linux-kernel - Re: [PATCH v6 6/8] serial: qcom-geni: move clock-rate logic to separate function

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Message-ID: <509c94bb-cf31-43bb-a92d-db006efd43aa@quicinc.com>
Date: Mon, 16 Jun 2025 21:34:27 +0530
From: Praveen Talari <quic_ptalari@...cinc.com>
To: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby
	<jirislaby@...nel.org>, Rob Herring <robh@...nel.org>,
        Krzysztof Kozlowski
	<krzk+dt@...nel.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Bjorn Andersson
	<andersson@...nel.org>,
        Konrad Dybcio <konradybcio@...nel.org>,
        <linux-arm-msm@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linux-serial@...r.kernel.org>, <devicetree@...r.kernel.org>,
        "Bryan
 O'Donoghue" <bryan.odonoghue@...aro.org>
CC: <psodagud@...cinc.com>, <djaggi@...cinc.com>, <quic_msavaliy@...cinc.com>,
        <quic_vtanuku@...cinc.com>, <quic_arandive@...cinc.com>,
        <quic_mnaresh@...cinc.com>, <quic_shazhuss@...cinc.com>
Subject: Re: [PATCH v6 6/8] serial: qcom-geni: move clock-rate logic to
 separate function

Hi Bryan,

Gentle reminder!!

Thanks,
Praveen Talari

On 6/6/2025 10:51 PM, Praveen Talari wrote:
> Facilitates future modifications within the new function,
> leading to better readability and maintainability of the code.
> 
> Move the code that handles the actual logic of clock-rate
> calculations to a separate function geni_serial_set_rate()
> which enhances code readability.
> 
> Signed-off-by: Praveen Talari <quic_ptalari@...cinc.com>
> ---
> v5 -> v6
> - used "unsigned int" instead of "unsigned long" in newly
>    added API function params to avoid the format specifier
>    warnings.
> 
> v3 -> v4
> - added version log after ---
> 
> v1 -> v2
> - resolved build warnings for datatype format specifiers
> - removed double spaces in log
> ---
>   drivers/tty/serial/qcom_geni_serial.c | 56 +++++++++++++++++----------
>   1 file changed, 36 insertions(+), 20 deletions(-)
> 
> diff --git a/drivers/tty/serial/qcom_geni_serial.c b/drivers/tty/serial/qcom_geni_serial.c
> index 715db35bab2f..b6fa7dc9b1fb 100644
> --- a/drivers/tty/serial/qcom_geni_serial.c
> +++ b/drivers/tty/serial/qcom_geni_serial.c
> @@ -1283,27 +1283,14 @@ static unsigned long get_clk_div_rate(struct clk *clk, unsigned int baud,
>   	return ser_clk;
>   }
>   
> -static void qcom_geni_serial_set_termios(struct uart_port *uport,
> -					 struct ktermios *termios,
> -					 const struct ktermios *old)
> +static int geni_serial_set_rate(struct uart_port *uport, unsigned int baud)
>   {
> -	unsigned int baud;
> -	u32 bits_per_char;
> -	u32 tx_trans_cfg;
> -	u32 tx_parity_cfg;
> -	u32 rx_trans_cfg;
> -	u32 rx_parity_cfg;
> -	u32 stop_bit_len;
> -	unsigned int clk_div;
> -	u32 ser_clk_cfg;
>   	struct qcom_geni_serial_port *port = to_dev_port(uport);
>   	unsigned long clk_rate;
> -	u32 ver, sampling_rate;
>   	unsigned int avg_bw_core;
> -	unsigned long timeout;
> -
> -	/* baud rate */
> -	baud = uart_get_baud_rate(uport, termios, old, 300, 4000000);
> +	unsigned int clk_div;
> +	u32 ver, sampling_rate;
> +	u32 ser_clk_cfg;
>   
>   	sampling_rate = UART_OVERSAMPLING;
>   	/* Sampling rate is halved for IP versions >= 2.5 */
> @@ -1317,7 +1304,7 @@ static void qcom_geni_serial_set_termios(struct uart_port *uport,
>   		dev_err(port->se.dev,
>   			"Couldn't find suitable clock rate for %u\n",
>   			baud * sampling_rate);
> -		return;
> +		return -EINVAL;
>   	}
>   
>   	dev_dbg(port->se.dev, "desired_rate = %u, clk_rate = %lu, clk_div = %u\n",
> @@ -1339,6 +1326,37 @@ static void qcom_geni_serial_set_termios(struct uart_port *uport,
>   	port->se.icc_paths[CPU_TO_GENI].avg_bw = Bps_to_icc(baud);
>   	geni_icc_set_bw(&port->se);
>   
> +	writel(ser_clk_cfg, uport->membase + GENI_SER_M_CLK_CFG);
> +	writel(ser_clk_cfg, uport->membase + GENI_SER_S_CLK_CFG);
> +	return 0;
> +}
> +
> +static void qcom_geni_serial_set_termios(struct uart_port *uport,
> +					 struct ktermios *termios,
> +					 const struct ktermios *old)
> +{
> +	struct qcom_geni_serial_port *port = to_dev_port(uport);
> +	unsigned int baud;
> +	unsigned long timeout;
> +	u32 bits_per_char;
> +	u32 tx_trans_cfg;
> +	u32 tx_parity_cfg;
> +	u32 rx_trans_cfg;
> +	u32 rx_parity_cfg;
> +	u32 stop_bit_len;
> +	int ret = 0;
> +
> +	/* baud rate */
> +	baud = uart_get_baud_rate(uport, termios, old, 300, 4000000);
> +
> +	ret = geni_serial_set_rate(uport, baud);
> +	if (ret) {
> +		dev_err(port->se.dev,
> +			"%s: Failed to set baud:%u ret:%d\n",
> +			__func__, baud, ret);
> +		return;
> +	}
> +
>   	/* parity */
>   	tx_trans_cfg = readl(uport->membase + SE_UART_TX_TRANS_CFG);
>   	tx_parity_cfg = readl(uport->membase + SE_UART_TX_PARITY_CFG);
> @@ -1406,8 +1424,6 @@ static void qcom_geni_serial_set_termios(struct uart_port *uport,
>   	writel(bits_per_char, uport->membase + SE_UART_TX_WORD_LEN);
>   	writel(bits_per_char, uport->membase + SE_UART_RX_WORD_LEN);
>   	writel(stop_bit_len, uport->membase + SE_UART_TX_STOP_BIT_LEN);
> -	writel(ser_clk_cfg, uport->membase + GENI_SER_M_CLK_CFG);
> -	writel(ser_clk_cfg, uport->membase + GENI_SER_S_CLK_CFG);
>   }
>   
>   #ifdef CONFIG_SERIAL_QCOM_GENI_CONSOLE