linux-kernel - Re: [PATCH] clk: scmi: Fix the rounding of clock rate

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Message-ID: <CADGdYn5T2-B2UE9DX3wFHdvqfF85n0NAbKDBf2KHOQreRi=H+g@mail.gmail.com>
Date:   Mon, 30 Jul 2018 11:03:51 +0530
From:   Amit Daniel Kachhap <amit.kachhap@....com>
To:     Stephen Boyd <sboyd@...nel.org>
Cc:     LAK <linux-arm-kernel@...ts.infradead.org>,
        Sudeep Holla <sudeep.holla@....com>,
        Michael Turquette <mturquette@...libre.com>,
        linux-clk@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] clk: scmi: Fix the rounding of clock rate

Hi,

On Fri, Jul 27, 2018 at 10:07 PM, Stephen Boyd <sboyd@...nel.org> wrote:
> Quoting Amit Daniel Kachhap (2018-07-27 07:01:52)
>> This fix rounds the clock rate properly by using quotient and not
>> remainder in the calculation. This issue was found while testing HDMI
>> in the Juno platform.
>>
>> Signed-off-by: Amit Daniel Kachhap <amit.kachhap@....com>
>
> Any Fixes: tag here?
Yes, This patch is tested with Linux v4.18-rc6 tag.
>
>> ---
>>  drivers/clk/clk-scmi.c | 5 ++---
>>  1 file changed, 2 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/clk/clk-scmi.c b/drivers/clk/clk-scmi.c
>> index bb2a6f2..a985bf5 100644
>> --- a/drivers/clk/clk-scmi.c
>> +++ b/drivers/clk/clk-scmi.c
>> @@ -60,9 +59,9 @@ static long scmi_clk_round_rate(struct clk_hw *hw, unsigned long rate,
>>
>>         ftmp = rate - fmin;
>>         ftmp += clk->info->range.step_size - 1; /* to round up */
>> -       step = do_div(ftmp, clk->info->range.step_size);
>> +       do_div(ftmp, clk->info->range.step_size);
>>
>> -       return step * clk->info->range.step_size + fmin;
>> +       return ftmp * clk->info->range.step_size + fmin;
>
> Good catch.
Thanks.
>
Regards,
Amit