Lei Wen schrieb: > On Mon, Sep 6, 2010 at 5:23 PM, Reinhard Meyer <u-b...@emk-elektronik.de> > wrote: >> Dear Lei Wen, >>> As mmc host limitation, the max number of block in one go
You already write it's a HOST limitation. >>> should be limited to 65535, and the max buffer size should >>> not excceed 512k bytes. Which would limit the #blocks to 1024 (assuming a 512 byte blocks) >> Where does this limitation supposedly come from? > > This limitation comes from the SD/MMC sepc. You could find one and > check the 0x6 offset register(BLOCK COUNT REGISTER). This might refer to certain HOST controllers, but not to Cards! > You could get that register is only 16bit width and only cound contain > the 65535 block. > > This register is only validate for multi-operation, like multi-read or > multi-write command. Hmm, CMD25 states: "Continuously writes blocks of data until a STOP_TRANSMISSION follows." So the Card itself does not limit the number of blocks written in one go. I do not mind the transfer to be split into chunks if required by some hosts, but the "number of blocks in a go" should be configurable. And you still do not explain why the buffer size shall be limited to 512KB? Best Regards, Reinhard _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot