On 05/10/2018 12:28 AM, NeilBrown wrote: > On Wed, May 09 2018, Boris Brezillon wrote: > >> On Fri, 27 Apr 2018 16:18:05 +1000 >> NeilBrown <[email protected]> wrote: >> >>> Hi, >>> I've labeled this an RFC because I'm really not sure about removing the >>> error path from spi_nor_write() -- maybe that really matters. But on >>> my hardware, performing multiple small spi writes to the flash seems >>> to work. >>> >>> The spi driver is drivers/staging/mt7621-spi. Possibly this needs to >>> use DMA instead of a FIFO (assuming the hardware can) - or maybe >>> drivers/spi/spi-mt65xx.c can be made to work on this hardware, though >>> that is for an ARM SOC and mt7621 is a MIPS SOC. >>> >>> I note that openwrt has similar patches: >>> >>> target/linux/generic/pending-4.14/450-mtd-spi-nor-allow-NOR-driver-to-write-fewer-bytes-th.patch >>> >>> They also change the spi driver to do a short write, rather >>> than change m25p80 to request a short write. >>> >>> Is there something horribly wrong with this? >> >> Marek, any opinion on this patch? >> > > Hi, > thanks for following up. > I have since found that I don't need this patch, though maybe others > still do(??). > My hardware can only send 36 bytes and receive 32 in a single > transaction. However I can run a sequence of transactions > to process a whole message no matter how large that message is. As > long as I keep chip-select asserted, all the slave device sees is that > the clock period isn't quite constant, and the slave shouldn't care > much about that. > When reading from flash, I found that handling large messages with > multiple hardware transactions was 50% faster than breaking the > read down into lots of 32 byte messages. > > So, I won't object if this patch is forgotten. Thanks for > your time anyway.
Nice, which hardware is that ? -- Best regards, Marek Vasut
