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SubjectRe: [PATCH V4 4/6] PCI: tegra: Continue unconfig sequence even if parts fail
On Tue, Dec 01, 2020 at 03:24:24PM +0100, Thierry Reding wrote:
> On Mon, Nov 30, 2020 at 12:10:07PM +0000, Lorenzo Pieralisi wrote:
> > On Mon, Nov 09, 2020 at 10:49:35PM +0530, Vidya Sagar wrote:
> > > Currently the driver checks for error value of different APIs during the
> > > uninitialization sequence. It just returns from there if there is any error
> > > observed for one of those calls. Comparatively it is better to continue the
> > > uninitialization sequence irrespective of whether some of them are
> > > returning error. That way, it is more closer to complete uninitialization.
> >
> > Hi Vidya, Thierry,
> >
> > I can apply this series (dropping patches as suggested by Thierry),
> > before though I wanted to ask you if this patch is really an
> > improvement, it is hard to understand why skipping some error
> > codes is OK for device correct operations to continue, maybe it
> > is worth describing why some of those failures aren't really
> > fatal.
> >
> > Please let me know, thanks.
>
> As explained in the commit message, the idea is to continue tearing
> down even if things fail somewhere in the middle, because that ensures
> that the hardware gets as close to an "uninitialized" state as possible.
> If for example the first reset assert were to fail, then none of the
> PHYs get disabled, the regulator stays on and the clocks stays on, all
> of which can continue draining power after the controller has already
> been torn down.

Understood. By reading the code it looked weird that eg a reset failure
was tolerable - I thought an error would be fatal (I don't know what are
the consequences for instance on a subsequent resume) but it looks like
it actually is not, that's the only point I raised.

> So yes, I think this is an improvement. It's unclear to me what you're
> asking for, though. Would you rather have a comment somewhere near the
> tegra_pcie_unconfig_controller() function that states the same thing as
> the commit message?

It could be useful but it is up to you, I will merge the series as-is
or I can add it myself, as you wish.

Thanks,
Lorenzo

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