linux-kernel - Re: [PATCH v2] clk: keystone: sci-clk: Adding support for non contiguous clocks

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Date: Tue, 6 Feb 2024 20:09:05 +0530
From: "Kumar, Udit" <u-kumar1@...com>
To: CHANDRU DHAVAMANI <chandru@...com>, Kamlesh Gurudasani <kamlesh@...com>,
        Nishanth Menon <nm@...com>
CC: <kristo@...nel.org>, <ssantosh@...nel.org>, <rishabh@...com>,
        <vigneshr@...com>, <mturquette@...libre.com>, <sboyd@...nel.org>,
        <linux-arm-kernel@...ts.infradead.org>, <linux-kernel@...r.kernel.org>,
        <linux-clk@...r.kernel.org>, <u-kumar1@...com>
Subject: Re: [PATCH v2] clk: keystone: sci-clk: Adding support for non
 contiguous clocks


On 2/6/2024 7:56 PM, CHANDRU DHAVAMANI wrote:
>
> On 06/02/24 19:45, Kumar, Udit wrote:
>>
>> On 2/6/2024 7:24 PM, Kamlesh Gurudasani wrote:
>>> Nishanth Menon <nm@...com> writes:
>>>
>>>> On 16:13-20240206, Udit Kumar wrote:
>>>>> Most of clocks and their parents are defined in contiguous range,
>>>>> But in few cases, there is gap in clock numbers[0].
>>>>> Driver assumes clocks to be in contiguous range, and add their clock
>>>>> ids incrementally.
>>>>>
>>>>> New firmware started returning error while calling get_freq and is_on
>>>>> API for non-available clock ids.
>>>>>
>>>>> In this fix, driver checks and adds only valid clock ids.
>>>>>
>>>>> Fixes: 3c13933c6033 ("clk: keystone: sci-clk: add support for 
>>>>> dynamically probing clocks")
>>>>>
>>>>> [0] 
>>>>> https://software-dl.ti.com/tisci/esd/latest/5_soc_doc/j7200/clocks.html 
>>>>>
>>>>> Section Clocks for NAVSS0_CPTS_0 Device,
>>>>> clock id 12-15 not present.
>>>>>
>>>>> Signed-off-by: Udit Kumar <u-kumar1@...com>
>>>>>                   while (num_parents--) {
>>>>> +                    /* Check if this clock id is valid */
>>>>> +                    ret = provider->ops->get_freq(provider->sci,
>>>>> +                        sci_clk->dev_id, clk_id, &freq);
>>>> get_freq is a bit expensive as it has to walk the clock tree to find
>>>> the clock frequency (at least the first time?). just wondering if
>>>> there is lighter alternative here?
>>>>
>>> How about get_clock? Doesn't read the registers at least.
>>
>> Said API needs, some flags to be passed,
>>
>> Can those flag be set to zero, Chandru ?
>
>
> get_clock doesn't require any flags to be passed.


May be firmware does not need it but  I was referring to

https://elixir.bootlin.com/linux/latest/source/drivers/clk/keystone/sci-clk.c#L78



>
>
>>
>>
>>> Regards,
>>> Kamlesh