linux-kernel - Re: [PATCH] spi: fsl-dspi: Set max_speed

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Message-ID: <c865ac8ef7ab29e1529cfdde96ae4b59@agner.ch>
Date:	Tue, 22 Mar 2016 23:35:04 -0700
From:	Stefan Agner <stefan@...er.ch>
To:	Bhuvanchandra DV <bhuvanchandra.dv@...adex.com>
Cc:	broonie@...nel.org, shawnguo@...nel.org, kernel@...gutronix.de,
	haikun.wang@...escale.com, han.xu@....com,
	linux-spi@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] spi: fsl-dspi: Set max_speed_hz for master

On 2016-03-21 13:11, Bhuvanchandra DV wrote:
> Calculate and update max speed from bus clock for SoC's
> using DSPI IP.
> 
> The bus clock factor's are taken from the data sheet's
> of respective SoC's.

Plurals are without apostrophe...

I wonder if GCC optimizes this to a bit shift...

Acked-by: Stefan Agner <stefan@...er.ch>

> 
> Signed-off-by: Bhuvanchandra DV <bhuvanchandra.dv@...adex.com>
> ---
>  drivers/spi/spi-fsl-dspi.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/drivers/spi/spi-fsl-dspi.c b/drivers/spi/spi-fsl-dspi.c
> index 59a1143..8753276 100644
> --- a/drivers/spi/spi-fsl-dspi.c
> +++ b/drivers/spi/spi-fsl-dspi.c
> @@ -121,18 +121,22 @@ enum dspi_trans_mode {
>  
>  struct fsl_dspi_devtype_data {
>  	enum dspi_trans_mode trans_mode;
> +	u8 max_clock_factor;
>  };
>  
>  static const struct fsl_dspi_devtype_data vf610_data = {
>  	.trans_mode = DSPI_EOQ_MODE,
> +	.max_clock_factor = 2,
>  };
>  
>  static const struct fsl_dspi_devtype_data ls1021a_v1_data = {
>  	.trans_mode = DSPI_TCFQ_MODE,
> +	.max_clock_factor = 8,
>  };
>  
>  static const struct fsl_dspi_devtype_data ls2085a_data = {
>  	.trans_mode = DSPI_TCFQ_MODE,
> +	.max_clock_factor = 8,
>  };
>  
>  struct fsl_dspi {
> @@ -726,6 +730,9 @@ static int dspi_probe(struct platform_device *pdev)
>  	}
>  	clk_prepare_enable(dspi->clk);
>  
> +	master->max_speed_hz =
> +		clk_get_rate(dspi->clk) / dspi->devtype_data->max_clock_factor;
> +
>  	init_waitqueue_head(&dspi->waitq);
>  	platform_set_drvdata(pdev, master);