On Mon, May 6, 2019 at 10:19 PM Mathias Nyman <mathias.nyman@xxxxxxxxxxxxxxx> wrote: > > On 2.5.2019 7.56, Nicolas Boichat wrote: > > Some XHCI controllers may not have any USB 3.0 port, in this case, it > > is not useful to create add hcd->shared_hcd, which has 2 main > > downsides: > > - A useless USB 3.0 root hub is created. > > - A warning is thrown on boot: > > hub 2-0:1.0: config failed, hub doesn't have any ports! (err -19) > > > > The change is mostly about checking if hcd->shared_hcd is NULL before > > accessing it. The one special case is in xhci_run, where we need to > > call xhci_run_finished immediately, if there is no secondary hcd. > > To me it looks like this creates an controller starting issue for > xHC hardware that have both usb2 and usb3 ports. > > When we have usb3 ports xhci->shared_hcd is not set yet when xhci_run is called > the first time. We will end up starting the xHC before properly setting up the secondary hcd. > > See further down for details Thanks Mathias and Chunfeng, I need to test this on platforms that actually support USB 3.0 (both PCI and MTK), as you both highlighted, there might be issues. I'll do that a spin a v2. It might take a while though (this is not a very critical issue). > > > > Signed-off-by: Nicolas Boichat <drinkcat@xxxxxxxxxxxx> > > --- > > > > This is a respin of https://lore.kernel.org/patchwork/patch/863993/, > > hopefully addressing the comments there. Note that I dropped the change > > in xhci-plat.c, as I do not have a device to test it, but made a > > similar change in xhci-mtk.c, in the next patch. > > > > (the @apm.com addresses seem to bounce, so I added some > > @amperecomputing.com instead, if somebody there can track back the > > original issue, I'm happy to provide a patch for xhci-plat.c as well) > > > > drivers/usb/host/xhci-hub.c | 7 ++++-- > > drivers/usb/host/xhci.c | 45 +++++++++++++++++++++++++++---------- > > 2 files changed, 38 insertions(+), 14 deletions(-) > > > > ... > > > @@ -698,6 +703,10 @@ int xhci_run(struct usb_hcd *hcd) > > > > xhci_debugfs_init(xhci); > > > > + /* There is no secondary HCD, start the host controller immediately. */ > > + if (!xhci->shared_hcd) > > + return xhci_run_finished(xhci); > > + > > PCI xHC controllers with both usb2 and usb3 ports will be started before usb3 parts are properly set up. > > xhci_pci_probe() > usb_hcd_pci_probe() > usb_add_hcd() > hcd->driver->start(hcd) // .start = xhci_run > xhci_run() > if (!xhci->shared_hcd) // TRUE as xhci->shared_hcd is not yet set, > return xhci_run_finished(xhci) // starting controller too early here > xhci->shared_hcd = usb_create_shared_hcd() // now xhci->shared_hcd is set. > > -Mathias
