On Sun, Jan 15, 2012 at 10:10 AM, Matthias Fuchs matthias.fuchs@esd.eu wrote:
That's what I also tried. But from the ref manual I got no idea. When we do not find a hy to deassert the chip select manually, we cannot avoid this read.
I was assuming that the chip select deassertion was correctly being handled by the mxs_spi_end_xfer function.
This function handles the LOCK_CS and IGNORE_CRC bits that are responsible for chip select assertion/deassertion.
From the MX28 Reference Manual:
"IGNORE_CRC bit: In SPI/SSI modes: When set to 1, deassert the chip select (SSn) pin after the command is executed."
Then I tought that mxs_spi_end_xfer should be also called in the case where bitlen==0. In current code this does not happen.
It seems that the mainline linux only implements a GPIO based SPI driver. So we cannot take it for reference.
There is no mxs spi driver in the mainline kernel yet.