Re: [PATCH 2/6] tty: serial: qcom_geni_serial: Add interconnect support

[Bjorn Andersson <bjorn.andersson-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>]

On Mon 17 Feb 05:30 PST 2020, Akash Asthana wrote:

> Get the interconnect paths for Uart based Serial Engine device
> and vote according to the baud rate requirement of the driver.
> 
> Signed-off-by: Akash Asthana <akashast-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org>
> ---
>  drivers/tty/serial/qcom_geni_serial.c | 84 ++++++++++++++++++++++++++++++-----
>  1 file changed, 74 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/tty/serial/qcom_geni_serial.c b/drivers/tty/serial/qcom_geni_serial.c
> index 191abb1..a8fb2b7 100644
> --- a/drivers/tty/serial/qcom_geni_serial.c
> +++ b/drivers/tty/serial/qcom_geni_serial.c
> @@ -174,6 +174,35 @@ static struct qcom_geni_serial_port qcom_geni_console_port = {
>  	},
>  };
>  
> +static int geni_serial_icc_get(struct geni_se *se)
> +{
> +	if (!se)

If se == NULL the kernel has already oopsed as it dereferenced port->se
a few lines before calling this function.

> +		return -EINVAL;
> +
> +	se->icc_path[GENI_TO_CORE] = of_icc_get(se->dev, "qup-core");
> +	if (IS_ERR(se->icc_path[GENI_TO_CORE]))
> +		return PTR_ERR(se->icc_path[GENI_TO_CORE]);
> +
> +	se->icc_path[CPU_TO_GENI] = of_icc_get(se->dev, "qup-config");
> +	if (IS_ERR(se->icc_path[CPU_TO_GENI])) {
> +		icc_put(se->icc_path[GENI_TO_CORE]);
> +		se->icc_path[GENI_TO_CORE] = NULL;

You're going to fail probe when this happens, so why the need to reset
this path?

> +		return PTR_ERR(se->icc_path[CPU_TO_GENI]);
> +	}
> +
> +	return 0;
> +}
> +
> +void geni_serial_icc_put(struct geni_se *se)
> +{
> +	int i;
> +
> +	for (i = 0; i < ARRAY_SIZE(se->icc_path); i++) {
> +		icc_put(se->icc_path[i]);

In geni_serial_icc_get() you hard open code this loop, so why not do the
same here, to maintain some symmetry.

> +		se->icc_path[i] = NULL;

Again, what's the purpose of this clear?

