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

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Message-ID: <a0249265-255b-40d7-b609-c1ab6a789d46@ti.com>
Date: Tue, 6 Feb 2024 19:44:51 +0530
From: "Kumar, Udit" <u-kumar1@...com>
To: Nishanth Menon <nm@...com>
CC: <kristo@...nel.org>, <ssantosh@...nel.org>, <chandru@...com>,
        <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>
Subject: Re: [PATCH v2] clk: keystone: sci-clk: Adding support for non
 contiguous clocks


On 2/6/2024 6:44 PM, Nishanth Menon wrote:
> 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>
>> ---
>> Changelog
>>
>> Changes in v2
>> - Updated commit message
>> - Simplified logic for valid clock id
>> link to v1 https://lore.kernel.org/all/20240205044557.3340848-1-u-kumar1@ti.com/
>>
>>
>> P.S
>> Firmawre returns total num_parents count including non available ids.
>> For above device id NAVSS0_CPTS_0, number of parents clocks are 16
>> i.e from id 2 to 17. But out of these ids few are not valid.
>> So driver adds only valid clock ids out ot total.
>>
>> Original logs
>> https://gist.github.com/uditkumarti/de4b36b21247fb36725ad909ce4812f6#file-original-logs
>> Line 2630 for error
>>
>> Logs with fix v2
>> https://gist.github.com/uditkumarti/94e3e28d62282fd708dbfe37435ce1d9
>> Line 2591
>>
>>
>>   drivers/clk/keystone/sci-clk.c | 12 ++++++++++--
>>   1 file changed, 10 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/clk/keystone/sci-clk.c b/drivers/clk/keystone/sci-clk.c
>> index 35fe197dd303..ff249cbd54a1 100644
>> --- a/drivers/clk/keystone/sci-clk.c
>> +++ b/drivers/clk/keystone/sci-clk.c
>> @@ -517,6 +517,7 @@ static int ti_sci_scan_clocks_from_dt(struct sci_clk_provider *provider)
>>   	int num_clks = 0;
>>   	int num_parents;
>>   	int clk_id;
>> +	u64 freq;
>>   	const char * const clk_names[] = {
>>   		"clocks", "assigned-clocks", "assigned-clock-parents", NULL
>>   	};
>> @@ -586,16 +587,23 @@ static int ti_sci_scan_clocks_from_dt(struct sci_clk_provider *provider)
>>   				clk_id = args.args[1] + 1;
>>   
>>   				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?


Let me check , if we have some other alternative here

>> +
>> +					clk_id++;
>> +					if (ret)
>> +						continue;
>> +
>>   					sci_clk = devm_kzalloc(dev,
>>   							       sizeof(*sci_clk),
>>   							       GFP_KERNEL);
>>   					if (!sci_clk)
>>   						return -ENOMEM;
>>   					sci_clk->dev_id = args.args[0];
>> -					sci_clk->clk_id = clk_id++;
>> +					sci_clk->clk_id = clk_id - 1;
>>   					sci_clk->provider = provider;
>>   					list_add_tail(&sci_clk->node, &clks);
>> -
> 	Spurious change.

I think, you meant by deleting the line ?

If yes then will address in next version


>>   					num_clks++;
>>   				}
>>   			}
>> -- 
>> 2.34.1
>>