linux-kernel - [PATCH v5 1/2] usb: ulpi: defer ulpi_register on ulpi_read

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Message-Id: <20221205201527.13525-2-ftoth@exalondelft.nl>
Date:   Mon,  5 Dec 2022 21:15:26 +0100
From:   Ferry Toth <ftoth@...londelft.nl>
To:     linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Thinh Nguyen <Thinh.Nguyen@...opsys.com>,
        Sean Anderson <sean.anderson@...o.com>,
        Liu Shixin <liushixin2@...wei.com>,
        Ferry Toth <fntoth@...il.com>,
        Andrey Smirnov <andrew.smirnov@...il.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Ferry Toth <ftoth@...londelft.nl>, stable@...r.kernel.org
Subject: [PATCH v5 1/2] usb: ulpi: defer ulpi_register on ulpi_read_id timeout

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() on the first test write failing
with -ETIMEDOUT. Currently ulpi_read_id() expects to discover the phy via
DT when the test write fails and returns 0 in that case, even if DT does not
provide the phy. As a result usb probe completes without phy.

Make ulpi_read_id() return -ETIMEDOUT to its user if the first test write
fails. The user should then handle it appropriately. A follow up patch
will make dwc3_core_init() set -EPROBE_DEFER in this case and bail out.

Fixes: ef6a7bcfb01c ("usb: ulpi: Support device discovery via DT")
Cc: stable@...r.kernel.org
Signed-off-by: Ferry Toth <ftoth@...londelft.nl>
---
 drivers/usb/common/ulpi.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/usb/common/ulpi.c b/drivers/usb/common/ulpi.c
index d7c8461976ce..60e8174686a1 100644
--- a/drivers/usb/common/ulpi.c
+++ b/drivers/usb/common/ulpi.c
@@ -207,7 +207,7 @@ static int ulpi_read_id(struct ulpi *ulpi)
 	/* Test the interface */
 	ret = ulpi_write(ulpi, ULPI_SCRATCH, 0xaa);
 	if (ret < 0)
-		goto err;
+		return ret;

 	ret = ulpi_read(ulpi, ULPI_SCRATCH);
 	if (ret < 0)
-- 
2.37.2