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Date:	Thu, 10 Jul 2014 12:51:56 +0200
From:	Tomeu Vizoso <tomeu.vizoso@...labora.com>
To:	Tomasz Figa <tomasz.figa@...il.com>,
	Stephen Warren <swarren@...dotorg.org>,
	Thierry Reding <thierry.reding@...il.com>,
	Mike Turquette <mturquette@...aro.org>, rabin@....in,
	linux-tegra@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org
CC:	Rabin Vincent <rabin.vincent@...ricsson.com>,
	Javier Martinez Canillas <javier.martinez@...labora.co.uk>
Subject: Re: [RFC v2 4/5] clk: per-user clock accounting for debug

On 07/09/2014 10:01 PM, Tomasz Figa wrote:
> Hi Tomeu, Rabin,
>
> Please see my comments inline.
>
> On 03.07.2014 16:38, Tomeu Vizoso wrote:
>> From: Rabin Vincent <rabin.vincent@...ricsson.com>
>>
>> When a clock has multiple users, the WARNING on imbalance of
>> enable/disable may not show the guilty party since although they may
>> have commited the error earlier, the warning is emitted later when some
>> other user, presumably innocent, disables the clock.
>
> [snip]
>
>> diff --git a/drivers/clk/clk-devres.c b/drivers/clk/clk-devres.c
>> index 5f2aba9..d6a5e59 100644
>> --- a/drivers/clk/clk-devres.c
>> +++ b/drivers/clk/clk-devres.c
>> @@ -37,7 +37,8 @@ EXPORT_SYMBOL(devm_clk_provider_get);
>>
>>   struct clk *devm_clk_get(struct device *dev, const char *id)
>>   {
>> -	return clk_core_to_clk(devm_clk_provider_get(dev, id));
>> +	const char *dev_id = dev ? dev_name(dev) : NULL;
>> +	return clk_core_to_clk(devm_clk_provider_get(dev, id), dev_id, id);
>
> Hmm, correct me if I'm missing something but you're just calling
> devm_clk_provider() which guarantees calling of clk_provider_put() on
> device removal, but what about the consumer struct being created here?
>
> Shouldn't you rather call normal clk_provider_get() here, then create a
> consumer struct for it and then wrap it up using devres, providing
> appropriate release function?

You are totally right.

>>   }
>>   EXPORT_SYMBOL(devm_clk_get);
>>
>> diff --git a/drivers/clk/clk-highbank.c b/drivers/clk/clk-highbank.c
>> index cc1bae1..4e38856 100644
>> --- a/drivers/clk/clk-highbank.c
>> +++ b/drivers/clk/clk-highbank.c
>> @@ -331,7 +331,7 @@ CLK_OF_DECLARE(hb_a9periph, "calxeda,hb-a9periph-clock", hb_a9periph_init);
>>   static void __init hb_a9bus_init(struct device_node *node)
>>   {
>>   	struct clk_core *clk = hb_clk_init(node, &a9bclk_ops);
>> -	clk_prepare_enable(clk_core_to_clk(clk));
>> +	clk_prepare_enable(clk_core_to_clk(clk, node->full_name, NULL));
>>   }
>>   CLK_OF_DECLARE(hb_a9bus, "calxeda,hb-a9bus-clock", hb_a9bus_init);
>>
>> diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
>> index 644a824..b887c69 100644
>> --- a/drivers/clk/clk.c
>> +++ b/drivers/clk/clk.c
>> @@ -568,6 +568,28 @@ static int clk_disable_unused(void)
>>   }
>>   late_initcall_sync(clk_disable_unused);
>>
>> +struct clk *clk_core_to_clk(struct clk_core *clk_core, const char *dev,
>> +			    const char *con)
>
> Name of this function suggests that this is just a simple conversion,
> while it creates new object. I would suggest calling this
> clk_create_consumer() or something along these lines.

Agreed, that sounds better.

>> +{
>> +	struct clk *clk;
>> +
>> +	clk = kzalloc(sizeof(*clk), GFP_KERNEL);
>> +	if (!clk)
>> +		return ERR_PTR(-ENOMEM);
>
> [snip]
>
>> +static void clk_free_clk(struct clk *clk)
>> +{
>> +	kfree(clk);
>> +}
>
> Any need for this one-liner? Seems to be used just once below.

Yeah, should probably remove it from this patch and only reintroduce it 
later when it's actually needed.

