diff mbox series

[v4,2/2] usb: dwc3: core: defer probe on ulpi_read_id timeout

Message ID 20221120153704.9090-3-ftoth@exalondelft.nl
State New
Headers
Series usb: dwc3: core: defer probe on ulpi_read_id timeout |

Commit Message

Ferry Toth Nov. 20, 2022, 3:37 p.m. UTC 
  Since commit 0f0101719138 ("usb: dwc3: Don't switch OTG -> peripheral if extcon is present"),
Dual Role support on Intel Merrifield platform broke due to rearranging
the call to dwc3_get_extcon().

It appears to be caused by ulpi_read_id() masking the timeout on the first
test write. In the past dwc3 probe continued by calling dwc3_core_soft_reset()
followed by dwc3_get_extcon() which happend to return -EPROBE_DEFER.
On deferred probe ulpi_read_id() finally succeeded. Due to above mentioned
rearranging -EPROBE_DEFER is not returned and probe completes without phy.

As we now changed ulpi_read_id() to return -ETIMEDOUT in this case, we
need to handle the error by calling dwc3_core_soft_reset() and request
-EPROBE_DEFER. On deferred probe ulpi_read_id() is retried and succeeds.

Fixes: ef6a7bcfb01c ("usb: ulpi: Support device discovery via DT")
Cc: stable@vger.kernel.org

Signed-off-by: Ferry Toth <ftoth@exalondelft.nl>
---
 drivers/usb/dwc3/core.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

Comments

Andy Shevchenko Nov. 21, 2022, 8:37 a.m. UTC | #1 
On Sun, Nov 20, 2022 at 04:37:04PM +0100, Ferry Toth wrote:
> Since commit 0f0101719138 ("usb: dwc3: Don't switch OTG -> peripheral if extcon is present"),
> Dual Role support on Intel Merrifield platform broke due to rearranging
> the call to dwc3_get_extcon().
> 
> It appears to be caused by ulpi_read_id() masking the timeout on the first
> test write. In the past dwc3 probe continued by calling dwc3_core_soft_reset()
> followed by dwc3_get_extcon() which happend to return -EPROBE_DEFER.
> On deferred probe ulpi_read_id() finally succeeded. Due to above mentioned
> rearranging -EPROBE_DEFER is not returned and probe completes without phy.
> 
> As we now changed ulpi_read_id() to return -ETIMEDOUT in this case, we
> need to handle the error by calling dwc3_core_soft_reset() and request
> -EPROBE_DEFER. On deferred probe ulpi_read_id() is retried and succeeds.
> 
> Fixes: ef6a7bcfb01c ("usb: ulpi: Support device discovery via DT")
> Cc: stable@vger.kernel.org
> 
> Signed-off-by: Ferry Toth <ftoth@exalondelft.nl>

Same comments as per patch 1.

But before sending v5, let give a chance to others to review the code and other
aspects of the changes.
diff mbox series

Patch

diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
index 648f1c570021..2779f17bffaf 100644
--- a/drivers/usb/dwc3/core.c
+++ b/drivers/usb/dwc3/core.c
@@ -1106,8 +1106,13 @@  static int dwc3_core_init(struct dwc3 *dwc)
 
 	if (!dwc->ulpi_ready) {
 		ret = dwc3_core_ulpi_init(dwc);
-		if (ret)
+		if (ret) {
+			if (ret == -ETIMEDOUT) {
+				dwc3_core_soft_reset(dwc);
+				ret = -EPROBE_DEFER;
+			}
 			goto err0;
+		}
 		dwc->ulpi_ready = true;
 	}