Re: [RFC PATCH v2 4/6] PM: opp: allow control of multiple clocks

Krzysztof Kozlowski
2022-04-13T09:07:32Z

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.

>
>> + 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.

>
>> +
>> + 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