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

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Message-ID: <87wmrhy8qb.fsf@kamlesh.i-did-not-set--mail-host-address--so-tickle-me>
Date: Tue, 6 Feb 2024 19:51:00 +0530
From: Kamlesh Gurudasani <kamlesh@...com>
To: Udit Kumar <u-kumar1@...com>, <nm@...com>, <kristo@...nel.org>,
        <ssantosh@...nel.org>, <chandru@...com>, <rishabh@...com>
CC: <vigneshr@...com>, <mturquette@...libre.com>, <sboyd@...nel.org>,
        <linux-arm-kernel@...ts.infradead.org>, <linux-kernel@...r.kernel.org>,
        <linux-clk@...r.kernel.org>, Udit Kumar <u-kumar1@...com>
Subject: Re: [PATCH v2] clk: keystone: sci-clk: Adding support for non
 contiguous clocks

Udit Kumar <u-kumar1@...com> writes:

> 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>
..
> @@ -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);


> +
> +					clk_id++;
Why increment it here and subtract if get_freq succeeds (sci_clk->clk_id = clk_id - 1;), rather
if(ret) {
        clk_id++;
        continue;
}
> +					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;
and keep sci_clk->clk_id = clk_id++; intact

saves one subtraction

or even better

 - 				clk_id = args.args[1] + 1;
 + 				clk_id = args.args[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);

and then no increments after, for clk_id

Regards,
Kamlesh