From: Mika Westerberg <mika.westerberg@linux.intel.com>
To: Lukas Wunner <lukas@wunner.de>
Cc: linux-usb@vger.kernel.org,
Michael Jamet <michael.jamet@intel.com>,
Yehezkel Bernat <YehezkelShB@gmail.com>,
Andreas Noever <andreas.noever@gmail.com>,
Kai-Heng Feng <kai.heng.feng@canonical.com>
Subject: Re: [PATCH] thunderbolt: Retry DROM read once if parsing fails
Date: Mon, 7 Sep 2020 15:02:56 +0300 [thread overview]
Message-ID: <20200907120256.GL2495@lahna.fi.intel.com> (raw)
In-Reply-To: <20200907112151.GA22115@wunner.de>
On Mon, Sep 07, 2020 at 01:21:51PM +0200, Lukas Wunner wrote:
> On Mon, Sep 07, 2020 at 02:03:40PM +0300, Mika Westerberg wrote:
> > Kai-Heng reported that sometimes DROM parsing of ASUS PA27AC Thunderbolt 3
> > monitor fails. This makes the driver to fail to add the device so only
> > DisplayPort tunneling is functional.
>
> Maybe the DROM is contained in an external EEPROM attached via slow
> SPI or i2c and cannot be read in time before a response on the control
> channel is due? Does it help to always delay 100 ms before performing
> the DROM read with this display? Perhaps a quirk specific for this
> display is more appropriate than a change which affects all devices?
> Because this way of working around problems is difficult to maintain
> long term.
It helps to always wait the 100ms IIRC but I'm not sure we want to do
that for every device. Also I'm not a fan of maintaining a list of
quirks if we have the possibility to have more "general" solution to the
issue (like what we do here, retry once).
next prev parent reply other threads:[~2020-09-07 12:04 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-07 11:03 [PATCH] thunderbolt: Retry DROM read once if parsing fails Mika Westerberg
2020-09-07 11:21 ` Lukas Wunner
2020-09-07 12:02 ` Mika Westerberg [this message]
2020-09-09 11:06 ` Mika Westerberg
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