Patchwork [03/12] usb-host-linux: Only enabling pipeling for output endpoints

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Submitter Hans de Goede
Date Oct. 8, 2012, 7:51 a.m.
Message ID <1349682696-3046-4-git-send-email-hdegoede@redhat.com>
Download mbox | patch
Permalink /patch/189944/
State New
Headers show

Comments

Hans de Goede - Oct. 8, 2012, 7:51 a.m.
With the upcoming input pipelining support, large input packets
may get submitted to the device, which require special handling when
the packets ends up being split again by usb-host-linux due to usbfs
limitations. The exact demands for properly handling larger split input
transfers is explained in detail in this libusb commit:
https://github.com/libusbx/libusbx/commit/ede02ba91920f9be787a7f3cd006c5a4b92b5eab

Specifically in the large comment block the commit adds. Note that IMHO
it would be better to just port usb-host-linux to libusb and let libusb
worry about such usbfs details, rather then reproducing all this code
inside host-linux.c

Note that the not proper handling of this currently already can be a problem
when used in combination with an emulated xhci controller, as that can
already submit large enough transfers to trigger this.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
---
 hw/usb/host-linux.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

Patch

diff --git a/hw/usb/host-linux.c b/hw/usb/host-linux.c
index 44f1a64..3a258b4 100644
--- a/hw/usb/host-linux.c
+++ b/hw/usb/host-linux.c
@@ -1224,7 +1224,8 @@  static int usb_linux_update_endp_table(USBHostDevice *s)
                 usb_ep_set_type(&s->dev, pid, ep, type);
                 usb_ep_set_ifnum(&s->dev, pid, ep, interface);
                 if ((s->options & (1 << USB_HOST_OPT_PIPELINE)) &&
-                    (type == USB_ENDPOINT_XFER_BULK)) {
+                    (type == USB_ENDPOINT_XFER_BULK) &&
+                    (pid == USB_TOKEN_OUT)) {
                     usb_ep_set_pipeline(&s->dev, pid, ep, true);
                 }