* Re: [PATCH] nvme/pci: default to simple suspend
[not found] ` <20220411135850.GA42637@thinkpad>
@ 2022-04-23 5:49 ` Christoph Hellwig
0 siblings, 0 replies; only message in thread
From: Christoph Hellwig @ 2022-04-23 5:49 UTC (permalink / raw)
To: Manivannan Sadhasivam
Cc: hch, linux-nvme, sagi, Rafael Wysocki, Vidya Sagar, kbusch,
linux-pci
On Mon, Apr 11, 2022 at 07:28:50PM +0530, Manivannan Sadhasivam wrote:
> PCI core only accepts the quirks for the host devices that could be passed onto
> the PCI device drivers like this one. In this case, this is not a quirk but
> actually an aggressive power saving feature (atleast on the Qcom platforms).
> Moreover, adding a flag to the PCI bus will make it applicable to all the
> child devices of the RC/bridge and that would be wrong.
As you correctly state it is not a device quirk. It describes the
power management applied by the platform. So we do need to communicate
it through the core PM and/or PCI code. Please work with the relevant
maintainers.
> In our case, the same power saving feature is not applicable to all PCI devices
> like WLAN for an example.
This doesn't make sense. Your plaform can't know what device is connected
to a given root port / slot. So you might have different policies per
slot, but that has nothing to do with the Linux drivers for given devices.
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