>> +
>>   void clk_put(struct clk *clk)
>>   {
>> -	__clk_put(clk_to_clk_core(clk));
>> +	clk_core_t *core = clk_to_clk_core(clk);
>> +
>> +	clk_free_clk(clk);
>> +	__clk_put(core);
>>   }
>>   EXPORT_SYMBOL(clk_put);
>>
>> diff --git a/drivers/clk/qcom/mmcc-msm8960.c b/drivers/clk/qcom/mmcc-msm8960.c
>> index 28a5d30..47f21ea 100644
>> --- a/drivers/clk/qcom/mmcc-msm8960.c
>> +++ b/drivers/clk/qcom/mmcc-msm8960.c
>> @@ -470,7 +470,8 @@ static int pix_rdi_set_parent(struct clk_hw *hw, u8 index)
>>   	 * needs to be on at what time.
>>   	 */
>>   	for (i = 0; i < num_parents; i++) {
>> -		ret = clk_prepare_enable(clk_core_to_clk(clk_get_parent_by_index(clk, i)));
>> +		struct clk_core *parent = clk_get_parent_by_index(clk, i);
>> +		ret = clk_prepare_enable(clk_core_to_clk(parent, NULL, __clk_get_name(parent)));
>
> Shouldn't this use clk_provider_*() instead? IMHO clk_core_to_clk() and
> clk_to_clk_core() shouldn't be available to clock drivers, just the core
> clock code. Consumers should operate on struct clks alone, clock drivers
> should operate only on struct clk_cores and only the core code should be
> responsible for necessary conversions.

Totally, this is already fixed in my local version.

>>   		if (ret)
>>   			goto err;
>>   	}
>> @@ -498,8 +499,10 @@ static int pix_rdi_set_parent(struct clk_hw *hw, u8 index)
>>   	udelay(1);
>>
>>   err:
>> -	for (i--; i >= 0; i--)
>> -		clk_disable_unprepare(clk_core_to_clk(clk_get_parent_by_index(clk, i)));
>> +	for (i--; i >= 0; i--) {
>> +		struct clk_core *parent = clk_get_parent_by_index(clk, i);
>> +		clk_disable_unprepare(clk_core_to_clk(parent, NULL, __clk_get_name(parent)));
>
> Hmm. Memory leak? Every time this operation is called you create a
> consumer struct for each parent two times.

Yes, fortunately this won't be needed as we'll have 
clk_provider_disable_unprepare and friends.

>> +	}
>>
>>   	return ret;
>>   }
>> diff --git a/drivers/clk/sunxi/clk-sunxi.c b/drivers/clk/sunxi/clk-sunxi.c
>> index 5de44c1..550a691 100644
>> --- a/drivers/clk/sunxi/clk-sunxi.c
>> +++ b/drivers/clk/sunxi/clk-sunxi.c
>> @@ -1196,7 +1196,7 @@ static void __init sunxi_init_clocks(const char *clocks[], int nclocks)
>>   		struct clk_core *clk = clk_provider_get(NULL, clocks[i]);
>>
>>   		if (!IS_ERR(clk))
>> -			clk_prepare_enable(clk_core_to_clk(clk));
>> +			clk_prepare_enable(clk_core_to_clk(clk, NULL, clocks[i]));
>
> Probably should use clk_provider_*()?
>
>>   	}
>>   }
>>
>> diff --git a/drivers/clk/tegra/clk.c b/drivers/clk/tegra/clk.c
>> index 385d101..2a03d47 100644
>> --- a/drivers/clk/tegra/clk.c
>> +++ b/drivers/clk/tegra/clk.c
>> @@ -228,7 +228,7 @@ void __init tegra_init_from_table(struct tegra_clk_init_table *tbl,
>>   			}
>>
>>   		if (tbl->state)
>> -			if (clk_prepare_enable(clk_core_to_clk(clk))) {
>> +			if (clk_prepare_enable(clk_core_to_clk(clk, NULL, __clk_get_name(clk)))) {
>
> Ditto. And all similar cases below which I skipped due to lack of any
> added value to this review.
>
>>   				pr_err("%s: Failed to enable %s\n", __func__,
>>   				       __clk_get_name(clk));
>>   				WARN_ON(1);
>
> [snip]
>
>> diff --git a/include/linux/clk-private.h b/include/linux/clk-private.h
>> index 2c1ece9..9657fc8 100644
>> --- a/include/linux/clk-private.h
>> +++ b/include/linux/clk-private.h
>> @@ -57,6 +57,10 @@ struct clk_core {
>>
>>   struct clk {
>>   	struct clk_core	*core;
>> +	unsigned int	enable_count;
>> +	const char	*dev_id;
>> +	const char	*con_id;
>> +	void		*last_disable;
>
> Probably the same as for enables should be done for prepares.

Yes, I think it would be useful as well.

>>   };
>>
>>   /*
>> diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h
>> index 87de32c..abfc31a 100644
>> --- a/include/linux/clk-provider.h
>> +++ b/include/linux/clk-provider.h
>> @@ -533,7 +533,8 @@ struct clk_core *clk_provider_get_sys(const char *dev_id, const char *con_id);
>>   struct clk_core *clk_provider_get(struct device *dev, const char *con_id);
>>   struct clk_core *devm_clk_provider_get(struct device *dev, const char *id);
>>
>> -#define clk_core_to_clk(core)	((struct clk *)(core))
>
> Btw. this should have been a static inline.

Agreed.

Thanks,

Tomeu

> Best regards,
> Tomasz
>

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