linux-kernel - [PATCH v2 1/3] PCI: Add a flag to notify PCI drivers about powerdown during suspend

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Date:   Wed, 18 May 2022 18:49:11 +0530
From:   Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
To:     bhelgaas@...gle.com, lorenzo.pieralisi@....com, kbusch@...nel.org,
        hch@....de
Cc:     linux-nvme@...ts.infradead.org, linux-pci@...r.kernel.org,
        linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
        svarbanov@...sol.com, bjorn.andersson@...aro.org, axboe@...com,
        quic_vbadigan@...cinc.com, quic_krichai@...cinc.com,
        quic_nitirawa@...cinc.com, vidyas@...dia.com, sagi@...mberg.me,
        linux-pm@...r.kernel.org, rafael@...nel.org,
        Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
Subject: [PATCH v2 1/3] PCI: Add a flag to notify PCI drivers about powerdown during suspend

On some systems like Chromebooks based on Qcom SC7280, the PCIe RC
driver or a hardware entity like RPMh may powerdown all PCIe devices
during system suspend for aggressive powersaving. In that case, the
PCI host controller drivers need to notify the PCI device drivers that
the power will be taken off during system suspend so that the drivers
can prepare the devices accordingly.

One prime example is the PCI NVMe driver. This flag can be used by the
driver to shutdown the NVMe device during suspend and recover it during
resume.

Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
---

Changes in v2:

* Changed the comment for the flag to mention the usecase.
* Reworded the commit message to convey how the poweroff happens

 include/linux/pci.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/include/linux/pci.h b/include/linux/pci.h
index 60adf42460ab..3e3a1c4f4559 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -578,6 +578,8 @@ struct pci_host_bridge {
 	unsigned int	preserve_config:1;	/* Preserve FW resource setup */
 	unsigned int	size_windows:1;		/* Enable root bus sizing */
 	unsigned int	msi_domain:1;		/* Bridge wants MSI domain */
+	unsigned int	suspend_poweroff:1;	/* Some platforms like Qcom SC7280 may poweroff
+						   devices during system suspend for power saving */
 
 	/* Resource alignment requirements */
 	resource_size_t (*align_resource)(struct pci_dev *dev,
-- 
2.25.1