd@raspberrypi.org> Date: Tue, 30 May 2017 17:27:56 +0100 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.1.1 MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Language: en-GB Content-Transfer-Encoding: 7bit X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2017-05-30_10:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_spam_notspam policy=outbound_spam score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 impostorscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1703280000 definitions=main-1705300305 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The switch to using the upstream bcm2835_cprman clock driver caused a few problems for users of PCM (I2S) peripherals. Audio applications require accurate, stable clocks, and the cprman driver wasn't conservative enough in its choice of clock sources. These patches restrict the clock sources for the PCM peripheral in two ways: the first causes all possible sources except OSC and PLLD_PER to be ignored, while the second allows clocks to be specified as "low_jitter", causing the effects of fractional divisors to be taken into account when comparing potential clocks for accuracy. In practice, the combined effect of the two patches is to choose OSC as a source if an integer divisor can be used, otherwise PLLD_PER is chosen. Phil Elwell (2): clk: bcm2835: Limit PCM clock to OSC and PLLD_PER clk: bcm2835: Minimise clock jitter for PCM clock drivers/clk/bcm/clk-bcm2835.c | 50 ++++++++++++++++++++++++++++++++++++++----- 1 file changed, 45 insertions(+), 5 deletions(-) -- 1.9.1