[PATCH v2 1/3] spi: implemented driver for Cirrus EP93xx SPI controller

[Martin Guy]

On 4/10/10, Mika Westerberg <mika.westerberg at iki.fi> wrote:
>  Can you try following with your devices?

Woo, nice one!
Same CPU usage (~57%) same throughput (315kb/s) and it's much more
elegant. :) Just using repeated interrupts to handle the last 4 words
instead of the nasty busy-wait loops seems fairer to other interrupts
too!

You can make it even smaller be removing some redundant checks
deriving from the fact that it's synchronous, so N writes always cause
N reads:

>         if (espi->tx == 0 && espi->rx == 0)
>                 espi->fifo_level = 0;

can be

         if (espi->tx == 0)
                 espi->fifo_level = 0;

,

>         while ((ep93xx_spi_read_u8(espi, SSPSR) & SSPSR_RNE) &&
>                 espi->rx < t->len) {

         while ((ep93xx_spi_read_u8(espi, SSPSR) & SSPSR_RNE)) {

and

>         /* is transfer finished? */
>         if (espi->tx == t->len && espi->rx == t->len) {

         if (espi->rx == t->len) {

Cheers!

    M