serial: qcom-geni: fix opp vote on shutdown

The operating-performance-point vote needs to be dropped when shutting
down the port to avoid wasting power by keeping resources like power
domains in an unnecessarily high performance state (e.g. when a UART
connected Bluetooth controller is not in use).

Fixes: a5819b548af0 ("tty: serial: qcom_geni_serial: Use OPP API to set clk/perf state")
Cc: stable@vger.kernel.org      # 5.9
Cc: Rajendra Nayak <quic_rjendra@quicinc.com>
Cc: Matthias Kaehlcke <mka@chromium.org>
Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
Acked-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Link: https://lore.kernel.org/r/20230714130214.14552-2-johan+linaro@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/serial/qcom_geni_serial.c b/drivers/tty/serial/qcom_geni_serial.c
index a1c8dcd..295dfba 100644 (file)
--- a/drivers/tty/serial/qcom_geni_serial.c
+++ b/drivers/tty/serial/qcom_geni_serial.c
@@ -125,6 +125,7 @@ struct qcom_geni_serial_port {
        dma_addr_t rx_dma_addr;
        bool setup;
        unsigned int baud;
+       unsigned long clk_rate;
        void *rx_buf;
        u32 loopback;
        bool brk;
@@ -1248,6 +1249,7 @@ static void qcom_geni_serial_set_termios(struct uart_port *uport,
                        baud * sampling_rate, clk_rate, clk_div);
 
        uport->uartclk = clk_rate;
+       port->clk_rate = 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;
@@ -1512,10 +1514,13 @@ static void qcom_geni_serial_pm(struct uart_port *uport,
 
        if (new_state == UART_PM_STATE_ON && old_state == UART_PM_STATE_OFF) {
                geni_icc_enable(&port->se);
+               if (port->clk_rate)
+                       dev_pm_opp_set_rate(uport->dev, port->clk_rate);
                geni_se_resources_on(&port->se);
        } else if (new_state == UART_PM_STATE_OFF &&
                        old_state == UART_PM_STATE_ON) {
                geni_se_resources_off(&port->se);
+               dev_pm_opp_set_rate(uport->dev, 0);
                geni_icc_disable(&port->se);
        }
 }