linux-kernel - Re: [PATCH v1 1/1] phy: ti: tusb1210: Don't check for write errors when powering on

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Date:   Tue, 14 Jun 2022 17:49:22 +0200
From:   Hans de Goede <hdegoede@...hat.com>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc:     Vinod Koul <vkoul@...nel.org>,
        Stephan Gerhold <stephan@...hold.net>,
        linux-phy@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Kishon Vijay Abraham I <kishon@...com>,
        Ferry Toth <ftoth@...londelft.nl>
Subject: Re: [PATCH v1 1/1] phy: ti: tusb1210: Don't check for write errors
 when powering on

Hi,

On 6/14/22 15:01, Andy Shevchenko wrote:
> On Tue, Jun 14, 2022 at 01:23:21PM +0200, Hans de Goede wrote:
>> On 6/13/22 18:08, Andy Shevchenko wrote:
>>> On some platforms, like Intel Merrifield, the writing values during power on
>>> may timeout:
>>>
>>>    tusb1210 dwc3.0.auto.ulpi: error -110 writing val 0x41 to reg 0x80
>>>    phy phy-dwc3.0.auto.ulpi.0: phy poweron failed --> -110
>>>    dwc3 dwc3.0.auto: error -ETIMEDOUT: failed to initialize core
>>>    dwc3: probe of dwc3.0.auto failed with error -110
>>>
>>> which effectively fails the probe of the USB controller.
>>> Drop the check as it was before the culprit commit (see Fixes tag).
>>>
>>> Fixes: 09a3512681b3 ("phy: ti: tusb1210: Improve ulpi_read()/_write() error checking")
>>> Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
>>
>> Copy and pasting my reply about this in another thread to keep everyone up2date:
> 
> Thanks! My replies below.
> 
>> """
>> In my experience with using the phy for charger-type detection on some
>> x86 android tablets which don't have any other way to do charger detection,
>> these errors indicate a real communication issue for reading/writing
>> phy registers. At the same time this usually does not seem to be a big
>> problem since the phy seems to work fine with its power-on defaults.
>>
>> In case of Bay Trail these errors were related to 2 things:
>>
>> 1. Autosuspend of the phy-interface block in the dwc3, fixed by:
>>
>> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=d7c93a903f33ff35aa0e6b5a8032eb9755b00826
>>
>> But dwc3_pci_mrfld_properties[] already sets "snps,dis_u2_susphy_quirk",
>> so I guess it is not this.
>>
>> 2. There being no delay in tusb1210_power_on() between toggling the
>> reset IO and then trying to communicate with the phy, fixed in:
>>
>> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=df37c99815d9e0775e67276d70c93cbc25f31c70
>>
>> Maybe the:
>>
>> #define TUSB1210_RESET_TIME_MS				30
> 
> Actually it's 50.
> 
>> Added by that commit needs to be a bit bigger for the possibly
>> older phy revision used on the merifield boards?
>>
>> (note it is fine to just increase it a bit everywhere).
>> """
>>
>> IMHO it would be good to try and increase TUSB1210_RESET_TIME_MS (start with say 100
>> and then see if e.g. 50 also works). If increasing that does not work
> 
> No help
> 
> [   35.126397] tusb1210 dwc3.0.auto.ulpi: GPIO lookup for consumer reset
> [   35.126418] tusb1210 dwc3.0.auto.ulpi: using ACPI for GPIO lookup
> [   35.126455] tusb1210 dwc3.0.auto.ulpi: using lookup tables for GPIO lookup
> [   35.126465] tusb1210 dwc3.0.auto.ulpi: No GPIO consumer reset found
> [   35.126476] tusb1210 dwc3.0.auto.ulpi: GPIO lookup for consumer cs
> [   35.126485] tusb1210 dwc3.0.auto.ulpi: using ACPI for GPIO lookup
> [   35.126538] tusb1210 dwc3.0.auto.ulpi: using lookup tables for GPIO lookup
> [   35.126548] tusb1210 dwc3.0.auto.ulpi: No GPIO consumer cs found
> [   40.534107] tusb1210 dwc3.0.auto.ulpi: error -110 writing val 0x41 to reg 0x80
> 
> (I put 5000 ms there to be sure)
> 
>> I'm fine with going with this workaround patch to fix things.

Ok, so I guess we should just apply this workaround patch to make
the error non fatal. Still would be good to dig a little deeper one
of these days and see what is going on here...

Regards,

Hans