linux-kernel - Re: [PATCH v5 02/44] clk: davinci: New driver for davinci PLL clocks

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Date:   Tue, 16 Jan 2018 12:02:47 +0530
From:   Sekhar Nori <nsekhar@...com>
To:     David Lechner <david@...hnology.com>, <linux-clk@...r.kernel.org>,
        <devicetree@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>
CC:     Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...eaurora.org>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Kevin Hilman <khilman@...nel.org>,
        Adam Ford <aford173@...il.com>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v5 02/44] clk: davinci: New driver for davinci PLL clocks

On Saturday 13 January 2018 07:43 AM, David Lechner wrote:
> On 01/12/2018 03:21 AM, Sekhar Nori wrote:
>> On Monday 08 January 2018 07:47 AM, David Lechner wrote:
>>> +static unsigned long davinci_pll_clk_recalc(struct clk_hw *hw,
>>> +                        unsigned long parent_rate)
>>> +{
>>> +    struct davinci_pll_clk *pll = to_davinci_pll_clk(hw);
>>> +    unsigned long rate = parent_rate;
>>> +    u32 prediv, mult, postdiv;
>>> +
>>> +    prediv = readl(pll->base + PREDIV) & PREDIV_RATIO_MASK;
>>> +    mult = readl(pll->base + PLLM) & PLLM_MASK;
>>> +    postdiv = readl(pll->base + POSTDIV) & POSTDIV_RATIO_MASK;
>>
>> Shouldn't we check if the pre and post dividers are enabled before using
>> them?
> 
> I dug into this and the answer is no. The enable bit acts like a gate, not
> a bypass, so it does not affect the rate calculation.

Alright, thanks for checking this.

Regards,
Sekhar