In message <404E51E7.4070909 at iti.fi> you wrote: > > There is simple spi driver arch/ppc/8260_io/cpm_spi.c but i think that > one like > i2c subsystem will be much more usefull. I have been planning make one based > on i2c driver.
Arghh.... Why do you think you need all this overhead? > I am plannigg 3-layer model like in i2c or USB. interface-HW-driver in > lowest level, > then subsystem driver and then target HW driver. Like in this case > PSC_SPI-> SPI_subsystem->MMC ---->FS Remember that SPI is always very board-specific. I'm not sure that it really makes sense to create a special "SPI subsystem" - especially when you use I2C as a model (which IMHO is just a lot of overkill). > There is same problem in mpc5200 SPI and for this reason i am planning to > use PSC in SPI mode. Then i will have fifo etc. I am also considering to > use bestcom DMA. I just have heard that there is lot of problems with it > when used with I2S. What is actually causing the problems ? The design of the available (at the moment) bestcomm code. > Bestcom API library ? Should it be better to use directly bestcom HW > without library ? Do yourself a favour and use the official API. Otherwise you will end up relying on a lot of internal things that may (and will) be cahnged with the next version of the bestcomm code. > Of cource it does not give best performance but it is also wery simple > glueless > interface to cheap small low cost mass media. If we like to have full fast > MMC/SD interface then we should consider some FPGA implementation > but in most cases simpler will give enough proformace. I don't know your exact application, but it always gives me the creeps when I read the phrases "mass storage device" and "SPI bus" in the same sentence. I tend to summarize this as follows: "mass storage device" + "SPI bus" = need for redesign :-) Best regards, Wolfgang Denk -- Software Engineering: Embedded and Realtime Systems, Embedded Linux Phone: (+49)-8142-4596-87 Fax: (+49)-8142-4596-88 Email: wd at denx.de By the way, ALL software projects are done by iterative prototyping. Some companies call their prototypes "releases", that's all. ** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/
