Re: [PATCH v6 2/3] OPP: Add support for bandwidth OPP tables

From: Viresh Kumar <viresh.kumar@linaro.org>
To: Saravana Kannan <saravanak@google.com>
Cc: Rob Herring <robh+dt@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Viresh Kumar <vireshk@kernel.org>, Nishanth Menon <nm@ti.com>,
	Stephen Boyd <sboyd@kernel.org>,
	"Rafael J. Wysocki" <rjw@rjwysocki.net>,
	Georgi Djakov <georgi.djakov@linaro.org>,
	vincent.guittot@linaro.org, seansw@qti.qualcomm.com,
	daidavid1@codeaurora.org, adharmap@codeaurora.org,
	Rajendra Nayak <rnayak@codeaurora.org>,
	sibis@codeaurora.org, bjorn.andersson@linaro.org,
	evgreen@chromium.org, kernel-team@android.com,
	linux-pm@vger.kernel.org, devicetree@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH v6 2/3] OPP: Add support for bandwidth OPP tables
Date: Wed, 8 Jan 2020 16:23:48 +0530	[thread overview]
Message-ID: <20200108105348.p4y3s2mbuchiu4mf@vireshk-i7> (raw)
In-Reply-To: <20191207002424.201796-3-saravanak@google.com>

On 06-12-19, 16:24, Saravana Kannan wrote:
> Not all devices quantify their performance points in terms of frequency.
> Devices like interconnects quantify their performance points in terms of
> bandwidth. We need a way to represent these bandwidth levels in OPP. So,
> add support for parsing bandwidth OPPs from DT.
> 
> Signed-off-by: Saravana Kannan <saravanak@google.com>
> ---
>  drivers/opp/core.c | 15 +++++++++--
>  drivers/opp/of.c   | 63 ++++++++++++++++++++++++++++++++--------------
>  drivers/opp/opp.h  |  5 ++++
>  3 files changed, 62 insertions(+), 21 deletions(-)
> 
> diff --git a/drivers/opp/core.c b/drivers/opp/core.c
> index be7a7d332332..c79bbfac7289 100644
> --- a/drivers/opp/core.c
> +++ b/drivers/opp/core.c
> @@ -1282,11 +1282,21 @@ static bool _opp_supported_by_regulators(struct dev_pm_opp *opp,
>  	return true;
>  }
>  
> +int opp_compare_key(struct dev_pm_opp *opp1, struct dev_pm_opp *opp2)
> +{
> +	if (opp1->rate != opp2->rate)
> +		return opp1->rate < opp2->rate ? -1 : 1;
> +	if (opp1->peak_bw != opp2->peak_bw)
> +		return opp1->peak_bw < opp2->peak_bw ? -1 : 1;

Please also add level here.

> +	return 0;
> +}
> +
>  static int _opp_is_duplicate(struct device *dev, struct dev_pm_opp *new_opp,
>  			     struct opp_table *opp_table,
>  			     struct list_head **head)
>  {
>  	struct dev_pm_opp *opp;
> +	int opp_cmp;
>  
>  	/*
>  	 * Insert new OPP in order of increasing frequency and discard if
> @@ -1297,12 +1307,13 @@ static int _opp_is_duplicate(struct device *dev, struct dev_pm_opp *new_opp,
>  	 * loop.
>  	 */
>  	list_for_each_entry(opp, &opp_table->opp_list, node) {
> -		if (new_opp->rate > opp->rate) {
> +		opp_cmp = opp_compare_key(new_opp, opp);
> +		if (opp_cmp > 0) {
>  			*head = &opp->node;
>  			continue;
>  		}
>  
> -		if (new_opp->rate < opp->rate)
> +		if (opp_cmp < 0)
>  			return 0;
>  
>  		/* Duplicate OPPs */
> diff --git a/drivers/opp/of.c b/drivers/opp/of.c
> index 1cbb58240b80..b565da5a2b1f 100644
> --- a/drivers/opp/of.c
> +++ b/drivers/opp/of.c
> @@ -521,6 +521,44 @@ void dev_pm_opp_of_remove_table(struct device *dev)
>  }
>  EXPORT_SYMBOL_GPL(dev_pm_opp_of_remove_table);
>  
> +static int _read_opp_key(struct dev_pm_opp *new_opp, struct device_node *np,
> +			 bool *rate_not_available)
> +{
> +	int ret;
> +	u64 rate;
> +	u32 bw;
> +
> +	ret = of_property_read_u64(np, "opp-hz", &rate);
> +	if (!ret) {
> +		/*
> +		 * Rate is defined as an unsigned long in clk API, and so
> +		 * casting explicitly to its type. Must be fixed once rate is 64
> +		 * bit guaranteed in clk API.
> +		 */
> +		new_opp->rate = (unsigned long)rate;
> +		goto out;
> +	}
> +
> +	ret = of_property_read_u32(np, "opp-peak-kBps", &bw);
> +	if (!ret) {
> +		new_opp->peak_bw = bw;
> +
> +		if (!of_property_read_u32(np, "opp-avg-kBps", &bw))
> +			new_opp->avg_bw = bw;

Maybe
		of_property_read_u32(np, "opp-avg-kBps", &new_opp->avg_bw);

and same for opp-peak-kbps as well.

