Thank you wolfgang. I see also in cpu/nios an implementation of the spi core, it uses volatiles variables to access hardware, so it will not work. Nevertheless the implementation is correct. I'm adding sd access by spi protocol to u-boot, so i created a new file called mmc_spi.c in cpu/nios2. I faced many problems. I just want to have access to the fat partition, then i wrote mmc_get_dev and mmc_read_block but i need to initialize the card so i implemented mmc_init (which add mmc command) and i don't want to write mmc_read/write/2info. Should i implement those functions?. In the other hand, should i use spi_xfer() to do spi transactions?. Regards, Ivan Llopard.
2009/2/5 Wolfgang Denk wd@denx.de
Dear ivanchuklist ivanchu,
In message 51a313240902050730k4f03247etc73ac5579c1f7154@mail.gmail.com you wrote:
I use readl() or writel() to access the hardware but i found a compiler
flag
that bypass the cache for all volatile variables, it uses io versions of load/store functions. So, what should i do, make use of write/read
functions
or insert this flag in the makefile?.
Please continue to use the I/O accessor functions. Your specific compiler version may understand such an option, but don't expect that any other compiler or architecture provides the same - so better stay portable and use what was designed exactly for this purpose.
Best regards,
Wolfgang Denk
-- DENX Software Engineering GmbH, MD: Wolfgang Denk & Detlev Zundel HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd@denx.de Perl itself is usually pretty good about telling you what you shouldn't do. :-) - Larry Wall in 11091@jpl-devvax.JPL.NASA.GOV