• Douglas Anderson's avatar
    usb: dwc2: Avoid double-reset at boot time · 0fe239bc
    Douglas Anderson authored
    In (usb: dwc2: reset dwc2 core before dwc2_get_hwparams()) we added an
    extra reset to the probe path for the dwc2 USB controllers.  This
    allowed proper detection of parameters even if the firmware had already
    used the USB part.
    
    Unfortunately, this extra reset is quite slow and is affecting boot
    speed.  We can avoid the double-reset by skipping the extra reset that
    would happen just after the one we added.  Logic that explains why this
    is safe:
    
    * As of the CL mentioned above, we now always call dwc2_core_reset() in
      dwc2_driver_probe() before dwc2_hcd_init().
    
    * The only caller of dwc2_hcd_init() is dwc2_driver_probe(), so we're
      guaranteed that dwc2_core_reset() was called before dwc2_hdc_init().
    
    * dwc2_hdc_init() is the only caller that passes an irq other than -1 to
      dwc2_core_init().  Thus if dwc2_core_init() is called with an irq
      other than -1 we're guaranteed that dwc2_core_reset was called before
      dwc2_core_init().
    
    ...this allows us to remove the dwc2_core_reset() in dwc2_core_init() if
    irq is not < 0.
    
    Note that since "irq" wasn't used in the function dwc2_core_init()
    anyway and since select_phy was always set at exactly the same times we
    could avoid the reset, we remove "irq" and rename "select_phy" to
    "initial_setup" and adjust the callers accordingly.
    Signed-off-by: default avatarDouglas Anderson <dianders@chromium.org>
    Signed-off-by: default avatarJohn Youn <johnyoun@synopsys.com>
    Signed-off-by: default avatarFelipe Balbi <balbi@ti.com>
    0fe239bc
hcd.c 92 KB