linux-kernel - RE: [PATCH] x86/gpu: add JSL stolen memory support

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Date:   Thu, 3 Dec 2020 16:09:50 +0000
From:   "Surendrakumar Upadhyay, TejaskumarX" 
        <tejaskumarx.surendrakumar.upadhyay@...el.com>
To:     Bjorn Helgaas <helgaas@...nel.org>,
        Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>
CC:     Jesse Barnes <jsbarnes@...gle.com>,
        Daniel Vetter <daniel@...ll.ch>,
        Linux PCI <linux-pci@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        X86 ML <x86@...nel.org>, Borislav Petkov <bp@...en8.de>,
        "De Marchi, Lucas" <lucas.demarchi@...el.com>,
        "Roper, Matthew D" <matthew.d.roper@...el.com>,
        "Pandey, Hariom" <hariom.pandey@...el.com>,
        Jani Nikula <jani.nikula@...ux.intel.com>,
        "Vivi, Rodrigo" <rodrigo.vivi@...el.com>,
        David Airlie <airlied@...ux.ie>
Subject: RE: [PATCH] x86/gpu: add JSL stolen memory support

Okay then I will wait for someone to respond with "Reviewed-by". So this can be merged.

Thanks,
Tejas

> -----Original Message-----
> From: Bjorn Helgaas <helgaas@...nel.org>
> Sent: 03 December 2020 20:55
> To: Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>
> Cc: Surendrakumar Upadhyay, TejaskumarX
> <tejaskumarx.surendrakumar.upadhyay@...el.com>; Jesse Barnes
> <jsbarnes@...gle.com>; Daniel Vetter <daniel@...ll.ch>; Linux PCI <linux-
> pci@...r.kernel.org>; Linux Kernel Mailing List <linux-
> kernel@...r.kernel.org>; X86 ML <x86@...nel.org>; Borislav Petkov
> <bp@...en8.de>; De Marchi, Lucas <lucas.demarchi@...el.com>; Roper,
> Matthew D <matthew.d.roper@...el.com>; Pandey, Hariom
> <hariom.pandey@...el.com>; Jani Nikula <jani.nikula@...ux.intel.com>; Vivi,
> Rodrigo <rodrigo.vivi@...el.com>; David Airlie <airlied@...ux.ie>
> Subject: Re: [PATCH] x86/gpu: add JSL stolen memory support
> 
> On Thu, Dec 03, 2020 at 10:46:29AM +0200, Joonas Lahtinen wrote:
> > Quoting Bjorn Helgaas (2020-12-02 22:22:53)
> > > On Wed, Dec 02, 2020 at 05:21:58AM +0000, Surendrakumar Upadhyay,
> TejaskumarX wrote:
> > > > Yes it fails all the tests which are allocating from this stolen
> > > > memory bunch. For example IGT tests like "
> > > > igt@..._frontbuffer_tracking@-[fbc|fbcpsr].* |
> > > > igt@..._fbcon_fbt@....* " are failing as they totally depend to
> > > > work on stolen memory.
> >
> > That's just because we have de-duped the stolen memory detection code.
> > If it's not detected at the early quirks, it's not detected by the
> > driver at all.
> >
> > So if the patch is not merged to early quirks, we'd have to refactor
> > the code to add alternative detection path to i915. Before that is
> > done, the failures are expected.
> >
> > > I'm sure that means something to graphics developers, but I have no
> > > idea!  Do you have URLs for the test case source, outputs, dmesg
> > > log, lspci info, bug reports, etc?
> >
> > The thing is, the bug reports for stuff like this would only start to
> > flow after Jasperlake systems are shipping widely and the less common
> > OEMs start integrating it to into strangely behaving BIOSes. Or that
> > is the assumption.
> >
> > If it's fine to merge this through i915 for now with an Acked-by, like
> > the previous patches, that'd be great. We can start a discussion on if
> > the new platforms are affected anymore. But I'd rather not drop it
> > before we have that understanding, as the previous problems have
> > included boot time memory corruption.
> >
> > Would that work?
> 
> Like I said, I'm not objecting if somebody else wants to apply this.
> 
> I'm just pointing out that there's a little bit of voodoo here because it's not
> clear what makes a BIOS strangely behaving or what causes boot-time
> memory corruption, and that means we don't really have any hope of
> resolving this stream of quirk updates.
> 
> Bjorn