linux-kernel - Re: [PATCH] interconnect: Add pre

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Date:   Mon, 5 Aug 2019 09:04:43 -0700
From:   Evan Green <evgreen@...omium.org>
To:     Georgi Djakov <georgi.djakov@...aro.org>
Cc:     linux-pm@...r.kernel.org, David Dai <daidavid1@...eaurora.org>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        amit.kucheria@...aro.org, Doug Anderson <dianders@...omium.org>,
        Sean Sweeney <seansw@....qualcomm.com>,
        LKML <linux-kernel@...r.kernel.org>,
        linux-arm Mailing List <linux-arm-kernel@...ts.infradead.org>,
        linux-arm-msm <linux-arm-msm@...r.kernel.org>
Subject: Re: [PATCH] interconnect: Add pre_aggregate() callback

On Mon, Aug 5, 2019 at 8:33 AM Georgi Djakov <georgi.djakov@...aro.org> wrote:
>
> Introduce an optional callback in interconnect provider drivers. It can be
> used for implementing actions, that need to be executed before the actual
> aggregation of the bandwidth requests has started.
>
> The benefit of this for now is that it will significantly simplify the code
> in provider drivers.
>
> Suggested-by: Evan Green <evgreen@...omium.org>
> Signed-off-by: Georgi Djakov <georgi.djakov@...aro.org>

Thanks Georgi, I like it! We should confirm that it actually does
allow David to remove the sum_avg_cached and max_peak_cached shadow
arrays.

> ---
>  drivers/interconnect/core.c           | 3 +++
>  include/linux/interconnect-provider.h | 3 +++
>  2 files changed, 6 insertions(+)
>
> diff --git a/drivers/interconnect/core.c b/drivers/interconnect/core.c
> index 251354bb7fdc..7b971228df38 100644
> --- a/drivers/interconnect/core.c
> +++ b/drivers/interconnect/core.c
> @@ -205,6 +205,9 @@ static int aggregate_requests(struct icc_node *node)
>         node->avg_bw = 0;
>         node->peak_bw = 0;
>
> +       if (p->pre_aggregate)
> +               p->pre_aggregate(node);
> +
>         hlist_for_each_entry(r, &node->req_list, req_node)
>                 p->aggregate(node, r->tag, r->avg_bw, r->peak_bw,
>                              &node->avg_bw, &node->peak_bw);
> diff --git a/include/linux/interconnect-provider.h b/include/linux/interconnect-provider.h
> index 4ee19fd41568..fd42bd19302d 100644
> --- a/include/linux/interconnect-provider.h
> +++ b/include/linux/interconnect-provider.h
> @@ -36,6 +36,8 @@ struct icc_node *of_icc_xlate_onecell(struct of_phandle_args *spec,
>   * @nodes: internal list of the interconnect provider nodes
>   * @set: pointer to device specific set operation function
>   * @aggregate: pointer to device specific aggregate operation function
> + * @pre_aggregate: pointer to device specific function that is called
> + *                before the aggregation begins (optional)
>   * @xlate: provider-specific callback for mapping nodes from phandle arguments
>   * @dev: the device this interconnect provider belongs to
>   * @users: count of active users
> @@ -47,6 +49,7 @@ struct icc_provider {
>         int (*set)(struct icc_node *src, struct icc_node *dst);
>         int (*aggregate)(struct icc_node *node, u32 tag, u32 avg_bw,
>                          u32 peak_bw, u32 *agg_avg, u32 *agg_peak);
> +       int (*pre_aggregate)(struct icc_node *node);
>         struct icc_node* (*xlate)(struct of_phandle_args *spec, void *data);
>         struct device           *dev;
>         int                     users;