Re: [PATCH v5 06/11] drm/radeon: Use RMW accessors for changing LNKCTL

[Bjorn Helgaas]

On Fri, Aug 18, 2023 at 04:12:57PM +0000, Deucher, Alexander wrote:
> > -----Original Message-----
> > From: Ilpo Järvinen <ilpo.jarvinen@xxxxxxxxxxxxxxx>
> > Sent: Monday, July 17, 2023 8:05 AM
> > To: linux-pci@xxxxxxxxxxxxxxx; Bjorn Helgaas <bhelgaas@xxxxxxxxxx>; Lorenzo
> > Pieralisi <lorenzo.pieralisi@xxxxxxx>; Rob Herring <robh@xxxxxxxxxx>;
> > Krzysztof Wilczyński <kw@xxxxxxxxx>; Emmanuel Grumbach
> > <emmanuel.grumbach@xxxxxxxxx>; Rafael J . Wysocki <rafael@xxxxxxxxxx>;
> > Heiner Kallweit <hkallweit1@xxxxxxxxx>; Lukas Wunner <lukas@xxxxxxxxx>;
> > Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>; Deucher, Alexander
> > <Alexander.Deucher@xxxxxxx>; Koenig, Christian
> > <Christian.Koenig@xxxxxxx>; Pan, Xinhui <Xinhui.Pan@xxxxxxx>; David
> > Airlie <airlied@xxxxxxxxx>; Daniel Vetter <daniel@xxxxxxxx>; amd-
> > gfx@xxxxxxxxxxxxxxxxxxxxx; dri-devel@xxxxxxxxxxxxxxxxxxxxx; linux-
> > kernel@xxxxxxxxxxxxxxx
> > Cc: Dean Luick <dean.luick@xxxxxxxxxxxxxxxxxxxx>; Jonas Dreßler
> > <verdre@xxxxxxx>; Ilpo Järvinen <ilpo.jarvinen@xxxxxxxxxxxxxxx>;
> > stable@xxxxxxxxxxxxxxx
> > Subject: [PATCH v5 06/11] drm/radeon: Use RMW accessors for changing
> > LNKCTL
> >
> > Don't assume that only the driver would be accessing LNKCTL. ASPM policy
> > changes can trigger write to LNKCTL outside of driver's control.
> > And in the case of upstream bridge, the driver does not even own the device
> > it's changing the registers for.
> >
> > Use RMW capability accessors which do proper locking to avoid losing
> > concurrent updates to the register value.
> >
> > Fixes: 8a7cd27679d0 ("drm/radeon/cik: add support for pcie gen1/2/3
> > switching")
> > Fixes: b9d305dfb66c ("drm/radeon: implement pcie gen2/3 support for SI")
> > Suggested-by: Lukas Wunner <lukas@xxxxxxxxx>
> > Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@xxxxxxxxxxxxxxx>
> > Cc: stable@xxxxxxxxxxxxxxx
> 
> For this and the amdgpu patch:
> Acked-by: Alex Deucher <alexander.deucher@xxxxxxx>
> I'm not sure if this is stable material however.  Is there some issue today?

Added your ack, thanks!  I dropped the stable tag on the whole series.

Bjorn