linux-kernel - Re: [PATCH v6 1/6] tty: serial: qcom_geni_serial: Use OPP API to set clk/perf state

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Message-ID: <159347264530.1987609.11350620235820019545@swboyd.mtv.corp.google.com>
Date:   Mon, 29 Jun 2020 16:17:25 -0700
From:   Stephen Boyd <swboyd@...omium.org>
To:     Rajendra Nayak <rnayak@...eaurora.org>, agross@...nel.org,
        bjorn.andersson@...aro.org, robdclark@...omium.org,
        robdclark@...il.com, stanimir.varbanov@...aro.org
Cc:     viresh.kumar@...aro.org, mka@...omium.org,
        linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
        Rajendra Nayak <rnayak@...eaurora.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Akash Asthana <akashast@...eaurora.org>,
        linux-serial@...r.kernel.org
Subject: Re: [PATCH v6 1/6] tty: serial: qcom_geni_serial: Use OPP API to set clk/perf state

Quoting Rajendra Nayak (2020-06-15 05:02:39)
> diff --git a/drivers/tty/serial/qcom_geni_serial.c b/drivers/tty/serial/qcom_geni_serial.c
> index 457c0bf..a90f8ec 100644
> --- a/drivers/tty/serial/qcom_geni_serial.c
> +++ b/drivers/tty/serial/qcom_geni_serial.c
> @@ -9,6 +9,7 @@
>  #include <linux/module.h>
>  #include <linux/of.h>
>  #include <linux/of_device.h>
> +#include <linux/pm_opp.h>
>  #include <linux/platform_device.h>
>  #include <linux/pm_runtime.h>
>  #include <linux/pm_wakeirq.h>
> @@ -962,7 +963,7 @@ static void qcom_geni_serial_set_termios(struct uart_port *uport,
>                 goto out_restart_rx;
>  
>         uport->uartclk = clk_rate;
> -       clk_set_rate(port->se.clk, clk_rate);
> +       dev_pm_opp_set_rate(uport->dev, clk_rate);

If there isn't an OPP table for the device because it is optional then
how can we unconditionally call dev_pm_opp_set_rate()?

>         ser_clk_cfg = SER_CLK_EN;
>         ser_clk_cfg |= clk_div << CLK_DIV_SHFT;
>  
> @@ -1231,8 +1232,11 @@ static void qcom_geni_serial_pm(struct uart_port *uport,
>         if (new_state == UART_PM_STATE_ON && old_state == UART_PM_STATE_OFF)
>                 geni_se_resources_on(&port->se);
>         else if (new_state == UART_PM_STATE_OFF &&
> -                       old_state == UART_PM_STATE_ON)
> +                       old_state == UART_PM_STATE_ON) {
> +               /* Drop the performance state vote */
> +               dev_pm_opp_set_rate(uport->dev, 0);
>                 geni_se_resources_off(&port->se);
> +       }
>  }
>  
>  static const struct uart_ops qcom_geni_console_pops = {
> @@ -1351,13 +1355,25 @@ static int qcom_geni_serial_probe(struct platform_device *pdev)
>         if (of_property_read_bool(pdev->dev.of_node, "cts-rts-swap"))
>                 port->cts_rts_swap = true;
>  
> +       port->se.opp_table = dev_pm_opp_set_clkname(&pdev->dev, "se");
> +       if (IS_ERR(port->se.opp_table))
> +               return PTR_ERR(port->se.opp_table);
> +       /* OPP table is optional */
> +       ret = dev_pm_opp_of_add_table(&pdev->dev);
> +       if (!ret) {
> +               port->se.has_opp_table = true;
> +       } else if (ret != -ENODEV) {
> +               dev_err(&pdev->dev, "invalid OPP table in device tree\n");
> +               return ret;
> +       }

At least it looks optional here.