Hi Stefan, On Fri, Jul 17, 2020 at 6:11 PM Stefan Roese <[email protected]> wrote: > > Hi Bin, > > On 17.07.20 12:09, Bin Meng wrote: > > Hi Stefan, > > > > On Fri, Jul 17, 2020 at 6:04 PM Stefan Roese <[email protected]> wrote: > >> > >> On 17.07.20 07:24, Bin Meng wrote: > >>> Hi Stefan, > >>> > >>> On Thu, Jul 2, 2020 at 4:47 PM Stefan Roese <[email protected]> wrote: > >>>> > >>>> xhci_writeq() makes the CPU->LE swapping only when addressing registers > >>>> in the xHCI controller address range and not in the local memory (RAM). > >>> > >>> Is the above behavior exposed by the MIPS platform's writel()? > >> > >> Not sure what you mean with this. Without this patch, xhci_writeq() > >> will not swap on Octeon MIPS, as the destination address is located > >> in local memory (DDR). > > > > I wonder why xhci_writeq() does not swap? Is this due to the writel() > > implementation on Octeon MIPS? > > Ah, okay. Please see my comment below for this. Here again: > > BTW: The Octeon MIPS writel will swap to little-endian, when the > location is in the xHCI controller address space (and PCI etc). This > support for selective swapping is not pushed into mainline yet. I > will send it in some follow up patches. > > So to answer your question: writel will not swap when addressing > local memory.
Thanks. That explains. > > >> Using the xhci_read/write accessor functions > >> should be restricted to accessing the controller registers. > > > > Yes, this is the supposed usage that xhci_read/write should be called > > to operate on xHCI registers. However my question was why > > xhci_read/write does not swap even it is called on memory space, hence > > the writel() question. > > Regards, Bin
