Re: [PATCH] spi: pxa2xx: use DMA by default if supported

[Robert Jarzmik <robert.jarzmik-GANU6spQydw@public.gmane.org>]

Dan O'Donovan <dan-M3NBUjLqch7QT0dZR+AlfA@public.gmane.org> writes:

Let me add Jarkko and Mika to the review, they were active in the driver's DMA
area lately.

Cheers.

--
Robert

[1] Dan's patch
> Currently, even if the PXA2xx SPI master supports DMA, it won't be
> enabled unless (i) the slave device is enumerated through ACPI, or
> (ii) the slave device is registered with board-specific
> controller_data specified.  Even then, there isn't a field in the
> controller_data that explicitly enables dma - it just gets enabled
> if the master supports it and controller_data is non-NULL.
>
> This means that drivers which register SPI devices on a bus without
> awareness of this controller cannot avail of DMA performance gains.
>
> This patch allows DMA transfers to be used if supported.
>
> Signed-off-by: Dan O'Donovan <dan-M3NBUjLqch7QT0dZR+AlfA@public.gmane.org>
> ---
>  drivers/spi/spi-pxa2xx.c | 10 +---------
>  1 file changed, 1 insertion(+), 9 deletions(-)
>
> diff --git a/drivers/spi/spi-pxa2xx.c b/drivers/spi/spi-pxa2xx.c
> index fe07c05..27e0307 100644
> --- a/drivers/spi/spi-pxa2xx.c
> +++ b/drivers/spi/spi-pxa2xx.c
> @@ -1240,7 +1240,7 @@ static int setup(struct spi_device *spi)
>  			chip->frm = spi->chip_select;
>  		} else
>  			chip->gpio_cs = -1;
> -		chip->enable_dma = 0;
> +		chip->enable_dma = drv_data->master_info->enable_dma;
>  		chip->timeout = TIMOUT_DFLT;
>  	}
>  
> @@ -1259,17 +1259,9 @@ static int setup(struct spi_device *spi)
>  			tx_hi_thres = chip_info->tx_hi_threshold;
>  		if (chip_info->rx_threshold)
>  			rx_thres = chip_info->rx_threshold;
> -		chip->enable_dma = drv_data->master_info->enable_dma;
>  		chip->dma_threshold = 0;
>  		if (chip_info->enable_loopback)
>  			chip->cr1 = SSCR1_LBM;
> -	} else if (ACPI_HANDLE(&spi->dev)) {
> -		/*
> -		 * Slave devices enumerated from ACPI namespace don't
> -		 * usually have chip_info but we still might want to use
> -		 * DMA with them.
> -		 */
> -		chip->enable_dma = drv_data->master_info->enable_dma;
>  	}
>  
>  	chip->lpss_rx_threshold = SSIRF_RxThresh(rx_thres);
--
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