On Monday 22 June 2009, Alek Du wrote: > > > 2. If HCD has local SRAM, the sw part will consume it too, and it won't > > > bring any benefit. > > > > Same point can be made for having the 64-bit pointer fields. > > Will you be making those more optional in later patches? > > David, I missed point here, can you elaborate more here? On 32-bit systems, where EHCI doesn't support 64-bit DMA, the following memory is wasted: ehci_qtd.hw_buf_hi[5] ... 20 bytes ehci_qh.hw_buf_hi[5] ... 20 bytes ehci_itd.hw_bufp_hi[7] ... 28 bytes ehci_sid.hw_buf_hi[2] ... 8 bytes In the same way that having the "sw part" in that local SRAM just wastes memory, so does having those fields in that small SRAM area. (I don't know the hardware you're thinking of, but similar full-speed designs have only had 32KB of SRAM.) -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
