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    68d2956a
    USB: ehci-dbgp: errata for EHCI debug/host controller synchronization · 68d2956a
    Jason Wessel authored
    
    On some EHCI debug controllers after the host controller driver is
    activated, the debug controller will occasionally fail to submit a
    bulk write URB.  On controllers that exhibit this behavior a dummy
    bulk write must get submitted to resynchronize the device.
    
    The "dummy bulk write" does not get received by the host attached to
    the other end of the usb debug device.  The usb debug device simply
    acknowledges the "dummy bulk write" and returns to a usable state.
    
    The behavior, without this patch is that you see missing text from a
    complete kernel boot when using the keep option to the earlyprintk
    kernel argument.
    
    Signed-off-by: default avatarJason Wessel <jason.wessel@windriver.com>
    Cc: Ingo Molnar <mingo@elte.hu>
    Cc: Andrew Morton <akpm@linux-foundation.org>
    Cc: Yinghai Lu <yinghai@kernel.org>
    Cc: "Eric W. Biederman" <ebiederm@xmission.com>
    Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
    68d2956a
    History
    USB: ehci-dbgp: errata for EHCI debug/host controller synchronization
    Jason Wessel authored
    
    On some EHCI debug controllers after the host controller driver is
    activated, the debug controller will occasionally fail to submit a
    bulk write URB.  On controllers that exhibit this behavior a dummy
    bulk write must get submitted to resynchronize the device.
    
    The "dummy bulk write" does not get received by the host attached to
    the other end of the usb debug device.  The usb debug device simply
    acknowledges the "dummy bulk write" and returns to a usable state.
    
    The behavior, without this patch is that you see missing text from a
    complete kernel boot when using the keep option to the earlyprintk
    kernel argument.
    
    Signed-off-by: default avatarJason Wessel <jason.wessel@windriver.com>
    Cc: Ingo Molnar <mingo@elte.hu>
    Cc: Andrew Morton <akpm@linux-foundation.org>
    Cc: Yinghai Lu <yinghai@kernel.org>
    Cc: "Eric W. Biederman" <ebiederm@xmission.com>
    Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>