[U-Boot] [PATCH] mxc_spi: Round up clock divider

[Stefano Babic]

On 10/08/2012 20:51, Benoît Thébaudeau wrote:
> Since the input frequency of the API is a maximum that should not be exceeded in
> order for the devices to operate properly, the SPI clock divider should be
> rounded up, not truncated.
> 

Hi Benoît,

> Signed-off-by: Benoît Thébaudeau <benoit.thebaudeau at advansee.com>
> Cc: Wolfgang Denk <wd at denx.de>
> Cc: Stefano Babic <sbabic at denx.de>
> ---
>  .../drivers/spi/mxc_spi.c                          |    4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git u-boot-4d3c95f.orig/drivers/spi/mxc_spi.c u-boot-4d3c95f/drivers/spi/mxc_spi.c
> index 2e15318..cf1462f 100644
> --- u-boot-4d3c95f.orig/drivers/spi/mxc_spi.c
> +++ u-boot-4d3c95f/drivers/spi/mxc_spi.c
> @@ -96,7 +96,7 @@ static s32 spi_cfg_mxc(struct mxc_spi_slave *mxcs, unsigned int cs,
>  
>  	clk_src = mxc_get_clock(MXC_CSPI_CLK);
>  
> -	div = clk_src / max_hz;
> +	div = DIV_ROUND_UP(clk_src, max_hz);
>  	div = get_cspi_div(div);
>  
>  	debug("clk %d Hz, div %d, real clk %d Hz\n",
> @@ -147,7 +147,7 @@ static s32 spi_cfg_mxc(struct mxc_spi_slave *mxcs, unsigned int cs,
>  	 * The following computation is taken directly from Freescale's code.
>  	 */
>  	if (clk_src > max_hz) {
> -		pre_div = clk_src / max_hz;
> +		pre_div = DIV_ROUND_UP(clk_src, max_hz);
>  		if (pre_div > 16) {
>  			post_div = pre_div / 16;
>  			pre_div = 15;
> 

Agree - do you also get a case where the divider was too low and the SPI
does not work or it was only examining the code ?

Acked-by: Stefano Babic <sbabic at denx.de>

Best regards,
Stefano Babic

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