[PATCHv2 00/10] Add memory mapped support for ti qspi, m25p80 serial flash.

[Sourav Poddar]

Hi Mark,
On Tuesday 10 December 2013 11:59 PM, Mark Brown wrote:
> On Tue, Dec 10, 2013 at 07:22:10PM +0100, Marek Vasut wrote:
>> On Tuesday, December 10, 2013 at 05:11:43 PM, Mark Brown wrote:
>>> There is some stuff that pushes up into the controller in that while the
>>> device is in memory mapped mode as far as I can tell it's not safe to do
>>> other accesses so if someone's put more than one device on the SPI bus
>>> we need to handle interactions there.
>> OK, so it's either-or . That seems OK, you might want to have two drivers for
>> this ip block, one to handle it as a SPI block and one to handle it as a SPI-NOR
>> block. ... that is of course, if these two modes can't work together.
> Or the client disables the memory map when it's not actively being used
> and the stops other transfers starting while the mapping is in place.
> I'd expect we'll have to cope with shared use at some point, hardware
> engineers will probably build such systems.
So, what I am doing here in my code is that whenever I desired to use a
mmap operations I do a

a. flash_lock()
b. wait till the previous erase/write is finished
c. 'get_buf' which in turn does
       - get_sync
       - enable memory mapped

d. memcpy
e. 'put_buf' which in turn does
            - disable memory mapped
            - put_sync


f. flash_unlock

Do you see any point missing here?

On your comment about disabling transfers while doing a mmap..
Are you suggesting on having a check in qspi transfer api something like 
this..

transfer_one_message {
  if (mmap)
      return -EINPROGRESS;
}

Where mmap can be set/unset in get_buf/put_buf respectively.