On Fri, Dec 22, 2023 at 11:29:01AM +0530, Prashanth K wrote: > On 15-12-23 06:12 pm, Greg Kroah-Hartman wrote: > > On Tue, Dec 12, 2023 at 04:55:20PM +0530, Prashanth K wrote: > > > Upstream commit bac1ec551434 ("usb: xhci: Set quirk for > > > XHCI_SG_TRB_CACHE_SIZE_QUIRK") introduced a new quirk in XHCI > > > which fixes XHC timeout, which was seen on synopsys XHCs while > > > using SG buffers. But the support for this quirk isn't present > > > in the DWC3 layer. > > > > > > We will encounter this XHCI timeout/hung issue if we run iperf > > > loopback tests using RTL8156 ethernet adaptor on DWC3 targets > > > with scatter-gather enabled. This gets resolved after enabling > > > the XHCI_SG_TRB_CACHE_SIZE_QUIRK. This patch enables it using > > > the xhci device property since its needed for DWC3 controller. > > > > > > In Synopsys DWC3 databook, > > > Table 9-3: xHCI Debug Capability Limitations > > > Chained TRBs greater than TRB cache size: The debug capability > > > driver must not create a multi-TRB TD that describes smaller > > > than a 1K packet that spreads across 8 or more TRBs on either > > > the IN TR or the OUT TR. > > > > > > Cc: <stable@xxxxxxxxxxxxxxx> > > > Signed-off-by: Prashanth K <quic_prashk@xxxxxxxxxxx> > > > > What commit id does this fix? > > > This doesn't fix any commit as such, but adds the support for > XHCI_SG_TRB_CACHE_SIZE_QUIRK (which is present in XHCI layer) to DWC3 layer. So this is a new feature? How does this fit into the stable kernel rules? > I have CC'ed stable kernel for this to be back-ported to older kernels > (#5.11). Why that specific kernel version and newer? Why not list it as documented? > > > > > --- > > > drivers/usb/dwc3/host.c | 2 ++ > > > 1 file changed, 2 insertions(+) > > > > > > diff --git a/drivers/usb/dwc3/host.c b/drivers/usb/dwc3/host.c > > > index 61f57fe5bb78..31a496233d87 100644 > > > --- a/drivers/usb/dwc3/host.c > > > +++ b/drivers/usb/dwc3/host.c > > > @@ -89,6 +89,8 @@ int dwc3_host_init(struct dwc3 *dwc) > > > memset(props, 0, sizeof(struct property_entry) * ARRAY_SIZE(props)); > > > + props[prop_idx++] = PROPERTY_ENTRY_BOOL("xhci-sg-trb-cache-size-quirk"); > > > > And this is ok if the entry is not present? > > > We are intending to use this quirk for all the dwc3 based devices since the > DWC3 XHC needs it. So you do not have this quirk yet in the kernel tree? We can't take code without any in-tree users. > If the entry is not present then we will hit stall if > certain conditions aren't met (have mentioned the condition in commit text). When will the quirk be added? To what platforms? thanks, greg k-h