linux-kernel - Re: [PATCH v4 4/4] PCI: tegra: Drop unused remove callback

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Message-ID: <nsldcdzdf7xazzm3dlb4jrjkehgt3hjlar7uc62twpkwocrer3@u5kirzyify4n>
Date: Sat, 10 May 2025 11:54:38 +0530
From: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
To: Aaron Kling <webgeek1234@...il.com>
Cc: Thomas Gleixner <tglx@...utronix.de>, 
	Lorenzo Pieralisi <lpieralisi@...nel.org>, Krzysztof Wilczyński <kw@...ux.com>, 
	Rob Herring <robh@...nel.org>, Bjorn Helgaas <bhelgaas@...gle.com>, 
	Thierry Reding <thierry.reding@...il.com>, Jonathan Hunter <jonathanh@...dia.com>, 
	"Rafael J. Wysocki" <rafael@...nel.org>, Daniel Lezcano <daniel.lezcano@...aro.org>, 
	linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org, linux-tegra@...r.kernel.org, 
	linux-pm@...r.kernel.org
Subject: Re: [PATCH v4 4/4] PCI: tegra: Drop unused remove callback

On Mon, May 05, 2025 at 11:59:27AM -0500, Aaron Kling wrote:
> On Mon, May 5, 2025 at 11:48 AM Manivannan Sadhasivam
> <manivannan.sadhasivam@...aro.org> wrote:
> >
> > On Mon, May 05, 2025 at 11:43:26AM -0500, Aaron Kling wrote:
> > > On Mon, May 5, 2025 at 11:32 AM Manivannan Sadhasivam
> > > <manivannan.sadhasivam@...aro.org> wrote:
> > > >
> > > > On Mon, May 05, 2025 at 09:59:01AM -0500, Aaron Kling via B4 Relay wrote:
> > > > > From: Aaron Kling <webgeek1234@...il.com>
> > > > >
> > > > > Debugfs cleanup is moved to a new shutdown callback to ensure the
> > > > > debugfs nodes are properly cleaned up on shutdown and reboot.
> > > > >
> > > >
> > > > Both are separate changes. You should remove the .remove() callback in the
> > > > previous patch itself and add .shutdown() callback in this patch.
> > > >
> > > > And the shutdown callback should quiesce the device by putting it in L2/L3 state
> > > > and turn off the supplies. It is not intended to perform resource cleanup.
> > >
> > > Then where would resource cleanup go?
> > >
> >
> > .remove(), but it is not useful here since the driver is not getting removed.
> 
> I may be misunderstanding how stuff works, but don't those resources
> still need cleaned up on shutdown/reboot even if the driver can't be
> unloaded? I recall seeing shutdown errors in the past when higher
> level debugfs nodes tried to clean themselves up, but bad drivers had
> left their nodes behind.
> 

Each callback has its own purpose. The cleanup is only performed by the
.remove() callback, but it will only get called when the driver gets removed.

> In any case, do you want me to just not add .shutdown() at all, or try
> to set the proper power state? Prior to the half-baked attempt to make
> this driver a loadable module several years ago, there was no such
> cleanup.
> 

As a first step, you can ignore .shutdown() callback and just remove the
.remove(). Shutdown callback implementation should follow the steps I mentioned
above, so it can be done later.

- Mani

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