On 10.3.2020 20.34, Alan Cooper wrote: > On Mon, Mar 9, 2020 at 8:19 AM Mathias Nyman > <mathias.nyman@xxxxxxxxxxxxxxx> wrote: >> >> On 6.3.2020 18.06, Al Cooper wrote: >>> Unable to complete the enumeration of a USB TV Tuner device. >>> >>> Per XHCI spec (4.6.5), the EP state field of the input context shall >>> be cleared for a set address command. In the special case of an FS >>> device that has "MaxPacketSize0 = 8", the Linux XHCI driver does >>> not do this before evaluating the context. With an XHCI controller >>> that checks the EP state field for parameter context error this >>> causes a problem in cases such as the device getting reset again >>> after enumeration. >>> >>> When that field is cleared, the problem does not occur. >>> >>> This was found and fixed by Sasi Kumar. >>> >>> Signed-off-by: Al Cooper <alcooperx@xxxxxxxxx> >>> --- >>> drivers/usb/host/xhci.c | 1 + >>> 1 file changed, 1 insertion(+) >>> >>> diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c >>> index dbac0fa9748d..5f034e143082 100644 >>> --- a/drivers/usb/host/xhci.c >>> +++ b/drivers/usb/host/xhci.c >>> @@ -1428,6 +1428,7 @@ static int xhci_check_maxpacket(struct xhci_hcd *xhci, unsigned int slot_id, >>> xhci->devs[slot_id]->out_ctx, ep_index); >>> >>> ep_ctx = xhci_get_ep_ctx(xhci, command->in_ctx, ep_index); >>> + ep_ctx->ep_info &= cpu_to_le32(~EP_STATE_MASK);/* must clear */ >>> ep_ctx->ep_info2 &= cpu_to_le32(~MAX_PACKET_MASK); >>> ep_ctx->ep_info2 |= cpu_to_le32(MAX_PACKET(max_packet_size)); >>> >>> >> >> Thanks, nice catch. >> >> If you agree I'd like to change the the subject of this patch to something like: >> "xhci: Fix enumeration issue when setting actual max packet size for FS devices" >> >> While looking at this it seems that the current EP_STATE_MASK is not correct either. >> It should be 0x7 instead of 0xf. >> > > Agree on both points. > Should I re-send a v2? > No need, I can make those changes -Mathias
