On Thu, Nov 23, 2017 at 04:53:41PM +0800, Kai Heng Feng wrote: > > > On 23 Nov 2017, at 3:58 PM, Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx> wrote: > > > > On Thu, Nov 23, 2017 at 01:38:38AM -0500, Kai-Heng Feng wrote: > >> r8153 on Dell TB dock corrupts rx packets. > >> > >> The root cause is not found yet, but disabling rx checksumming can > >> workaround the issue. We can use this connection to decide if it's > >> a Dell TB dock: > >> Realtek r8153 <-> SMSC hub <-> ASMedia XHCI controller > >> > >> BugLink: https://bugs.launchpad.net/bugs/1729674 > >> Cc: Mario Limonciello <mario.limonciello@xxxxxxxx> > >> Signed-off-by: Kai-Heng Feng <kai.heng.feng@xxxxxxxxxxxxx> > >> --- > >> drivers/net/usb/r8152.c | 33 ++++++++++++++++++++++++++++++++- > >> 1 file changed, 32 insertions(+), 1 deletion(-) > >> > >> diff --git a/drivers/net/usb/r8152.c b/drivers/net/usb/r8152.c > >> index d51d9abf7986..58b80b5e7803 100644 > >> --- a/drivers/net/usb/r8152.c > >> +++ b/drivers/net/usb/r8152.c > >> @@ -27,6 +27,8 @@ > >> #include <linux/usb/cdc.h> > >> #include <linux/suspend.h> > >> #include <linux/acpi.h> > >> +#include <linux/pci.h> > >> +#include <linux/usb/hcd.h> > >> > >> /* Information for net-next */ > >> #define NETNEXT_VERSION "09" > >> @@ -5135,6 +5137,35 @@ static u8 rtl_get_version(struct usb_interface *intf) > >> return version; > >> } > >> > >> +/* Ethernet on Dell TB 15/16 dock is connected this way: > >> + * Realtek r8153 <-> SMSC hub <-> ASMedia XHCI controller > >> + * We use this connection to make sure r8153 is on the Dell TB dock. > >> + */ > >> +static bool check_dell_tb_dock(struct usb_device *udev) > >> +{ > >> + struct usb_device *hub = udev->parent; > >> + struct usb_device *root_hub; > >> + struct pci_dev *controller; > >> + > >> + if (!hub) > >> + return false; > >> + > >> + if (!(le16_to_cpu(hub->descriptor.idVendor) == 0x0424 && > >> + le16_to_cpu(hub->descriptor.idProduct) == 0x5537)) > >> + return false; > >> + > >> + root_hub = hub->parent; > >> + if (!root_hub || root_hub->parent) > >> + return false; > >> + > >> + controller = to_pci_dev(bus_to_hcd(root_hub->bus)->self.controller); > > > > That's a very scary, and dangerous, cast. You can not ever be sure that > > the hub really is a "root hub" like this. > > What I want to do here is to finding this connection: > Realtek r8153 <-> SMSC hub (USD ID: 0424:5537) <-> > ASMedia XHCI controller (PCI ID: 1b21:1142). > > Is there a safer way to do this? Nope! You can't do that at all from within a USB driver, sorry. As you really should not care at all :) > >> + if (controller->vendor == 0x1b21 && controller->device == 0x1142) > >> + return true; > > > > Why can't you just look at the USB device itself and go off of a quirk > > in it? Something like a version or string or something else? > > I have a r8153 <-> USB 3.0 dongle which work just fine. I can’t find any > information to differentiate them. Hence I want to use the connection to > identify if r8153 is on a Dell TB dock. Are you sure there is nothing different in the version or release number of the device? 'lsusb -v' shows the exact same information for both devices? > > This sounds like a USB host controller issue, not a USB device issue, > > can't we fix the "real" problem here instead of this crazy work-around? > > Yes. From what I know, ASMedia is working on it, but not sure how long it > will take. In the meantime, I’d like to workaround this issue for the users. Again, it's a host controller bug, it should be fixed there, don't try to paper over the real issue in different individual drivers. I think I've seen various patches on the linux-usb list for this controller already, have you tried them? > > Odds are any device plugged into the hub should have the same issue, > > right? > > Actually no. > I just plugged r8153 dongle into the same hub, surprisingly the issue > doesn’t happen in this scenario. Then something seems to be wrong with the device itself, as that would be the same exact electrical/logical path, right? thanks, greg k-h -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
