From: Mika Westerberg <mika.westerberg@linux.intel.com>
To: Lukas Wunner <lukas@wunner.de>
Cc: linux-kernel@vger.kernel.org,
Michael Jamet <michael.jamet@intel.com>,
Yehezkel Bernat <YehezkelShB@gmail.com>,
Andreas Noever <andreas.noever@gmail.com>,
Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Subject: Re: [PATCH v2 12/28] thunderbolt: Add functions for allocating and releasing hop IDs
Date: Tue, 12 Feb 2019 14:51:25 +0200 [thread overview]
Message-ID: <20190212125125.GG7875@lahna.fi.intel.com> (raw)
In-Reply-To: <20190212124333.hgrnm6owtuqzp4iu@wunner.de>
On Tue, Feb 12, 2019 at 01:43:33PM +0100, Lukas Wunner wrote:
> On Mon, Feb 11, 2019 at 10:30:43AM +0200, Mika Westerberg wrote:
> > On Sun, Feb 10, 2019 at 01:13:53PM +0100, Lukas Wunner wrote:
> > > If there are two Macs at the ends of the daisy-chain with Thunderbolt
> > > devices in-between, the other Mac may already have established tunnels
> > > to some of the devices and therefore has occupied hop entries in the
> > > devices' path config space. How do you ensure that you don't allocate
> > > the same entries and overwrite the other Mac's hop entries, thereby
> > > breaking its tunnels?
> >
> > If the other Mac has enumerated the device (set the upstream port,
> > route, depth) then the other Mac cannot access the device. You get an
> > error (we deal with that in the later patch in the series when we
> > identify XDomain connections). The Hop ID allocation is only relevant in
> > a single domain. Crossing one needs to have protocol such as we have in
> > case of ThunderboltIP to negotiate Hop IDs used in the link between two
> > domains.
>
> Understood now, thanks. (Well, in part at least.)
>
> It looks like there's a race condition currently in tb_switch_configure()
> wherein two machines on the daisy chain may write the config simultaneously
> and overwrite each other's changes. Isn't there some kind of synchonization
> mechanism available to prevent such an outcome?
AFAICT that's expected. The host that first enumerated the device wins.
next prev parent reply other threads:[~2019-02-12 12:51 UTC|newest]
Thread overview: 57+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-06 13:17 [PATCH v2 00/28] thunderbolt: Software connection manager improvements Mika Westerberg
2019-02-06 13:17 ` [PATCH v2 01/28] net: thunderbolt: Unregister ThunderboltIP protocol handler when suspending Mika Westerberg
2019-02-06 13:17 ` [PATCH v2 02/28] thunderbolt: Do not allocate switch if depth is greater than 6 Mika Westerberg
2019-02-06 13:17 ` [PATCH v2 03/28] thunderbolt: Enable TMU access when accessing port space on legacy devices Mika Westerberg
2019-02-06 13:17 ` [PATCH v2 04/28] thunderbolt: Add dummy read after port capability list walk on Light Ridge Mika Westerberg
2019-02-06 13:17 ` [PATCH v2 05/28] thunderbolt: Move LC specific functionality into a separate file Mika Westerberg
2019-02-06 13:17 ` [PATCH v2 06/28] thunderbolt: Configure lanes when switch is initialized Mika Westerberg
2019-02-06 13:17 ` [PATCH v2 07/28] thunderbolt: Set sleep bit when suspending switch Mika Westerberg
2019-02-06 13:17 ` [PATCH v2 08/28] thunderbolt: Properly disable path Mika Westerberg
