linux-kernel - Re: [PATCH v4 2/2] usb: dwc3: core: defer probe on ulpi_read

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Date:   Mon, 21 Nov 2022 10:37:11 +0200
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Ferry Toth <ftoth@...londelft.nl>
Cc:     linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
        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>,
        stable@...r.kernel.org
Subject: Re: [PATCH v4 2/2] usb: dwc3: core: defer probe on ulpi_read_id
 timeout

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@...r.kernel.org
> 
> Signed-off-by: Ferry Toth <ftoth@...londelft.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.

-- 
With Best Regards,
Andy Shevchenko