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    usb/hub: allow hubs up to 31 children · 43705251
    inaky@linux.intel.com 提交于
    Current Wireless USB host hardware (Intel i1480 for example) allows up
    to 22 devices to connect, thus bringing up the max number of children
    in the WUSB Host Controller to 22 'fake' ports. Upcoming hardware
    might raise that limit.
    
    Makes almost no difference to go to 31, as the bit arrays are
    byte-aligned (plus an extra bit in general), so 22 bits fit in 4 bytes
    as 31 do.
    
    As well, the only other array that depends on USB_MAXCHILDREN is
    'struct usb_hub->indicator'. By declaring it 'u8' instead of 'enum
    hub_led_mode', we reduce the size of each entry from 4 bytes (in i386)
    to 1, which will add as we when are doubling USB_MAXCHILDREN
    (with 16 the size of that array is 64 bytes, with 31 would be 128; by
    using u8 that goes down to 31 bytes).
    Signed-off-by: NInaky Perez-Gonzalez <inaky.perez-gonzalez@intel.com>
    Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>
    43705251
hub.h 6.3 KB