Re: [PATCH 27/30] staging: mt7621-mmc: Always use linked DMA mode

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On Sun, Apr 29 2018, Christian Lütke-Stetzkamp wrote:

> Current code uses linked DMA mode only when there is more than one
> entry in the scatterlist. But the overhead of the linked DMA is very
> small, so the code is easier when only using linked DMA and this is
> also the way, the upstream driver mtk-sd handles it.
>
> Signed-off-by: Christian Lütke-Stetzkamp <christian@xxxxxxxx>
> ---
>  drivers/staging/mt7621-mmc/sd.c | 5 +----
>  1 file changed, 1 insertion(+), 4 deletions(-)
>
> diff --git a/drivers/staging/mt7621-mmc/sd.c b/drivers/staging/mt7621-mmc/sd.c
> index b51a4b156605..706eab4e1237 100644
> --- a/drivers/staging/mt7621-mmc/sd.c
> +++ b/drivers/staging/mt7621-mmc/sd.c
> @@ -1169,10 +1169,7 @@ static void msdc_dma_setup(struct msdc_host *host, struct msdc_dma *dma,
>  	dma->sg = sg;
>  	dma->sglen = sglen;
>  
> -	if (sglen == 1 && sg_dma_len(sg) <= MAX_DMA_CNT)
> -		dma->mode = MSDC_MODE_DMA_BASIC;
> -	else
> -		dma->mode = MSDC_MODE_DMA_DESC;
> +	dma->mode = MSDC_MODE_DMA_DESC;

So now you can remove the MSDC_MODE_DMA_BASIC code, and remove the
switch statement which chooses it, and the name itself.

Lots of good cleanups happening here, thanks.

NeilBrown


>  
>  	N_MSG(DMA, "DMA mode<%d> sglen<%d> xfersz<%d>", dma->mode, dma->sglen,
>  	      host->xfer_size);
> -- 
> 2.16.1

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