> +	}
> +
> +out:
> +	*rate_not_available = !!ret;
> +	/*
> +	 * If ret is 0 at this point, we have already found a key. If we
> +	 * haven't found a key yet, then ret already has an error value. In
> +	 * either case, we don't need to update ret.
> +	 */
> +	of_property_read_u32(np, "opp-level", &new_opp->level);

Yes, it wasn't done earlier but we should do it now. Check level as
well and treat it as any other key.

I think add a preparatory patch first which does all the cleanup
before bandwidth thing is added.

> +
> +	return ret;
> +}
> +
>  /**
>   * _opp_add_static_v2() - Allocate static OPPs (As per 'v2' DT bindings)
>   * @opp_table:	OPP table
> @@ -558,26 +596,12 @@ static struct dev_pm_opp *_opp_add_static_v2(struct opp_table *opp_table,
>  	if (!new_opp)
>  		return ERR_PTR(-ENOMEM);
>  
> -	ret = of_property_read_u64(np, "opp-hz", &rate);
> -	if (ret < 0) {
> -		/* "opp-hz" is optional for devices like power domains. */
> -		if (!opp_table->is_genpd) {
> -			dev_err(dev, "%s: opp-hz not found\n", __func__);
> -			goto free_opp;
> -		}
> -
> -		rate_not_available = true;
> -	} else {
> -		/*
> -		 * Rate is defined as an unsigned long in clk API, and so
> -		 * casting explicitly to its type. Must be fixed once rate is 64
> -		 * bit guaranteed in clk API.
> -		 */
> -		new_opp->rate = (unsigned long)rate;
> +	ret = _read_opp_key(new_opp, np, &rate_not_available);
> +	if (ret) {
> +		dev_err(dev, "%s: opp key field not found\n", __func__);
> +		goto free_opp;
>  	}
>  
> -	of_property_read_u32(np, "opp-level", &new_opp->level);
> -
>  	/* Check if the OPP supports hardware's hierarchy of versions or not */
>  	if (!_opp_is_supported(dev, opp_table, np)) {
>  		dev_dbg(dev, "OPP not supported by hardware: %llu\n", rate);
> @@ -616,7 +640,8 @@ static struct dev_pm_opp *_opp_add_static_v2(struct opp_table *opp_table,
>  	if (of_property_read_bool(np, "opp-suspend")) {
>  		if (opp_table->suspend_opp) {
>  			/* Pick the OPP with higher rate as suspend OPP */
> -			if (new_opp->rate > opp_table->suspend_opp->rate) {
> +			if (opp_compare_key(new_opp,
> +					    opp_table->suspend_opp) > 1) {

Maybe leave this place as is as we never want to compare anything else
but rate.

>  				opp_table->suspend_opp->suspend = false;
>  				new_opp->suspend = true;
>  				opp_table->suspend_opp = new_opp;
> diff --git a/drivers/opp/opp.h b/drivers/opp/opp.h
> index 01a500e2c40a..0def3154d07b 100644
> --- a/drivers/opp/opp.h
> +++ b/drivers/opp/opp.h
> @@ -57,6 +57,8 @@ extern struct list_head opp_tables;
>   * @suspend:	true if suspend OPP
>   * @pstate: Device's power domain's performance state.
>   * @rate:	Frequency in hertz
> + * @peak_bw:	Peak bandwidth in kilobytes per second
> + * @avg_bw:	Average bandwidth in kilobytes per second
>   * @level:	Performance level
>   * @supplies:	Power supplies voltage/current values
>   * @clock_latency_ns: Latency (in nanoseconds) of switching to this OPP's
> @@ -78,6 +80,8 @@ struct dev_pm_opp {
>  	bool suspend;
>  	unsigned int pstate;
>  	unsigned long rate;
> +	unsigned int peak_bw;
> +	unsigned int avg_bw;
>  	unsigned int level;
>  
>  	struct dev_pm_opp_supply *supplies;
> @@ -213,6 +217,7 @@ struct opp_device *_add_opp_dev(const struct device *dev, struct opp_table *opp_
>  void _dev_pm_opp_find_and_remove_table(struct device *dev);
>  struct dev_pm_opp *_opp_allocate(struct opp_table *opp_table);
>  void _opp_free(struct dev_pm_opp *opp);
> +int opp_compare_key(struct dev_pm_opp *opp1, struct dev_pm_opp *opp2);

make it _opp_compare_key() instead.

>  int _opp_add(struct device *dev, struct dev_pm_opp *new_opp, struct opp_table *opp_table, bool rate_not_available);
>  int _opp_add_v1(struct opp_table *opp_table, struct device *dev, unsigned long freq, long u_volt, bool dynamic);
>  void _dev_pm_opp_cpumask_remove_table(const struct cpumask *cpumask, int last_cpu);
> -- 
> 2.24.0.393.g34dc348eaf-goog

-- 
viresh