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Subject: Re: [PATCH 02/21] tty: serial: qcom_geni_serial: Use OPP API to set
 clk/perf state
From:   Akash Asthana <akashast@codeaurora.org>
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>
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Message-ID: <575b7c8f-6b77-3da2-824e-3f128efeb466@codeaurora.org>
Date:   Fri, 10 Apr 2020 18:22:11 +0530
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Hi Rajendra,

On 4/10/2020 12:26 PM, Akash Asthana wrote:
> 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.

oops Sorry, 1st patch is intended for backward compatibility. Which I 
missed earlier.

Regards,

Akash

>
>>       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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