Re: [PATCH v2 1/3] spi: add xtfpga SPI controller driver

From: Mark Brown
Date: Wed Mar 12 2014 - 08:49:27 EST


On Wed, Mar 12, 2014 at 04:21:03PM +0400, Max Filippov wrote:

> + case 16:
> + /* Bytes that should go out earlier have lower addresses,
> + * but the hardware operates with 16 bit words and transmits
> + * higher bits first. Thus data in memory is in BE order.
> + */
> + xspi->data = (xspi->data << 16) | be16_to_cpu(v);
> + xspi->data_sz += 2;
> + break;

Are you sure you need to do this byte swap? SPI words are big endian so
if you are running on a little endian processor if you are transmitting
16 bit words you should see the data getting swapped on the bus (this is
why I say you should never have more than 8 bits per word for regmap).

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