2019-02-06 13:17 ` [PATCH v2 09/28] thunderbolt: Cache adapter specific capability offset into struct port Mika Westerberg
2019-02-06 13:17 ` [PATCH v2 10/28] thunderbolt: Rename tunnel_pci to tunnel Mika Westerberg
2019-02-06 13:17 ` [PATCH v2 11/28] thunderbolt: Generalize tunnel creation functionality Mika Westerberg
2019-02-06 13:17 ` [PATCH v2 12/28] thunderbolt: Add functions for allocating and releasing hop IDs Mika Westerberg
2019-02-10 12:13 ` Lukas Wunner
2019-02-11 8:30 ` Mika Westerberg
2019-02-12 12:43 ` Lukas Wunner
2019-02-12 12:51 ` Mika Westerberg [this message]
2019-02-12 12:59 ` Lukas Wunner
2019-02-12 13:02 ` Mika Westerberg
2019-02-06 13:17 ` [PATCH v2 13/28] thunderbolt: Add helper function to iterate from one port to another Mika Westerberg
2019-02-07 14:33 ` Andy Shevchenko
2019-02-11 6:16 ` Lukas Wunner
2019-02-11 9:54 ` Mika Westerberg
2019-02-12 13:55 ` Lukas Wunner
2019-02-12 19:03 ` Mika Westerberg
2019-02-06 13:17 ` [PATCH v2 14/28] thunderbolt: Extend tunnel creation to more than 2 adjacent switches Mika Westerberg
2019-02-10 15:33 ` Lukas Wunner
2019-02-11 8:45 ` Mika Westerberg
2019-02-12 12:54 ` Lukas Wunner
2019-02-06 13:17 ` [PATCH v2 15/28] thunderbolt: Deactivate all paths before restarting them Mika Westerberg
2019-02-11 6:35 ` Lukas Wunner
2019-02-11 8:52 ` Mika Westerberg
2019-02-06 13:17 ` [PATCH v2 16/28] thunderbolt: Discover preboot PCIe paths the boot firmware established Mika Westerberg
2019-02-12 17:49 ` Lukas Wunner
2019-02-12 18:34 ` Mika Westerberg
2019-02-12 19:42 ` Lukas Wunner
2019-02-13 8:30 ` Mika Westerberg
2019-02-06 13:17 ` [PATCH v2 17/28] thunderbolt: Add support for full PCIe daisy chains Mika Westerberg
2019-03-24 11:31 ` Lukas Wunner
2019-03-25 9:57 ` Mika Westerberg
2019-03-25 11:16 ` Lukas Wunner
2019-03-25 11:22 ` Mika Westerberg
2019-02-06 13:17 ` [PATCH v2 18/28] thunderbolt: Scan only valid NULL adapter ports in hotplug Mika Westerberg
2019-02-12 14:04 ` Lukas Wunner
2019-02-12 18:46 ` Mika Westerberg
2019-02-06 13:17 ` [PATCH v2 19/28] thunderbolt: Generalize port finding routines to support all port types Mika Westerberg
2019-02-06 13:17 ` [PATCH v2 20/28] thunderbolt: Rework NFC credits handling Mika Westerberg
2019-02-06 13:17 ` [PATCH v2 21/28] thunderbolt: Add support for Display Port tunnels Mika Westerberg
2019-02-07 14:28 ` Andy Shevchenko
2019-02-06 13:17 ` [PATCH v2 22/28] thunderbolt: Run tb_xdp_handle_request() in system workqueue Mika Westerberg
2019-02-06 13:17 ` [PATCH v2 23/28] thunderbolt: Add XDomain UUID exchange support Mika Westerberg
2019-02-06 13:17 ` [PATCH v2 24/28] thunderbolt: Add support for DMA tunnels Mika Westerberg
2019-02-06 13:17 ` [PATCH v2 25/28] thunderbolt: Make tb_switch_alloc() return ERR_PTR() Mika Westerberg
2019-02-06 13:17 ` [PATCH v2 26/28] thunderbolt: Add support for XDomain connections Mika Westerberg
2019-02-06 13:17 ` [PATCH v2 27/28] thunderbolt: Make rest of the logging to happen at debug level Mika Westerberg
2019-02-06 13:17 ` [PATCH v2 28/28] thunderbolt: Start firmware on Titan Ridge Apple systems Mika Westerberg
2019-02-07 14:22 ` [PATCH v2 00/28] thunderbolt: Software connection manager improvements Andy Shevchenko
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