From mboxrd@z Thu Jan 1 00:00:00 1970 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753568AbeAKWzg (ORCPT + 1 other); Thu, 11 Jan 2018 17:55:36 -0500 Received: from vern.gendns.com ([206.190.152.46]:42886 "EHLO vern.gendns.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750782AbeAKWzd (ORCPT ); Thu, 11 Jan 2018 17:55:33 -0500 Subject: Re: [1/5] clk: divider: read-only divider can propagate rate change To: Jerome Brunet , Stephen Boyd , Michael Turquette , linux-clk@vger.kernel.org Cc: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-arm-msm@vger.kernel.org, Vladimir Zapolskiy , Sylvain Lemieux , Andy Gross , David Brown References: <20180105170959.17266-2-jbrunet@baylibre.com> From: David Lechner Message-ID: <999439aa-276a-575d-d6dc-6e9d1bdf5b15@lechnology.com> Date: Thu, 11 Jan 2018 16:55:31 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.5.0 MIME-Version: 1.0 In-Reply-To: <20180105170959.17266-2-jbrunet@baylibre.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - vern.gendns.com X-AntiAbuse: Original Domain - vger.kernel.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - lechnology.com X-Get-Message-Sender-Via: vern.gendns.com: authenticated_id: davidmain+lechnology.com/only user confirmed/virtual account not confirmed X-Authenticated-Sender: vern.gendns.com: davidmain@lechnology.com X-Source: X-Source-Args: X-Source-Dir: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Return-Path: On 01/05/2018 11:09 AM, Jerome Brunet wrote: > When a divider clock has CLK_DIVIDER_READ_ONLY set, it means that the > register shall be left un-touched, but it does not mean the clock > should stop rate propagation if CLK_SET_RATE_PARENT is set > > This is properly handled in qcom clk-regmap-divider but it was not in > the generic divider > > Fixes: e6d5e7d90be9 ("clk-divider: Fix READ_ONLY when divider > 1") > Signed-off-by: Jerome Brunet > --- > drivers/clk/clk-divider.c | 10 ++++++++++ > 1 file changed, 10 insertions(+) > > diff --git a/drivers/clk/clk-divider.c b/drivers/clk/clk-divider.c > index b49942b9fe50..a851d3e04c7f 100644 > --- a/drivers/clk/clk-divider.c > +++ b/drivers/clk/clk-divider.c > @@ -348,6 +348,7 @@ static long clk_divider_round_rate(struct clk_hw *hw, unsigned long rate, > unsigned long *prate) > { > struct clk_divider *divider = to_clk_divider(hw); > + struct clk_hw *hw_parent = clk_hw_get_parent(hw); Very minor suggestion: This could be moved inside the if block since it is only used there. > int bestdiv; > > /* if read only, just return current value */ > @@ -356,6 +357,15 @@ static long clk_divider_round_rate(struct clk_hw *hw, unsigned long rate, > bestdiv &= div_mask(divider->width); > bestdiv = _get_div(divider->table, bestdiv, divider->flags, > divider->width); > + > + /* Even a read-only clock can propagate a rate change */ > + if (clk_hw_get_flags(hw) & CLK_SET_RATE_PARENT) { > + if (!hw_parent) > + return -EINVAL; > + > + *prate = clk_hw_round_rate(hw_parent, rate * bestdiv); > + } > + > return DIV_ROUND_UP_ULL((u64)*prate, bestdiv); > } > > Tested-by: David Lechner