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Date:   Tue, 19 Apr 2022 20:06:28 -0700
From:   Bjorn Andersson <bjorn.andersson@linaro.org>
To:     Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Cc:     Andy Gross <agross@kernel.org>,
        Michael Turquette <mturquette@baylibre.com>,
        Stephen Boyd <sboyd@kernel.org>,
        Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Viresh Kumar <vireshk@kernel.org>, Nishanth Menon <nm@ti.com>,
        Alim Akhtar <alim.akhtar@samsung.com>,
        Avri Altman <avri.altman@wdc.com>,
        "James E.J. Bottomley" <jejb@linux.ibm.com>,
        "Martin K. Petersen" <martin.petersen@oracle.com>,
        "Rafael J. Wysocki" <rafael@kernel.org>,
        Taniya Das <tdas@codeaurora.org>,
        linux-arm-msm@vger.kernel.org, linux-clk@vger.kernel.org,
        devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-pm@vger.kernel.org, linux-scsi@vger.kernel.org
Subject: Re: [RFC PATCH v2 4/6] PM: opp: allow control of multiple clocks
Message-ID: <Yl94tB+FrZu/am0/@ripper>
References: <20220411154347.491396-1-krzysztof.kozlowski@linaro.org>
 <20220411154347.491396-5-krzysztof.kozlowski@linaro.org>
 <YlWztZknl4OBmekp@ripper>
 <02fc797a-190f-3558-5ee1-c9c3320f3d57@linaro.org>
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In-Reply-To: <02fc797a-190f-3558-5ee1-c9c3320f3d57@linaro.org>
Precedence: bulk

On Wed 13 Apr 02:07 PDT 2022, Krzysztof Kozlowski wrote:

> On 12/04/2022 19:15, Bjorn Andersson wrote:
> >>  
> >> +	opp_table->clks = kmalloc_array(1, sizeof(*opp_table->clks),
> >> +					GFP_KERNEL);
> > 
> > This seems to be 81 chars long, perhaps worth not line breaking?
> 
> I doubt that it will increase the readability:
> 
> 	opp_table->clks = kmalloc_array(1,
> 					sizeof(*opp_table->clks),
> 					GFP_KERNEL);
> 
> 80-character is not anymore that strict hard limit and in such case
> using 1-2 characters longer improves the code.
> 

I was suggesting that you remove the line break

	opp_table->clks = kmalloc_array(1, sizeof(*opp_table->clks), GFP_KERNEL);

Seems to be 81 chars long, which is fine in my book with or without the
80-char guideline.