> +	}
> +}
> +
>  static int qcom_geni_serial_request_port(struct uart_port *uport)
>  {
>  	struct platform_device *pdev = to_platform_device(uport->dev);
> @@ -949,6 +978,12 @@ static void qcom_geni_serial_set_termios(struct uart_port *uport,
>  	ser_clk_cfg = SER_CLK_EN;
>  	ser_clk_cfg |= clk_div << CLK_DIV_SHFT;
>  
> +	/* Put BW vote only on CPU path as driver supports FIFO mode only */
> +	port->se.avg_bw_cpu = Bps_to_icc(baud);
> +	port->se.peak_bw_cpu = Bps_to_icc(2 * baud);
> +	icc_set_bw(port->se.icc_path[CPU_TO_GENI], port->se.avg_bw_cpu,
> +			port->se.peak_bw_cpu);
> +
>  	/* parity */
>  	tx_trans_cfg = readl(uport->membase + SE_UART_TX_TRANS_CFG);
>  	tx_parity_cfg = readl(uport->membase + SE_UART_TX_PARITY_CFG);
> @@ -1179,11 +1214,20 @@ static void qcom_geni_serial_pm(struct uart_port *uport,
>  	if (old_state == UART_PM_STATE_UNDEFINED)
>  		old_state = UART_PM_STATE_OFF;
>  
> -	if (new_state == UART_PM_STATE_ON && old_state == UART_PM_STATE_OFF)
> +	if (new_state == UART_PM_STATE_ON && old_state == UART_PM_STATE_OFF) {
> +		/* Put BW vote for core clocks and CPU */
> +		icc_set_bw(port->se.icc_path[GENI_TO_CORE],
> +			port->se.avg_bw_core, port->se.peak_bw_core);
> +		icc_set_bw(port->se.icc_path[CPU_TO_GENI], port->se.avg_bw_cpu,
> +			port->se.peak_bw_cpu);
>  		geni_se_resources_on(&port->se);
> -	else if (new_state == UART_PM_STATE_OFF &&
> -			old_state == UART_PM_STATE_ON)
> +	} else if (new_state == UART_PM_STATE_OFF &&
> +			old_state == UART_PM_STATE_ON) {
>  		geni_se_resources_off(&port->se);
> +		/* Remove BW vote from core clocks and CPU */
> +		icc_set_bw(port->se.icc_path[GENI_TO_CORE], 0, 0);
> +		icc_set_bw(port->se.icc_path[CPU_TO_GENI], 0, 0);
> +	}
>  }
>  
>  static const struct uart_ops qcom_geni_console_pops = {
> @@ -1274,15 +1318,30 @@ static int qcom_geni_serial_probe(struct platform_device *pdev)
>  	port->rx_fifo_depth = DEF_FIFO_DEPTH_WORDS;
>  	port->tx_fifo_width = DEF_FIFO_WIDTH_BITS;
>  
> +	ret = geni_serial_icc_get(&port->se);
> +	if (ret)
> +		return ret;
> +	/* Set the bus quota to a reasonable value */
> +	port->se.avg_bw_core = console ? Bps_to_icc(1000) :
> +		Bps_to_icc(CORE_2X_50_MHZ);
> +	port->se.peak_bw_core = console ? Bps_to_icc(1000) :
> +		Bps_to_icc(CORE_2X_100_MHZ);
> +	port->se.avg_bw_cpu = Bps_to_icc(1000);
> +	port->se.avg_bw_cpu = Bps_to_icc(1000);
> +
>  	port->name = devm_kasprintf(uport->dev, GFP_KERNEL,
>  			"qcom_geni_serial_%s%d",
>  			uart_console(uport) ? "console" : "uart", uport->line);
> -	if (!port->name)
> -		return -ENOMEM;
> +	if (!port->name) {
> +		ret = -ENOMEM;
> +		goto geni_serial_put_icc;

Rather than reworking the error handling like this, please introduce a
devm_icc_get() function in the interconnect API.

Regards,
Bjorn

> +	}
>  
>  	irq = platform_get_irq(pdev, 0);
> -	if (irq < 0)
> -		return irq;
> +	if (irq < 0) {
> +		ret = irq;
> +		goto geni_serial_put_icc;
> +	}
>  	uport->irq = irq;
>  	uport->has_sysrq = IS_ENABLED(CONFIG_SERIAL_QCOM_GENI_CONSOLE);
>  
> @@ -1295,7 +1354,7 @@ static int qcom_geni_serial_probe(struct platform_device *pdev)
>  
>  	ret = uart_add_one_port(drv, uport);
>  	if (ret)
> -		return ret;
> +		goto geni_serial_put_icc;
>  
>  	irq_set_status_flags(uport->irq, IRQ_NOAUTOEN);
>  	ret = devm_request_irq(uport->dev, uport->irq, qcom_geni_serial_isr,
> @@ -1303,7 +1362,7 @@ 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 geni_serial_put_icc;
>  	}
>  
>  	/*
> @@ -1320,11 +1379,15 @@ 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 geni_serial_put_icc;
>  		}
>  	}
>  
>  	return 0;
> +
> +geni_serial_put_icc:
> +	geni_serial_icc_put(&port->se);
> +	return ret;
>  }
>  
>  static int qcom_geni_serial_remove(struct platform_device *pdev)
> @@ -1335,6 +1398,7 @@ static int qcom_geni_serial_remove(struct platform_device *pdev)
>  	dev_pm_clear_wake_irq(&pdev->dev);
>  	device_init_wakeup(&pdev->dev, false);
>  	uart_remove_one_port(drv, &port->uport);
> +	geni_serial_icc_put(&port->se);
>  
>  	return 0;
>  }
> -- 
> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,\na Linux Foundation Collaborative Project