Re: [PATCH] clk: at91: generated: consider range when calculating best rate

From: <Codrin.Ciubotariu@microchip.com>
To: <sboyd@kernel.org>, <linux-arm-kernel@lists.infradead.org>,
	<linux-clk@vger.kernel.org>, <linux-kernel@vger.kernel.org>
Cc: <mturquette@baylibre.com>, <Nicolas.Ferre@microchip.com>,
	<alexandre.belloni@bootlin.com>, <Claudiu.Beznea@microchip.com>
Subject: Re: [PATCH] clk: at91: generated: consider range when calculating best rate
Date: Tue, 26 Apr 2022 07:24:15 +0000	[thread overview]
Message-ID: <e18eb810-e437-6a19-26ec-1f0daedaaf5f@microchip.com> (raw)
In-Reply-To: <20220422011216.A4A23C385A5@smtp.kernel.org>

On 22.04.2022 04:12, Stephen Boyd wrote:
> Quoting Codrin Ciubotariu (2022-04-13 00:13:18)
>> clk_generated_best_diff() helps in finding the parent and the divisor to
>> compute a rate closest to the required one. However, it doesn't take into
>> account the request's range for the new rate. Make sure the new rate
>> is within the required range.
>>
>> Fixes: 8a8f4bf0c480 ("clk: at91: clk-generated: create function to find best_diff")
>> Signed-off-by: Codrin Ciubotariu <codrin.ciubotariu@microchip.com>
>> ---
> 
> Is this fixing anything real or it's just a thing that you noticed and
> sent a patch to fix?

It fixes the clk_set_min/max_rate() calls to a generated clock. Do you 
want me to add this fact in the commit description?

> 
>>   drivers/clk/at91/clk-generated.c | 4 ++++
>>   1 file changed, 4 insertions(+)
>>
>> diff --git a/drivers/clk/at91/clk-generated.c b/drivers/clk/at91/clk-generated.c
>> index 23cc8297ec4c..d429ba52a719 100644
>> --- a/drivers/clk/at91/clk-generated.c
>> +++ b/drivers/clk/at91/clk-generated.c
>> @@ -117,6 +117,10 @@ static void clk_generated_best_diff(struct clk_rate_request *req,
>>                  tmp_rate = parent_rate;
>>          else
>>                  tmp_rate = parent_rate / div;
>> +
>> +       if (tmp_rate < req->min_rate || tmp_rate > req->max_rate)
>> +               return;
>> +
>>          tmp_diff = abs(req->rate - tmp_rate);
>>
>>          if (*best_diff < 0 || *best_diff >= tmp_diff) {