linux-kernel - Re: [PATCH v2 3/3] PCI: dwc: Check for the device presence during suspend and resume

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <pzpyipassbzzsffys5mexxxip7oubwq37a564skb5udkfh363b@3sbkrz7atj3s>
Date: Thu, 13 Nov 2025 22:26:29 +0530
From: Manivannan Sadhasivam <mani@...nel.org>
To: Frank Li <Frank.li@....com>
Cc: Manivannan Sadhasivam <manivannan.sadhasivam@....qualcomm.com>, 
	lpieralisi@...nel.org, kwilczynski@...nel.org, bhelgaas@...gle.com, will@...nel.org, 
	linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org, robh@...nel.org, 
	linux-arm-msm@...r.kernel.org, zhangsenchuan@...incomputing.com, vincent.guittot@...aro.org
Subject: Re: [PATCH v2 3/3] PCI: dwc: Check for the device presence during
 suspend and resume

On Mon, Nov 10, 2025 at 11:26:38AM -0500, Frank Li wrote:
> On Fri, Nov 07, 2025 at 10:13:19AM +0530, Manivannan Sadhasivam wrote:
> > If there is no device available under the Root Ports, there is no point in
> > sending PME_Turn_Off and waiting for L2/L3 transition during suspend, it
> > will result in a timeout. Hence, skip those steps if no device is available
> > during suspend.
> >
> > During resume, do not wait for the link up if there was no device connected
> > before suspend. It is very unlikely that a device will get connected while
> > the host system was suspended.
> >
> > Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@....qualcomm.com>
> > ---
> >  drivers/pci/controller/dwc/pcie-designware-host.c | 13 +++++++++++++
> >  1 file changed, 13 insertions(+)
> >
> > diff --git a/drivers/pci/controller/dwc/pcie-designware-host.c b/drivers/pci/controller/dwc/pcie-designware-host.c
> > index 20c9333bcb1c..5a39e7139ec9 100644
> > --- a/drivers/pci/controller/dwc/pcie-designware-host.c
> > +++ b/drivers/pci/controller/dwc/pcie-designware-host.c
> > @@ -20,6 +20,7 @@
> >  #include <linux/platform_device.h>
> >
> >  #include "../../pci.h"
> > +#include "../pci-host-common.h"
> >  #include "pcie-designware.h"
> >
> >  static struct pci_ops dw_pcie_ops;
> > @@ -1129,6 +1130,9 @@ int dw_pcie_suspend_noirq(struct dw_pcie *pci)
> >  	u32 val;
> >  	int ret;
> >
> > +	if (!pci_root_ports_have_device(pci->pp.bridge->bus))
> > +		goto stop_link;
> > +
> >  	/*
> >  	 * If L1SS is supported, then do not put the link into L2 as some
> >  	 * devices such as NVMe expect low resume latency.
> > @@ -1162,6 +1166,7 @@ int dw_pcie_suspend_noirq(struct dw_pcie *pci)
> >  	 */
> >  	udelay(1);
> 
> I think move pme_turn_off() to helper funciton will make code look better
> 

What about the L2 entry timeout?

> 	if (pci_root_ports_have_device()) {
> 		ret = dwc_pme_turn_off();
> 		if (ret)
> 			return ret;
> 	};
> 
> 
> >
> > +stop_link:
> >  	dw_pcie_stop_link(pci);
> >  	if (pci->pp.ops->deinit)
> >  		pci->pp.ops->deinit(&pci->pp);
> > @@ -1195,6 +1200,14 @@ int dw_pcie_resume_noirq(struct dw_pcie *pci)
> >  	if (ret)
> >  		return ret;
> >
> > +	/*
> > +	 * If there was no device before suspend, skip waiting for link up as
> > +	 * it is bound to fail. It is very unlikely that a device will get
> > +	 * connected *during* suspend.
> 
> I think it should use certern term. the a device will not get linkup during
> suspend, if this happen, it is a new hotjoin device after system resume.
> 

Sure.

- Mani

-- 
மணிவண்ணன் சதாசிவம்