From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760540AbdEORf1 (ORCPT ); Mon, 15 May 2017 13:35:27 -0400 Received: from anholt.net ([50.246.234.109]:49596 "EHLO anholt.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1760512AbdEORfH (ORCPT ); Mon, 15 May 2017 13:35:07 -0400 From: Eric Anholt To: Lee Jones , Florian Fainelli , Michael Turquette , Stephen Boyd Cc: linux-rpi-kernel@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Stefan Wahren , bcm-kernel-feedback-list@broadcom.com, linux-clk@vger.kernel.org, Phil Elwell , Eric Anholt Subject: [PATCH] clk: bcm2835: Correct the prediv logic Date: Mon, 15 May 2017 10:35:04 -0700 Message-Id: <20170515173504.11337-1-eric@anholt.net> X-Mailer: git-send-email 2.11.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Phil Elwell If a clock has the prediv flag set, both the integer and fractional parts must be scaled when calculating the resulting frequency. Signed-off-by: Phil Elwell Signed-off-by: Eric Anholt --- While this is a bugfix, I haven't put a "Fixes:" line in here to get it automatically backported to stable. We had trouble with the out-of-tree DSI panel driver, at least: Our old set_rate() didn't work, because the new PLL was just barely too fast to get the integer PLL divider we needed. We may run into similar troubles elsewhere. --anholt drivers/clk/bcm/clk-bcm2835.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/clk/bcm/clk-bcm2835.c b/drivers/clk/bcm/clk-bcm2835.c index 025853870619..7a35df6b45bd 100644 --- a/drivers/clk/bcm/clk-bcm2835.c +++ b/drivers/clk/bcm/clk-bcm2835.c @@ -616,8 +616,10 @@ static unsigned long bcm2835_pll_get_rate(struct clk_hw *hw, using_prediv = cprman_read(cprman, data->ana_reg_base + 4) & data->ana->fb_prediv_mask; - if (using_prediv) + if (using_prediv) { ndiv *= 2; + fdiv *= 2; + } return bcm2835_pll_rate_from_divisors(parent_rate, ndiv, fdiv, pdiv); } -- 2.11.0