On 8/11/22 09:25, Jyan Chou [周芷安] wrote: > Hello Adrian Hunter, > > We are now using the upstream code of EMMC CMDQ HOST CONTROLLER INTERFACE (CQHCI) DRIVER, but we found that the existing driver cannot support the limitation of Synopsys IP. > > Synopsys IP has a description on their data book " While using DMA, the host memory data buffer size and start address must not exceed 128 MB". > > I am wondering whether there is a method or patch that can fix this boundary limitation. > Thanks. > Best Regards, > Jyan Chou Hello Jyan Chou I am not clear on what the exact limitation is. The driver never uses buffers as big as 128 MB. To restrict DMA to low memory addresses a DMA mask can be used. But perhaps you mean not to cross a 128 MB boundary? Please cc your questions to the linux kernel mmc mailing list: linux-mmc@xxxxxxxxxxxxxxx because others can answer too. Regards Adrian
