Re: [PATCH v3] spi: core: Validate length of the transfers in message

[Atsushi Nemoto <anemo@mba.ocn.ne.jp>]

On Thu, 20 Feb 2014 12:02:08 +0200, "Ivan T. Ivanov" <iivanov@mm-sol.com> wrote:
> SPI transfer length should be multiple of SPI word size,
> where SPI word size should be power-of-two multiple
...
> +		n_words = xfer->len / w_size;
> +		/* No partial transfers accepted */
> +		if (!n_words || xfer->len % w_size)
> +			return -EINVAL;

Is xfer->len == 0 invalid?
Long time ago I have fixed atmel spi driver to support zero length
transfer (commit 06719814 atmel_spi: support zero length transfer).

According to Documentation/spi/spi-summary, zeto length transfer seems
valid.

      + optionally defining short delays after transfers ... using
        the spi_transfer.delay_usecs setting (this delay can be the
        only protocol effect, if the buffer length is zero);

---
Atsushi Nemoto