Messages in this thread | | | Date | Fri, 28 Mar 2014 18:49:40 +0200 | From | Mathias Nyman <> | Subject | Re: [PATCH] usb: xhci: Correct last context entry calculation for Configure Endpoint |
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On 03/25/2014 08:42 PM, Julius Werner wrote: > The current XHCI driver recalculates the Context Entries field in the > Slot Context on every add_endpoint() and drop_endpoint() call. In the > case of drop_endpoint(), it seems to assume that the add_flags will > always contain every endpoint for the new configuration, which is not > necessarily correct if you don't make assumptions about how the USB core > uses the add_endpoint/drop_endpoint interface (add_flags only contains > endpoints that are new additions in the new configuration). > > Furthermore, EP0_FLAG is not consistently set in add_flags throughout > the lifetime of a device. This means that when all endpoints are > dropped, the Context Entries field can be set to 0 (which is invalid and > may cause a Parameter Error) or -1 (which is interpreted as 31 and > causes the driver to keep using the old, incorrect value). > > The only surefire way to set this field right is to also take all > existing endpoints into account, and to force the value to 1 (meaning > only EP0 is active) if no other endpoint is found. This patch implements > that as a single step in the final check_bandwidth() call and removes > the intermediary calculations from add_endpoint() and drop_endpoint(). >
Hi
I think this looks good in general, but before I really dig into it I'd like to know if this has triggered any problems so far? (e.g. slot context's context entries getting zeroed, or set to a smaller value than the last active endpoint context, causing trouble)
-Mathias
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