Re: [PATCH v2 01/17] tty: serial: qcom_geni_serial: Use OPP API to set clk/perf state

[Rajendra Nayak]

On 4/17/2020 11:30 PM, Matthias Kaehlcke wrote:
> Hi Rajendra,

Hey Matthias,

> On Fri, Apr 17, 2020 at 07:34:23PM +0530, Rajendra Nayak wrote:
> > geni serial needs to express a perforamnce state requirement on CX
> > powerdomain 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@xxxxxxxxxxxxxx>
> > Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> > Cc: Akash Asthana <akashast@xxxxxxxxxxxxxx>
> > Cc: linux-serial@xxxxxxxxxxxxxxx
> > ---
> >   drivers/tty/serial/qcom_geni_serial.c | 30 +++++++++++++++++++++++++-----
> >   include/linux/qcom-geni-se.h          |  2 ++
> >   2 files changed, 27 insertions(+), 5 deletions(-)
> >
> > diff --git a/drivers/tty/serial/qcom_geni_serial.c b/drivers/tty/serial/qcom_geni_serial.c
> > index 6119090..151012c 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>
> > @@ -128,6 +129,7 @@ struct qcom_geni_serial_port {
> >   	int wakeup_irq;
> >   	bool rx_tx_swap;
> >   	bool cts_rts_swap;
> > +	bool opp_table;
>
> The name of the variable suggests that it holds a OPP table, something
> like 'has_opp_table' would be clearer.

I agree with your suggestions, I will update the variable names when I respin.

> >   };
> >   
> >   static const struct uart_ops qcom_geni_console_pops;
> > @@ -961,7 +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);
> >   	ser_clk_cfg = SER_CLK_EN;
> >   	ser_clk_cfg |= clk_div << CLK_DIV_SHFT;
> >   
> > @@ -1198,8 +1200,11 @@ 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 = {
> > @@ -1318,13 +1323,20 @@ 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");
> > +	if (IS_ERR(port->se.opp))
> > +		return PTR_ERR(port->se.opp);
> > +	/* OPP table is optional */
> > +	if (!dev_pm_opp_of_add_table(&pdev->dev))
>
> Even if the OPP table is optional you probably want to fail if the error
> is anything other than -ENODEV ("'operating-points' property is not found
> or is invalid data in device node.").

sounds valid. I will fix it up and respin. Will just wait a few days to see if
I get any more reviews and feedback.

> > 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;
>
> This name suggests that the variable holds a single OPP ('struct
> dev_pm_opp'). Most other code uses the name 'opp_table', which
> also seems a good candidate here.

Agree, thanks again for taking time to review.

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