Re: [PATCH] spi: davinci: Support DMA transfers larger than 65535 words

[Sergei Shtylyov <sshtylyov-Igf4POYTYCDQT0dZR+AlfA@public.gmane.org>]

Hello.

On 13-03-2011 17:34, Michael Williamson wrote:

> The current davinci SPI driver, in DMA mode, is limited to 65535
> words for a single transfer.  Modify the driver by configuring a
> 3 dimensional EDMA transfer to support up to 65535x65535
> words.

> Signed-off-by: Michael Williamson<michael.williamson-wZX4cNJlHJ2sVWG7oymsAA@public.gmane.org>
[...]

> diff --git a/drivers/spi/davinci_spi.c b/drivers/spi/davinci_spi.c
> index 037ba82..411cc32 100644
> --- a/drivers/spi/davinci_spi.c
> +++ b/drivers/spi/davinci_spi.c
[...]
> @@ -599,14 +600,30 @@ static int davinci_spi_bufs(struct spi_device *spi, struct spi_transfer *t)
>   			}
>   		}
>
> +		/*
> +		 * If number of words is greater than 65535, then we need
> +		 * to configure a 3 dimension transfer.  Use the BCNTRLD
> +		 * feature to allow for transfers that aren't even multiples
> +		 * of 65535 (or any other possible b size) by first transferring
> +		 * the remainder amount then grabbing the next N blocks of
> +		 * 65535 words.
> +		 */
> +
> +		c = dspi->wcount/(SZ_64K-1);	/* N 65535 count Blocks */
> +		b = dspi->wcount-c*(SZ_64K-1);	/* Remainder */

    The driver style (and general Linux kernel style) assumes spaces around 
operators.

WRB, Sergei