> > 
> >> +	if (!opp_table->clks)
> >> +		return ERR_PTR(-ENOMEM);
> >> +
> >>  	/* Find clk for the device */
> >> -	opp_table->clk = clk_get(dev, NULL);
> >> +	opp_table->clks[0] = clk_get(dev, NULL);
> >>  
> >> -	ret = PTR_ERR_OR_ZERO(opp_table->clk);
> >> -	if (!ret)
> >> +	ret = PTR_ERR_OR_ZERO(opp_table->clks[0]);
> >> +	if (!ret) {
> >> +		opp_table->clk_count = 1;
> >>  		return opp_table;
> >> +	}
> > [..]
> >> +struct opp_table *dev_pm_opp_set_clknames(struct device *dev,
> >> +					  const char * const names[],
> >> +					  unsigned int count)
> >>  {
> >>  	struct opp_table *opp_table;
> >> -	int ret;
> >> +	struct clk *clk;
> >> +	int ret, i;
> >>  
> >>  	opp_table = _add_opp_table(dev, false);
> >>  	if (IS_ERR(opp_table))
> >> @@ -2159,70 +2259,92 @@ struct opp_table *dev_pm_opp_set_clkname(struct device *dev, const char *name)
> >>  	}
> >>  
> >>  	/* clk shouldn't be initialized at this point */
> >> -	if (WARN_ON(opp_table->clk)) {
> >> +	if (WARN_ON(opp_table->clks)) {
> >>  		ret = -EBUSY;
> >>  		goto err;
> >>  	}
> >>  
> >> -	/* Find clk for the device */
> >> -	opp_table->clk = clk_get(dev, name);
> >> -	if (IS_ERR(opp_table->clk)) {
> >> -		ret = dev_err_probe(dev, PTR_ERR(opp_table->clk),
> >> -				    "%s: Couldn't find clock\n", __func__);
> >> +	opp_table->clks = kmalloc_array(count, sizeof(*opp_table->clks),
> >> +					GFP_KERNEL);
> >> +	if (!opp_table->clks) {
> >> +		ret = -ENOMEM;
> >>  		goto err;
> >>  	}
> >>  
> >> +	for (i = 0; i < count; i++) {
> >> +		clk = clk_get(dev, names[i]);
> >> +		if (IS_ERR(clk)) {
> >> +			ret =  dev_err_probe(dev, PTR_ERR(clk),
> >> +					     "%s: Couldn't find clock %s\n",
> >> +					     __func__, names[i]);
> >> +			goto free_clks;
> >> +		}
> >> +
> >> +		opp_table->clks[i] = clk;
> >> +	}
> > 
> > Wouldn't it be convenient to make clks a struct clk_bulk_data array
> > and use clk_bulk_get()/clk_bulk_put() instead?
> 
> I was thinking about this but clk_bulk_get() requires struct
> clk_bulk_data, so the code in "get" is not actually smaller if function
> receives array of clock names.
> 
> OTOH, usage of clk_bulk_get() would reduce code in: _put_clocks(). Rest
> of the code would be more-or-less the same, including all corner cases
> when clocks are missing.
> 

Fair enough, I think you're right that it's not going to be much
difference.

Regards,
Bjorn


> > 
> >> +
> >> +	opp_table->clk_count = count;
> >> +
> >>  	return opp_table;
> >>  
> >> +free_clks:
> >> +	while (i != 0)
> >> +		clk_put(opp_table->clks[--i]);
> >> +
> >> +	kfree(opp_table->clks);
> >> +	opp_table->clks = NULL;
> >> +	opp_table->clk_count = -1;
> >>  err:
> >>  	dev_pm_opp_put_opp_table(opp_table);
> >>  
> >>  	return ERR_PTR(ret);
> >>  }
> >> -EXPORT_SYMBOL_GPL(dev_pm_opp_set_clkname);
> >> +EXPORT_SYMBOL_GPL(dev_pm_opp_set_clknames);
> > [..]
> >> +static int _read_clocks(struct dev_pm_opp *opp, struct opp_table *opp_table,
> >> +			struct device_node *np)
> >> +{
> >> +	int count, ret;
> >> +	u64 *freq;
> >> +
> >> +	count = of_property_count_u64_elems(np, "opp-hz");
> >> +	if (count < 0) {
> >> +		pr_err("%s: Invalid %s property (%d)\n",
> >> +			__func__, of_node_full_name(np), count);
> > 
> > Wouldn't %pOF be convenient to use here, seems like it becomes short
> > enough that you don't have to wrap this line then.
> 
> Yes, I forgot about %pOF.
> 
> > 
> >> +		return count;
> >> +	}
> >> +
> >> +	if (count != opp_table->clk_count) {
> >> +		pr_err("%s: number of rates %d does not match number of clocks %d in %s\n",
> >> +		       __func__, count, opp_table->clk_count,
> >> +		       of_node_full_name(np));
> >> +		return -EINVAL;
> >> +	}
> >> +
> >> +	freq = kmalloc_array(count, sizeof(*freq), GFP_KERNEL);
> >> +	if (!freq)
> >> +		return -ENOMEM;
> >> +
> >> +	ret = of_property_read_u64_array(np, "opp-hz", freq, count);
> >> +	if (ret) {
> >> +		pr_err("%s: error parsing %s: %d\n", __func__,
> >> +		       of_node_full_name(np), ret);
> >> +		ret = -EINVAL;
> >> +		goto free_freq;
> >> +	}
> > 
> > Regards,
> > Bjorn
> 
> 
> Best regards,
> Krzysztof