[GIT PULL] mtd: spi-nor: Changes for 4.11

[Mark Brown]

On Wed, Feb 08, 2017 at 11:09:39AM -0800, Brian Norris wrote:

> But one question: *why* exactly is the transfer or message limit so
> fixed? If a SPI controller allows manual control over the CS line, then
> why would anybody care if a sequence of data gets split up into multiple
> HW sequences (e.g., for a long spi_transfer, why can't we split it into
> 2 sub-transfers, while keeping the CS asserted?).

Not every device will provide software control of the chip select line
so it's possible you might hit limits there.  If a device does allow
software control then yes, we should be handling this transparently in
the core and splitting up longer transfers into chunks the device can
handle and in fact this is already done in spi_split_transfers_maxsize(). 

We're missing masking that out in spi_max_transfer_size() though so
clients won't know if we can handle things, it's overly conservative.
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