linux-kernel - Re: [PATCH 1/2] spi: Add DMA support for spi_flash

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Message-ID: <20160412043115.GV3351@sirena.org.uk>
Date:	Tue, 12 Apr 2016 05:31:15 +0100
From:	Mark Brown <broonie@...nel.org>
To:	Vignesh R <vigneshr@...com>
Cc:	linux-spi@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-omap@...r.kernel.org
Subject: Re: [PATCH 1/2] spi: Add DMA support for spi_flash_read()

On Tue, Apr 05, 2016 at 09:19:51AM +0530, Vignesh R wrote:

>  	mutex_lock(&master->bus_lock_mutex);
> +	if (master->dma_rx) {
> +		rx_dev = master->dma_rx->device->dev;
> +		ret = spi_map_buf(master, rx_dev, &msg->rx_sg,
> +				  msg->buf, msg->len,
> +				  DMA_FROM_DEVICE);
> +		if (ret != 0)
> +			goto  err;
> +	}

This is unconditionally DMA mapping the buffer if DMA is supported.
That's going to be common but I'm not sure it'll be universal, we need
to think of something better here.  I'm not immediately seeing what
though.  Possibly a flag...

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