linux-kernel - Re: [PATCH] spi: imx: remove CLK calculation and check for target mode

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Message-ID: <aPucJCNbyptl2kX+@lizhi-Precision-Tower-5810>
Date: Fri, 24 Oct 2025 11:32:52 -0400
From: Frank Li <Frank.li@....com>
To: carlos.song@....com
Cc: broonie@...nel.org, shawnguo@...nel.org, s.hauer@...gutronix.de,
	kernel@...gutronix.de, festevam@...il.com,
	linux-spi@...r.kernel.org, imx@...ts.linux.dev,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] spi: imx: remove CLK calculation and check for target
 mode

On Fri, Oct 24, 2025 at 01:52:11PM +0800, carlos.song@....com wrote:
> From: Clark Wang <xiaoning.wang@....com>
>
> In target mode, the clock signal is controlled by the master. Target does
> not need to check, calculate and configure the clock frequency division.
> The target can directly use the root clock to sample the SCL signal.
>
> Therefore, remove check, calculation and frequency division function of
> the clock for target mode.
>
> Signed-off-by: Carlos Song <carlos.song@....com>
> Signed-off-by: Clark Wang <xiaoning.wang@....com>
> ---

Reviewed-by: Frank Li <Frank.Li@....com>

>  drivers/spi/spi-imx.c | 28 ++++++++++++++++++----------
>  1 file changed, 18 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/spi/spi-imx.c b/drivers/spi/spi-imx.c
> index 4ffee6c5d5c4..6eb4bfb7be4a 100644
> --- a/drivers/spi/spi-imx.c
> +++ b/drivers/spi/spi-imx.c
> @@ -42,6 +42,7 @@ MODULE_PARM_DESC(polling_limit_us,
>  		 "time in us to run a transfer in polling mode\n");
>
>  #define MXC_RPM_TIMEOUT		2000 /* 2000ms */
> +#define MXC_SPI_DEFAULT_SPEED	500000 /* 500KHz */
>
>  #define MXC_CSPIRXDATA		0x00
>  #define MXC_CSPITXDATA		0x04
> @@ -692,8 +693,11 @@ static int mx51_ecspi_prepare_transfer(struct spi_imx_data *spi_imx,
>  	/* set clock speed */
>  	ctrl &= ~(0xf << MX51_ECSPI_CTRL_POSTDIV_OFFSET |
>  		  0xf << MX51_ECSPI_CTRL_PREDIV_OFFSET);
> -	ctrl |= mx51_ecspi_clkdiv(spi_imx, spi_imx->spi_bus_clk, &clk);
> -	spi_imx->spi_bus_clk = clk;
> +
> +	if (!spi_imx->target_mode) {
> +		ctrl |= mx51_ecspi_clkdiv(spi_imx, spi_imx->spi_bus_clk, &clk);
> +		spi_imx->spi_bus_clk = clk;
> +	}
>
>  	mx51_configure_cpha(spi_imx, spi);
>
> @@ -1316,15 +1320,18 @@ static int spi_imx_setupxfer(struct spi_device *spi,
>  	if (!t)
>  		return 0;
>
> -	if (!t->speed_hz) {
> -		if (!spi->max_speed_hz) {
> -			dev_err(&spi->dev, "no speed_hz provided!\n");
> -			return -EINVAL;
> +	if (!spi_imx->target_mode) {
> +		if (!t->speed_hz) {
> +			if (!spi->max_speed_hz) {
> +				dev_err(&spi->dev, "no speed_hz provided!\n");
> +				return -EINVAL;
> +			}
> +			dev_dbg(&spi->dev, "using spi->max_speed_hz!\n");
> +			spi_imx->spi_bus_clk = spi->max_speed_hz;
> +		} else {
> +			spi_imx->spi_bus_clk = t->speed_hz;
>  		}
> -		dev_dbg(&spi->dev, "using spi->max_speed_hz!\n");
> -		spi_imx->spi_bus_clk = spi->max_speed_hz;
> -	} else
> -		spi_imx->spi_bus_clk = t->speed_hz;
> +	}
>
>  	spi_imx->bits_per_word = t->bits_per_word;
>  	spi_imx->count = t->len;
> @@ -1839,6 +1846,7 @@ static int spi_imx_probe(struct platform_device *pdev)
>  	controller->prepare_message = spi_imx_prepare_message;
>  	controller->unprepare_message = spi_imx_unprepare_message;
>  	controller->target_abort = spi_imx_target_abort;
> +	spi_imx->spi_bus_clk = MXC_SPI_DEFAULT_SPEED;
>  	controller->mode_bits = SPI_CPOL | SPI_CPHA | SPI_CS_HIGH | SPI_NO_CS |
>  				SPI_MOSI_IDLE_LOW;
>
> --
> 2.34.1
>