linux-kernel - RE: [PATCH v4 0/3] Fix problems fetching TBT3 DROM from AMD USB4 routers

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Message-ID: <MN0PR12MB6101C93AC579DB2E23952D83E2B69@MN0PR12MB6101.namprd12.prod.outlook.com>
Date:   Mon, 6 Mar 2023 15:14:07 +0000
From:   "Limonciello, Mario" <Mario.Limonciello@....com>
To:     Mika Westerberg <mika.westerberg@...ux.intel.com>
CC:     "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
        "Mehta, Sanju" <Sanju.Mehta@....com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH v4 0/3] Fix problems fetching TBT3 DROM from AMD USB4
 routers

[Public]



> -----Original Message-----
> From: Mika Westerberg <mika.westerberg@...ux.intel.com>
> Sent: Monday, March 6, 2023 03:58
> To: Limonciello, Mario <Mario.Limonciello@....com>
> Cc: linux-usb@...r.kernel.org; Mehta, Sanju <Sanju.Mehta@....com>;
> linux-kernel@...r.kernel.org
> Subject: Re: [PATCH v4 0/3] Fix problems fetching TBT3 DROM from AMD
> USB4 routers
> 
> Hi Mario,
> 
> On Thu, Feb 23, 2023 at 03:07:40PM -0600, Mario Limonciello wrote:
> > TBT3 devices when connected to an AMD USB4 router occasionally fail to
> > properly respond to requests for the DROM via bit banging.
> >
> > Depending upon which part of the request failed will impact the severity.
> > A number of workarounds have been put in place to let the driver handle
> > the failed requests:
> >
> > commit e87491a9fd4e3 ("thunderbolt: Retry DROM reads for more failure
> scenarios")
> > commit a283de3ec646f ("thunderbolt: Do not resume routers if UID is not
> set")
> > commit 6915812bbd109 ("thunderbolt: Do not make DROM read success
> compulsory")
> > commit f022ff7bf377 ("thunderbolt: Retry DROM read once if parsing fails")
> >
> > Still even with these changes the failures do make it through. In comparing
> > other CM implementations utilized on AMD systems, they all access the
> > DROM directly from the NVM.
> >
> > To avoid triggering this issue, try to get the DROM directly from the NVM
> > in Linux as well when devices have an LC.
> >
> > v4:
> >  * Style fixups
> >  * Fixup for wrong path for USB4 devices
> >
> > Mario Limonciello (3):
> >   thunderbolt: Adjust how NVM reading works
> >   thunderbolt: use `tb_eeprom_get_drom_offset` to discover DROM offset
> >   thunderbolt: Refactor DROM reading
> 
> I split the device side into a separate function too, renamed root
> switch to host router (as that's the correct USB4 term), and fixed a
> couple style issues and applied to thunderbolt.git/next, thanks!
> 
> Please check that I did not mess up anything :)

They look good, thanks!

Would you consider to take 8d7f459107f74fbbdde3dd5b3874d2e748cb8a21 to
the RC though, or would prefer to let it bake in next?