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Subject: Re: [PATCH 02/21] tty: serial: qcom_geni_serial: Use OPP API to set
 clk/perf state
To:     Rajendra Nayak <rnayak@codeaurora.org>, viresh.kumar@linaro.org,
        sboyd@kernel.org, bjorn.andersson@linaro.org, agross@kernel.org
Cc:     linux-arm-msm@vger.kernel.org, devicetree@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org
References: <1586353607-32222-1-git-send-email-rnayak@codeaurora.org>
 <1586353607-32222-3-git-send-email-rnayak@codeaurora.org>
From:   Akash Asthana <akashast@codeaurora.org>
Message-ID: <5eb6c05e-893a-ef8a-c53e-a775b2f837d1@codeaurora.org>
Date:   Fri, 10 Apr 2020 12:26:18 +0530
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Hi Rajendra,

On 4/8/2020 7:16 PM, Rajendra Nayak wrote:
> geni serial needs to express a perforamnce state requirement on CX
*performance
> depending on the frequency of the clock rates. Use OPP table from
> DT to register with OPP framework and use dev_pm_opp_set_rate() to
> set the clk/perf state.
>
> Signed-off-by: Rajendra Nayak <rnayak@codeaurora.org>
> Cc: Akash Asthana <akashast@codeaurora.org>
> Cc: linux-serial@vger.kernel.org
> ---
>   drivers/tty/serial/qcom_geni_serial.c | 20 +++++++++++++++-----
>   include/linux/qcom-geni-se.h          |  2 ++
>   2 files changed, 17 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/tty/serial/qcom_geni_serial.c b/drivers/tty/serial/qcom_geni_serial.c
> index 6119090..754eaf6 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>
> @@ -961,7 +962,7 @@ 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);

Is this change not intended for backward compatibility? If I don't pick 
DT change for Geni drivers,  dev_pm_opp_set_rate is failing and causing 
functionality issues.

>   	ser_clk_cfg = SER_CLK_EN;
>   	ser_clk_cfg |= clk_div << CLK_DIV_SHFT;
>   
> @@ -1198,8 +1199,10 @@ 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) {
> +		dev_pm_opp_set_rate(uport->dev, 0);
>   		geni_se_resources_off(&port->se);
> +	}
>   }
>   
>   static const struct uart_ops qcom_geni_console_pops = {
> @@ -1318,13 +1321,16 @@ 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 = dev_pm_opp_set_clkname(&pdev->dev, "se");
> +	dev_pm_opp_of_add_table(&pdev->dev);
> +
>   	uport->private_data = drv;
>   	platform_set_drvdata(pdev, port);
>   	port->handle_rx = console ? handle_rx_console : handle_rx_uart;
>   
>   	ret = uart_add_one_port(drv, uport);
>   	if (ret)
> -		return ret;
> +		goto err;
>   
>   	irq_set_status_flags(uport->irq, IRQ_NOAUTOEN);
>   	ret = devm_request_irq(uport->dev, uport->irq, qcom_geni_serial_isr,
> @@ -1332,7 +1338,7 @@ static int qcom_geni_serial_probe(struct platform_device *pdev)
>   	if (ret) {
>   		dev_err(uport->dev, "Failed to get IRQ ret %d\n", ret);
>   		uart_remove_one_port(drv, uport);
> -		return ret;
> +		goto err;
>   	}
>   
>   	/*
> @@ -1349,11 +1355,14 @@ static int qcom_geni_serial_probe(struct platform_device *pdev)
>   		if (ret) {
>   			device_init_wakeup(&pdev->dev, false);
>   			uart_remove_one_port(drv, uport);
> -			return ret;
> +			goto err;
>   		}
>   	}
>   
>   	return 0;
> +err:
> +	dev_pm_opp_of_remove_table(&pdev->dev);
do we need to call "dev_pm_opp_put_clkname" here and in remove to 
release clk resource grabbed by

dev_pm_opp_set_clkname(&pdev->dev, "se");?

Regards,
Akash

> +	return ret;
>   }
>   
>   static int qcom_geni_serial_remove(struct platform_device *pdev)
> @@ -1361,6 +1370,7 @@ static int qcom_geni_serial_remove(struct platform_device *pdev)
>   	struct qcom_geni_serial_port *port = platform_get_drvdata(pdev);
>   	struct uart_driver *drv = port->uport.private_data;
>   
> +	dev_pm_opp_of_remove_table(&pdev->dev);
>   	dev_pm_clear_wake_irq(&pdev->dev);
>   	device_init_wakeup(&pdev->dev, false);
>   	uart_remove_one_port(drv, &port->uport);
> diff --git a/include/linux/qcom-geni-se.h b/include/linux/qcom-geni-se.h
> index dd46494..737e713 100644
> --- a/include/linux/qcom-geni-se.h
> +++ b/include/linux/qcom-geni-se.h
> @@ -24,6 +24,7 @@ enum geni_se_protocol_type {
>   
>   struct geni_wrapper;
>   struct clk;
> +struct opp_table;
>   
>   /**
>    * struct geni_se - GENI Serial Engine
> @@ -39,6 +40,7 @@ struct geni_se {
>   	struct device *dev;
>   	struct geni_wrapper *wrapper;
>   	struct clk *clk;
> +	struct opp_table *opp;
>   	unsigned int num_clk_levels;
>   	unsigned long *clk_perf_tbl;
>   };

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