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usb: dwc2: Avoid double-reset at boot time

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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: Douglas Anderson <dianders@chromium.org>
Signed-off-by: John Youn <johnyoun@synopsys.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>
This commit is contained in:
Douglas Anderson
2015-12-17 11:14:40 -08:00
committed by Felipe Balbi
parent cebfdbf329
commit 0fe239bc19
3 changed files with 22 additions and 15 deletions
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6
drivers/usb/dwc2/hcd.c
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@@ -1420,7 +1420,7 @@ static void dwc2_conn_id_status_change(struct work_struct *work)
dev_err(hsotg->dev,
"Connection id status change timed out\n");
hsotg->op_state = OTG_STATE_B_PERIPHERAL;
dwc2_core_init(hsotg, false, -1);
dwc2_core_init(hsotg, false);
dwc2_enable_global_interrupts(hsotg);
spin_lock_irqsave(&hsotg->lock, flags);
dwc2_hsotg_core_init_disconnected(hsotg, false);
@@ -1443,7 +1443,7 @@ static void dwc2_conn_id_status_change(struct work_struct *work)
hsotg->op_state = OTG_STATE_A_HOST;
/* Initialize the Core for Host mode */
dwc2_core_init(hsotg, false, -1);
dwc2_core_init(hsotg, false);
dwc2_enable_global_interrupts(hsotg);
dwc2_hcd_start(hsotg);
}
@@ -3120,7 +3120,7 @@ int dwc2_hcd_init(struct dwc2_hsotg *hsotg, int irq)
dwc2_disable_global_interrupts(hsotg);
/* Initialize the DWC_otg core, and select the Phy type */
retval = dwc2_core_init(hsotg, true, irq);
retval = dwc2_core_init(hsotg, true);
if (retval)
goto error2;