W dniu 31.05.2023 o 17:27, Peter Maydell pisze:
On Wed, 31 May 2023 at 15:58, Graeme Gregory <gra...@xora.org.uk> wrote:
On Wed, May 31, 2023 at 03:02:29PM +0800, wangyuquan1...@phytium.com.cn wrote:
From: Yuquan Wang <wangyuquan1...@phytium.com.cn>
The current sbsa-ref cannot use EHCI controller which is only
able to do 32-bit DMA, since sbsa-ref doesn't have RAM above 4GB.
Hence, this uses XHCI to provide a usb controller with 64-bit
DMA capablity instead of EHCI.
Should this be below 4G?
It would be pretty disruptive to try to rearrange the memory
map to put RAM below 4GB at this point, though in theory it's
possible I guess. (I have a vague recollection that there was
some reason the RAM was all put above 4GB, but can't find
anything about that in my email archives. Perhaps Leif remembers?)
I thought that memory starts at 40bit was to not use Cortex-A53 cpu with
sbsa-ref. Nowadays it also removed Cortex-A76.
Looking back at the archives, it seems we discussed XHCI vs
EHCI when the sbsa-ref board went in, and the conclusion was
that XHCI would be better. But there wasn't a sysbus XHCI device
at that point, so we ended up committing the sbsa-ref board
with EHCI and a plan to switch to XHCI when the sysbus-xhci
device was done, which we then forgot about:
https://mail.gnu.org/archive/html/qemu-arm/2018-11/msg00638.html
Moving from EHCI to XHCI on sysbus requires also firmware changes.
Or we can just add "qemu-xhci" pcie card and have USB running.
