Re: [PATCH 02/21] tty: serial: qcom_geni_serial: Use OPP API to set clk/perf state

Matthias Kaehlcke
2020-04-09T17:45:16Z

Hi Rajendra,

On Wed, Apr 08, 2020 at 07:16:28PM +0530, Rajendra Nayak wrote:
> geni serial needs to express a perforamnce state requirement on CX
> 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);
> 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_set_clkname() can fail for multiple reasons, it seems an error
check would be warranted.

Is it actually necessary to save the OPP table in 'struct geni_se'? Both
the serial and the SPI driver save the table, but don't use it later (nor
does the SE driver).