mirror of https://gitee.com/openkylin/linux.git
55c527187c
This patch (as609) changes the way we keep track of power budgeting for USB hubs and devices, and it updates the choose_configuration routine to take this information into account. (This is something we should have been doing all along.) A new field in struct usb_device holds the amount of bus current available from the upstream port, and the usb_hub structure keeps track of the current available for each downstream port. Two new rules for configuration selection are added: Don't select a self-powered configuration when only bus power is available. Don't select a configuration requiring more bus power than is available. However the first rule is #if-ed out, because I found that the internal hub in my HP USB keyboard claims that its only configuration is self-powered. The rule would prevent the configuration from being chosen, leaving the hub & keyboard unconfigured. Since similar descriptor errors may turn out to be fairly common, it seemed wise not to include a rule that would break automatic configuration unnecessarily for such devices. The second rule may also trigger unnecessarily, although this should be less common. More likely it will annoy people by sometimes failing to accept configurations that should never have been chosen in the first place. The patch also changes usbcore's reaction when no configuration is suitable. Instead of raising an error and rejecting the device, now the core will simply leave the device unconfigured. People can always work around such problems by installing configurations manually through sysfs. Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de> |
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