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

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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.

--
QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member
of Code Aurora Forum, hosted by The Linux Foundation



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