linux-kernel - Re: [PATCH v1] clk: keystone: sci-clk: Adding support for non contiguous clocks

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Message-ID: <5a17f3dd-a27a-49d3-9e54-a0022333abe2@ti.com>
Date: Mon, 5 Feb 2024 23:13:27 +0530
From: "Kumar, Udit" <u-kumar1@...com>
To: Nishanth Menon <nm@...com>
CC: <kristo@...nel.org>, <ssantosh@...nel.org>, <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 v1] clk: keystone: sci-clk: Adding support for non
 contiguous clocks


On 2/5/2024 7:34 PM, Nishanth Menon wrote:
> On 10:15-20240205, 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 assigns
>> accordingly.
>>
>> New firmware started returning error in case of
>> non-available clock id.  Therefore drivers throws error while
>> re-calculate and other functions.
> What changed here? started returning error for what API? also please fix
> up 70 char alignment -> there extra spaces in your commit message.


will address in v2

>> In this fix, before assigning and adding clock in list,
>> driver checks if given clock is valid or not.
>>
>> 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 and 18-19 not present
>>
>> Signed-off-by: Udit Kumar <u-kumar1@...com>
>> ---
>> Original logs
>> https://gist.github.com/uditkumarti/de4b36b21247fb36725ad909ce4812f6#file-original-logs
>> Line 2630 for error
>>
>> Logs with fix
>> https://gist.github.com/uditkumarti/de4b36b21247fb36725ad909ce4812f6#file-with-fix
>> Line 2594
>>
>>   drivers/clk/keystone/sci-clk.c | 20 ++++++++++++++++----
>>   1 file changed, 16 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/clk/keystone/sci-clk.c b/drivers/clk/keystone/sci-clk.c
>> index 35fe197dd303..d417ec018d82 100644
>> --- a/drivers/clk/keystone/sci-clk.c
>> +++ b/drivers/clk/keystone/sci-clk.c
>> @@ -517,6 +517,8 @@ static int ti_sci_scan_clocks_from_dt(struct sci_clk_provider *provider)
>>   	int num_clks = 0;
>>   	int num_parents;
>> [..]
>> -					num_clks++;
>> +						ret = provider->ops->get_freq(provider->sci,
>> +							   sci_clk->dev_id, sci_clk->clk_id, &freq);
>> +					} while (ret != 0 && clk_id < max_clk_id);
> take clock ids 0 1 2 3 -> Say 2 is reserved.
> num_parents = 4
> while(num_parents) Loop 1 ->  clk ID 0 is valid, list_add_tail
> while(num_parents) Loop 2 ->  clk ID 1 is valid, list_add_tail
> while(num_parents) Loop 3 ->  clk ID 2 is invalid.. so we scan forward
> 	to clk ID 3 -> list_add_tail
> while(num_parents) Loop 4 ->  clk ID 4 is invalid.. but 5 is out of
> 	range, so we break off loop. sci_clk is still devm_kzalloced ->
> 	but since clk_id > max_clk_id, we jump off loop, and we dont add
> 	it to tail. so one extra allocation?

Thanks for catching this.


> If we have multiple reserved intermediate ones, then we'd have as many
> allocations that aren't linked? Could we not improve the logic a bit to
> allocate just what is necessary?

Sure, will change in v2.

to check clock validity first and then allocate, add


>> +
>> +					sci_clk->provider = provider;
>> +					if (ret == 0) {
>> +						list_add_tail(&sci_clk->node, &clks);
>> +						num_clks++;
>> +					}
>>   				}
>>   			}
>>   
>> -- 
>> 2.34.1
>>