Hi Roman,
On Tue, Apr 6, 2010 at 4:39 AM, Roman Tereshonkov
<roman.tereshon...@nokia.com> wrote:
> This parameters defines the minimum number of bytes when dma is used.
>
> Signed-off-by: Roman Tereshonkov <roman.tereshon...@nokia.com>
The intent of this feature is... ? Your patch needs a better
description as to why it is needed; especially considering that it
changes common code.
But, inferring from the code that is written, I can guess what you're
trying to do, if not why. Why would spi_devices care what the minimum
size of a DMA transfer is? The SPI bus driver is in a far better
position to make that determination.
Also, since this essentially adds a new 'knob' for spi_devices to
twiddle, what is the expected behaviour for SPI bus controllers that
don't support it? Is it a required feature for spi bus drivers to
implement if they support DMA?
Cheers,
g.
> ---
> drivers/spi/spi.c | 1 +
> include/linux/spi/spi.h | 3 +++
> 2 files changed, 4 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
> index b76f246..5bf7992 100644
> --- a/drivers/spi/spi.c
> +++ b/drivers/spi/spi.c
> @@ -347,6 +347,7 @@ struct spi_device *spi_new_device(struct spi_master
> *master,
> proxy->max_speed_hz = chip->max_speed_hz;
> proxy->mode = chip->mode;
> proxy->irq = chip->irq;
> + proxy->dma_min_bytes = chip->dma_min_bytes;
> strlcpy(proxy->modalias, chip->modalias, sizeof(proxy->modalias));
> proxy->dev.platform_data = (void *) chip->platform_data;
> proxy->controller_data = chip->controller_data;
> diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h
> index 97b60b3..4e9961d 100644
> --- a/include/linux/spi/spi.h
> +++ b/include/linux/spi/spi.h
> @@ -84,6 +84,7 @@ struct spi_device {
> #define SPI_NO_CS 0x40 /* 1 dev/bus, no
> chipselect */
> #define SPI_READY 0x80 /* slave pulls low to
> pause */
> u8 bits_per_word;
> + int dma_min_bytes;
> int irq;
> void *controller_state;
> void *controller_data;
> @@ -727,6 +728,8 @@ struct spi_board_info {
> */
> u8 mode;
>
> + /* dma_min_bytes defines minimum bytes when dma is used */
> + u32 dma_min_bytes;
> /* ... may need additional spi_device chip config data here.
> * avoid stuff protocol drivers can set; but include stuff
> * needed to behave without being bound to a driver:
> --
> 1.6.2.rc1.3.g81d3f
>
>
--
Grant Likely, B.Sc., P.Eng.
Secret Lab Technologies Ltd.
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