Date:   Tue, 11 Dec 2018 14:01:02 -0800
From:   Stephen Boyd <swboyd@...omium.org>
To:     Rajendra Nayak <rnayak@...eaurora.org>, andy.gross@...aro.org,
        collinsd@...eaurora.org, mka@...omium.org, robh@...nel.org,
        ulf.hansson@...aro.org, viresh.kumar@...aro.org
Cc:     devicetree@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Rajendra Nayak <rnayak@...eaurora.org>
Subject: Re: [PATCH v6 06/10] soc: qcom: rpmhpd: Add RPMh power domain driver

Quoting Rajendra Nayak (2018-12-11 01:49:34)
> The RPMh power domain driver aggregates the corner votes from various
> consumers for the ARC resources and communicates it to RPMh.
> 
> With RPMh we use 2 different numbering space for corners, one used
> by the clients to express their performance needs, and another used
> to communicate to RPMh hardware.
> 
> The clients express their performance requirements using a sparse
> numbering space which are mapped to meaningful levels like RET, SVS,
> NOMINAL, TURBO etc which then get mapped to another number space
> between 0 and 15 which is communicated to RPMh. The sparse number space,
> also referred to as vlvl is mapped to the continuous number space of 0
> to 15, also referred to as hlvl, using command DB.
> 
> Some power domain clients could request a performance state only while
> the CPU is active, while some others could request for a certain
> performance state all the time regardless of the state of the CPU.
> We handle this by internally aggregating the votes from both type of
> clients and then send the aggregated votes to RPMh.
> 
> There are also 3 different types of Votes that are comunicated to RPMh

Why capitalize vote?

> for every resource.
> 1. ACTIVE_ONLY: This specifies the requirement for the resource when the
> CPU is active
> 2. SLEEP: This specifies the requirement for the resource when the CPU
> is going to sleep
> 3. WAKE_ONLY: This specifies the requirement for the resource when the
> CPU is coming out of sleep to active state

Can you tab these in?

> 
> We add data for all power domains on sdm845 SoC as part of the patch.
> The driver can be extended to support other SoCs which support RPMh
> 
> Signed-off-by: Rajendra Nayak <rnayak@...eaurora.org>
> Reviewed-by: Ulf Hansson <ulf.hansson@...aro.org>

Just minor nitpicks ahead and a warning.

> diff --git a/drivers/soc/qcom/Makefile b/drivers/soc/qcom/Makefile
> index f1b25fdcf2ad..dd6ca92985ee 100644
> --- a/drivers/soc/qcom/Makefile
> +++ b/drivers/soc/qcom/Makefile
> @@ -22,3 +22,4 @@ obj-$(CONFIG_QCOM_APR) += apr.o
>  obj-$(CONFIG_QCOM_LLCC) += llcc-slice.o
>  obj-$(CONFIG_QCOM_SDM845_LLCC) += llcc-sdm845.o
>  obj-$(CONFIG_QCOM_RPMPD) += rpmpd.o
> +obj-$(CONFIG_QCOM_RPMHPD) += rpmhpd.o

Put this before RPMPD? At least it would be semi-sorted then.

> diff --git a/drivers/soc/qcom/rpmhpd.c b/drivers/soc/qcom/rpmhpd.c
> new file mode 100644
> index 000000000000..f993a86be48c
> --- /dev/null
> +++ b/drivers/soc/qcom/rpmhpd.c
> @@ -0,0 +1,417 @@
[..]
> +
> +static int rpmhpd_update_level_mapping(struct rpmhpd *rpmhpd)
> +{
> +       u8 buf[RPMH_ARC_MAX_LEVELS * RPMH_ARC_LEVEL_SIZE];
> +       int i, j, len, ret;
> +
> +       len = cmd_db_read_aux_data_len(rpmhpd->res_name);
> +       if (len <= 0)
> +               return len;
> +       else if (len > RPMH_ARC_MAX_LEVELS * RPMH_ARC_LEVEL_SIZE)
> +               return -EINVAL;
> +
> +       ret = cmd_db_read_aux_data(rpmhpd->res_name, buf, len);
> +       if (ret < 0)
> +               return ret;

I've changed cmd_db_read_aux_data() and that change is winding through
the arm-soc tree. This will break in the compilation phase in
linux-next.

> +
> +       rpmhpd->level_count = len / RPMH_ARC_LEVEL_SIZE;
> +
> +       for (i = 0; i < rpmhpd->level_count; i++) {
> +               rpmhpd->level[i] = 0;
> +               for (j = 0; j < RPMH_ARC_LEVEL_SIZE; j++)
> +                       rpmhpd->level[i] |=
> +                               buf[i * RPMH_ARC_LEVEL_SIZE + j] << (8 * j);
> +
> +               /*
> +                * The AUX data may be zero padded.  These 0 valued entries at
> +                * the end of the map must be ignored.
> +                */
> +               if (i > 0 && rpmhpd->level[i] == 0) {
> +                       rpmhpd->level_count = i;
> +                       break;
> +               }
> +               pr_debug("%s: ARC hlvl=%2d --> vlvl=%4u\n", rpmhpd->res_name, i,
> +                        rpmhpd->level[i]);
> +       }
> +
> +       return 0;
> +}
> +
> +static int rpmhpd_probe(struct platform_device *pdev)
> +{
> +       int i, ret;
> +       size_t num_pds;
> +       struct device *dev = &pdev->dev;
> +       struct genpd_onecell_data *data;
> +       struct rpmhpd **rpmhpds;
> +       const struct rpmhpd_desc *desc;
> +
> +       desc = of_device_get_match_data(dev);
> +       if (!desc)
> +               return -EINVAL;
> +
> +       rpmhpds = desc->rpmhpds;
> +       num_pds = desc->num_pds;
> +
> +       data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
> +       if (!data)
> +               return -ENOMEM;
> +
> +       data->domains = devm_kcalloc(dev, num_pds, sizeof(*data->domains),
> +                                    GFP_KERNEL);
> +       if (!data->domains)
> +               return -ENOMEM;
> +
> +       data->num_domains = num_pds;
> +
> +       ret = cmd_db_ready();

Does this matter? I thought we forced cmd_db_ready() in the rpmh driver
probe, and that was the parent of all rpmh devices so we should be fine
to not need to check it again here?

> +       if (ret) {
> +               if (ret != -EPROBE_DEFER)
> +                       dev_err(dev, "Command DB unavailable, ret=%d\n", ret);
> +               return ret;
> +       }
> +

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