linux-usb-owner@xxxxxxxxxxxxxxx wrote: > On Mon, Feb 25, 2013 at 01:42:44PM +0200, Felipe Balbi wrote: >> HI, >> >> On Mon, Feb 25, 2013 at 07:33:23PM +0800, Soar Hung wrote: >>>> What's the actual issue here ? Can you explain to me Sarah ? >>>> This may be a known issue regarding this particular host >>>> controller and if it is, there might already be workarounds >>>> available. >>> >>> I copy the previous content and try to make it more clear. >>> >>> When calling usb_reset_and_verify_device, hcd issue a reset command. >>> The reset device command make the endpoint state disabled without >>> releaseing the bandwidth. >>> >>> After reset is done, the HCD try to reconfigure the device to >>> previous active config by usb_hcd_alloc_bandwidth. >>> The HCD does such thing by modifying drop and add flag in input >>> context, and issue configure endpoint command to comoplete the >>> operation. >>> >>> When executing drop_endpoint, the endpoint is already in the >>> disabled state. This behavior is correct according to the spec. And >>> the HC will not evaluate drop flag of disable endpoint,too. >> >>> As a result, the HC can not drop the endpoint to release the >>> bandwidth. >> >> But if the endpoint is already dropped, why hasn't bandwidth >> allocation being released too ? Sarah ? > > I think we're talking past each other. :) Soar, what > bandwidth allocation resources are you talking about? In the > xHC hardware, or in the xHCI driver? I've been talking about > resources in the hardware only, but I want to confirm we're talking > about the same thing. > As my understading, the bandwidth is managed by xHC(hardware), The HCD(driver) only use xHCI input context and command to tell xHC do something. > As I understand it, the Reset Device command should drop all > bandwidth allocated within the xHC hardware. Then we go back > and re-add the endpoints, setting only the add flag in the > input context. As Soar mentioned, this is spec-compliant, > but the host eventually gives an out-of-bandwidth completion > code for the Configure Endpoint command. > Now I understand why this is QUIRK not a fix. Spec 4.6.11 says the xHC shall release bandwidth automatically when doing reset device command. Best regards, Soar -- 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
