On Wed, Apr 18 2018, Christian Lütke-Stetzkamp wrote:
> The current default transfer is to use DMA or not depending on the
> size of the data. The upstream driver mtk-sd uses DMA all times,
> change the standard mode here to DMA for testing, if there are any
> performance problems with DMA for small data sizes. If not, the option
> for transfer mode should be removed in the future,
>
> Signed-off-by: Christian Lütke-Stetzkamp <christian@xxxxxxxx>
> ---
> drivers/staging/mt7621-mmc/dbg.c | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/staging/mt7621-mmc/dbg.c b/drivers/staging/mt7621-mmc/dbg.c
> index 9a1809d74ea3..0d6e21557d8f 100644
> --- a/drivers/staging/mt7621-mmc/dbg.c
> +++ b/drivers/staging/mt7621-mmc/dbg.c
> @@ -67,10 +67,10 @@ u32 dma_size[4] = {
> };
>
> enum msdc_mode drv_mode[4] = {
> - MODE_SIZE_DEP, /* using DMA or not depend on the size */
> - MODE_SIZE_DEP,
> - MODE_SIZE_DEP,
> - MODE_SIZE_DEP
> + MODE_DMA, /* using DMA always */
> + MODE_DMA,
> + MODE_DMA,
> + MODE_DMA
> };
It is interesting that this table is in "dbg.c"....
Maybe this was only really important during driver development, so that
the developers could experiment and measure... there is a /proc file
which allows the size cutoff to be changed.
On my board I can only use the mmc interface for a micro SD card, so I
cannot test small transfer sizes. We might just need to bite the bullet
and discard this code. Maybe.
Thanks,
NeilBrown
>
> #if defined(MT6575_SD_DEBUG)
> --
> 2.16.1
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