linux-kernel - Re: Re: [RFC 8/9] PCI/pwrctl: add PCI power control core code

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Date: Fri, 2 Feb 2024 10:52:11 -0600
From: Bjorn Andersson <andersson@...nel.org>
To: Bartosz Golaszewski <brgl@...ev.pl>
Cc: Konrad Dybcio <konrad.dybcio@...aro.org>, 
	Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>, 
	Conor Dooley <conor+dt@...nel.org>, Marcel Holtmann <marcel@...tmann.org>, 
	Luiz Augusto von Dentz <luiz.dentz@...il.com>, Bjorn Helgaas <bhelgaas@...gle.com>, 
	Neil Armstrong <neil.armstrong@...aro.org>, Alex Elder <elder@...aro.org>, 
	Srini Kandagatla <srinivas.kandagatla@...aro.org>, Greg Kroah-Hartman <gregkh@...uxfoundation.org>, 
	Arnd Bergmann <arnd@...db.de>, Abel Vesa <abel.vesa@...aro.org>, 
	Manivannan Sadhasivam <mani@...nel.org>, Lukas Wunner <lukas@...ner.de>, linux-arm-msm@...r.kernel.org, 
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org, linux-bluetooth@...r.kernel.org, 
	linux-pci@...r.kernel.org, Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
Subject: Re: Re: [RFC 8/9] PCI/pwrctl: add PCI power control core code

On Fri, Feb 02, 2024 at 10:11:42AM +0100, Bartosz Golaszewski wrote:
> On Fri, Feb 2, 2024 at 4:53 AM Bjorn Andersson <andersson@...nel.org> wrote:
[..]
> > > +             break;
> > > +     }
> > > +
> > > +     return NOTIFY_DONE;
> > > +}
> > > +
> > > +int pci_pwrctl_device_enable(struct pci_pwrctl *pwrctl)
> >
> > This function doesn't really "enable the device", looking at the example
> > driver it's rather "device_enabled" than "device_enable"...
> >
> 
> I was also thinking about pci_pwrctl_device_ready() or
> pci_pwrctl_device_prepared().

I like both of these.

I guess the bigger question is how the flow would look like in the event
that we need to power-cycle the attached PCIe device, e.g. because
firmware has gotten into a really bad state.

Will we need an operation that removes the device first, and then cut
the power, or do we cut the power and then call unprepared()?

Regards,
Bjorn

> 
> Bart
> 
> [snip!]