linux-kernel - Re: [RESEND PATCH 2/2] soc: qcom: rpmhpd: Make power

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Message-ID: <45bfb6ae-d131-10d7-1924-48c98a957667@linaro.org>
Date:   Thu, 12 Aug 2021 16:21:07 +0300
From:   Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To:     Bjorn Andersson <bjorn.andersson@...aro.org>,
        Andy Gross <agross@...nel.org>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        Stephen Boyd <swboyd@...omium.org>,
        Rajendra Nayak <rnayak@...eaurora.org>
Cc:     linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [RESEND PATCH 2/2] soc: qcom: rpmhpd: Make power_on actually
 enable the domain

On 03/07/2021 05:54, Bjorn Andersson wrote:
> The general expectation is that powering on a power-domain should make
> the power domain deliver some power, and if a specific performace state
> is needed further requests has to be made.
> 
> But in contrast with other power-domain implementations (e.g. rpmpd) the
> RPMh does not have an interface to enable the power, so the driver has
> to vote for a particular corner (performance level) in rpmh_power_on().
> 
> But the corner is never initialized, so a typical request to simply
> enable the power domain would not actually turn on the hardware. Further
> more, when no more clients vote for a performance state (i.e. the
> aggregated vote is 0) the power domain would be turn off.
> 
> Fix both of these issues by always voting for a corner with non-zero
> value, when the power domain is enabled.
> 
> The tracking of the lowest non-zero corner is performed to handle the
> corner case if there's ever a domain with a non-zero lowest corner, in
> which case both rpmh_power_on() and rpmh_rpmhpd_set_performance_state()
> would be allowed to use this lowest corner.
> 
> Fixes: 279b7e8a62cc ("soc: qcom: rpmhpd: Add RPMh power domain driver")
> Signed-off-by: Bjorn Andersson <bjorn.andersson@...aro.org>
> ---
> 
> Resending because the hunk in rpmhpd_update_level_mapping() was left in the
> index.

So, colleagues, what is the fate of this patch? Is it going to be 
applied? Or we agree that current approach (power_on + 
set_performance_state) is the expected behaviour? My patches on gdsc 
rework depend on this patch, but I can rework in them in favour of 
required-opp approach.

> 
>   drivers/soc/qcom/rpmhpd.c | 18 ++++++++++++++----
>   1 file changed, 14 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/soc/qcom/rpmhpd.c b/drivers/soc/qcom/rpmhpd.c
> index fa209b479ab3..76ea6b053ef0 100644
> --- a/drivers/soc/qcom/rpmhpd.c
> +++ b/drivers/soc/qcom/rpmhpd.c
> @@ -30,6 +30,7 @@
>    * @active_only:	True if it represents an Active only peer
>    * @corner:		current corner
>    * @active_corner:	current active corner
> + * @enable_corner:	lowest non-zero corner
>    * @level:		An array of level (vlvl) to corner (hlvl) mappings
>    *			derived from cmd-db
>    * @level_count:	Number of levels supported by the power domain. max
> @@ -47,6 +48,7 @@ struct rpmhpd {
>   	const bool	active_only;
>   	unsigned int	corner;
>   	unsigned int	active_corner;
> +	unsigned int	enable_corner;
>   	u32		level[RPMH_ARC_MAX_LEVELS];
>   	size_t		level_count;
>   	bool		enabled;
> @@ -385,13 +387,13 @@ static int rpmhpd_aggregate_corner(struct rpmhpd *pd, unsigned int corner)
>   static int rpmhpd_power_on(struct generic_pm_domain *domain)
>   {
>   	struct rpmhpd *pd = domain_to_rpmhpd(domain);
> -	int ret = 0;
> +	unsigned int corner;
> +	int ret;
>   
>   	mutex_lock(&rpmhpd_lock);
>   
> -	if (pd->corner)
> -		ret = rpmhpd_aggregate_corner(pd, pd->corner);
> -
> +	corner = max(pd->corner, pd->enable_corner);
> +	ret = rpmhpd_aggregate_corner(pd, corner);
>   	if (!ret)
>   		pd->enabled = true;
>   
> @@ -436,6 +438,10 @@ static int rpmhpd_set_performance_state(struct generic_pm_domain *domain,
>   		i--;
>   
>   	if (pd->enabled) {
> +		/* Ensure that the domain isn't turn off */
> +		if (i < pd->enable_corner)
> +			i = pd->enable_corner;
> +
>   		ret = rpmhpd_aggregate_corner(pd, i);
>   		if (ret)
>   			goto out;
> @@ -472,6 +478,10 @@ static int rpmhpd_update_level_mapping(struct rpmhpd *rpmhpd)
>   	for (i = 0; i < rpmhpd->level_count; i++) {
>   		rpmhpd->level[i] = buf[i];
>   
> +		/* Remember the first non-zero corner */
> +		if (!rpmhpd->enable_corner)
> +			rpmhpd->enable_corner = i;
> +
>   		/*
>   		 * The AUX data may be zero padded.  These 0 valued entries at
>   		 * the end of the map must be ignored.
> 


-- 
With best wishes
Dmitry