Re: [PATCH RFC 2/4] mmc: host: renesas_sdhi_sys_dmac: Do not fall back to PIO

[Ulrich Hecht <uli@fpond.eu>]

> On November 22, 2019 at 7:13 AM Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com> wrote:
> 
> 
> Falling back to PIO forever is not convenience if a buffer condition
> is not match with the hardware once. So, this patch removes it.
> 
> Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
> ---
>  drivers/mmc/host/renesas_sdhi_sys_dmac.c | 35 +++++++-------------------------
>  1 file changed, 7 insertions(+), 28 deletions(-)
> 
> diff --git a/drivers/mmc/host/renesas_sdhi_sys_dmac.c b/drivers/mmc/host/renesas_sdhi_sys_dmac.c
> index 30f34a3..09137cc 100644
> --- a/drivers/mmc/host/renesas_sdhi_sys_dmac.c
> +++ b/drivers/mmc/host/renesas_sdhi_sys_dmac.c
> @@ -175,7 +175,7 @@ static void renesas_sdhi_sys_dmac_start_dma_rx(struct tmio_mmc_host *host)
>  	}
>  
>  	if (sg->length < min_len)
> -		return;
> +		goto pio;
>  
>  	/* The only sg element can be unaligned, use our bounce buffer then */
>  	if (!aligned) {
> @@ -200,23 +200,13 @@ static void renesas_sdhi_sys_dmac_start_dma_rx(struct tmio_mmc_host *host)
>  			ret = cookie;
>  		}
>  		host->dma_on = true;
> +		renesas_sdhi_sys_dmac_enable_dma(host, true);
>  	}
>  pio:
>  	if (!desc) {
> -		/* DMA failed, fall back to PIO */
>  		renesas_sdhi_sys_dmac_enable_dma(host, false);
> -		if (ret >= 0)
> -			ret = -EIO;
> -		host->chan_rx = NULL;
> -		dma_release_channel(chan);
> -		/* Free the Tx channel too */
> -		chan = host->chan_tx;
> -		if (chan) {
> -			host->chan_tx = NULL;
> -			dma_release_channel(chan);
> -		}
> -		dev_warn(&host->pdev->dev,
> -			 "DMA failed: %d, falling back to PIO\n", ret);
> +		host->dma_on = false;
> +		dev_dbg(&host->pdev->dev, "DMA failed: %d\n", ret);
>  	}
>  }
>  
> @@ -248,7 +238,7 @@ static void renesas_sdhi_sys_dmac_start_dma_tx(struct tmio_mmc_host *host)
>  	}
>  
>  	if (sg->length < min_len)
> -		return;
> +		goto pio;
>  
>  	/* The only sg element can be unaligned, use our bounce buffer then */
>  	if (!aligned) {
> @@ -281,20 +271,9 @@ static void renesas_sdhi_sys_dmac_start_dma_tx(struct tmio_mmc_host *host)
>  	}
>  pio:
>  	if (!desc) {
> -		/* DMA failed, fall back to PIO */
>  		renesas_sdhi_sys_dmac_enable_dma(host, false);
> -		if (ret >= 0)
> -			ret = -EIO;
> -		host->chan_tx = NULL;
> -		dma_release_channel(chan);
> -		/* Free the Rx channel too */
> -		chan = host->chan_rx;
> -		if (chan) {
> -			host->chan_rx = NULL;
> -			dma_release_channel(chan);
> -		}
> -		dev_warn(&host->pdev->dev,
> -			 "DMA failed: %d, falling back to PIO\n", ret);
> +		host->dma_on = false;
> +		dev_dbg(&host->pdev->dev, "DMA failed: %d\n", ret);
>  	}
>  }
>  
> -- 
> 2.7.4

Reviewed-by: Ulrich Hecht <uli+renesas@fpond.eu>

CU
Uli