[U-Boot] [PATCH 3/7] eSPI: add eSPI controller support

[Mike Frysinger]

On Thursday 27 August 2009 02:59:34 Hu Mingkai-B21284 wrote:
> From: Mike Frysinger [mailto:vapier at gentoo.org]
> > On Thursday 27 August 2009 02:27:30 Hu Mingkai-B21284 wrote:
> > > > but what if you dont know the length of the transaction ahead of
> > > > time ?  if you look at the spi flash framework, it'll write a few
> > > > bytes (like the opcode to read the status
> > > > register) and then it'll just keep reading 1 byte at a time (polling
> > > > the status register).  there is no way of knowing the length ahead
> > > > of time.  most of the SPI code in u-boot operates this way.
> > >
> > > So the driver use the length passed by SPI flash read function.
> > > If the length is greater than the max value that is limited by the
> > > transaction length register's bitfiled, the driver couldn't read
> > > anything.
> >
> > the length used by the first read covers just the length of
> > the opcode, not any of the data returned by the part
> >
> > as long as your driver rejects all of these things, it'll be
> > detected at runtime and it should be fine to merge -mike
>
> So the driver combine the opcode length and the data length together,
> then pass to spi_xfer(for eSPI) . When return the read results, skip the
> first opcode length bytes.

you dont get it ... there is no data length.  the code does:

spi_write(~3 bytes for opcode, BEGIN flag);
while (1) {
	spi_read(read 1 data byte);
	check_result();
}
end_spi_transaction();

there is no "data length" which means your controller cannot support the SPI 
flash framework
-mike
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