linux-kernel - Re: [PATCH v12 2/3] PCI: dwc: Implement general suspend/resume functionality for L2/L3 transitions

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Date: Thu, 1 Feb 2024 12:08:23 -0500
From: Frank Li <Frank.li@....com>
To: Bjorn Helgaas <helgaas@...nel.org>
Cc: bhelgaas@...gle.com, devicetree@...r.kernel.org,
	gustavo.pimentel@...opsys.com, imx@...ts.linux.dev, kw@...ux.com,
	leoyang.li@....com, linux-arm-kernel@...ts.infradead.org,
	linux-imx@....com, linux-kernel@...r.kernel.org,
	linux-pci@...r.kernel.org, lorenzo.pieralisi@....com,
	lpieralisi@...nel.org, mani@...nel.org,
	manivannan.sadhasivam@...aro.org, minghuan.lian@....com,
	mingkai.hu@....com, robh+dt@...nel.org, roy.zang@....com,
	shawnguo@...nel.org, zhiqiang.hou@....com
Subject: Re: [PATCH v12 2/3] PCI: dwc: Implement general suspend/resume
 functionality for L2/L3 transitions

On Thu, Feb 01, 2024 at 10:50:25AM -0600, Bjorn Helgaas wrote:
> On Mon, Aug 21, 2023 at 02:48:14PM -0400, Frank Li wrote:
> > Introduce helper function dw_pcie_get_ltssm() to retrieve SMLH_LTSS_STATE.
> > ...
> 
> > diff --git a/drivers/pci/controller/dwc/pcie-designware.h b/drivers/pci/controller/dwc/pcie-designware.h
> > index 615660640801..91d13f9b21b1 100644
> > --- a/drivers/pci/controller/dwc/pcie-designware.h
> > +++ b/drivers/pci/controller/dwc/pcie-designware.h
> 
> > @@ -364,6 +375,7 @@ struct dw_pcie_ops {
> >  	void    (*write_dbi2)(struct dw_pcie *pcie, void __iomem *base, u32 reg,
> >  			      size_t size, u32 val);
> >  	int	(*link_up)(struct dw_pcie *pcie);
> > +	enum dw_pcie_ltssm (*get_ltssm)(struct dw_pcie *pcie);
> 
> This has already been applied as
> https://git.kernel.org/linus/4774faf854f5 ("PCI: dwc: Implement
> generic suspend/resume functionality"), but this .get_ltssm() pointer
> doesn't seem to be used anywhere.  Should we remove it until we need
> it?

Could you place hold on for a while? I am working on imx PCIe. One old
imx6 may need it!

If not, I will submit patch to clean it. My new patches depend on

https://lore.kernel.org/imx/ZbJ+tFPn3aOYHCwf@lizhi-Precision-Tower-5810/T/#t

All already reviewed, could you please pick up these, so I can continue
my futher work.

Another
https://lore.kernel.org/imx/20240201-pme_msg-v2-0-6767052fe6a4@nxp.com/T/#t
was under review.

After these, suspend/resume will become simple and common for all dwc
platform.

Frank.

> 
> > +static inline enum dw_pcie_ltssm dw_pcie_get_ltssm(struct dw_pcie *pci)
> > +{
> > +	u32 val;
> > +
> > +	if (pci->ops && pci->ops->get_ltssm)
> > +		return pci->ops->get_ltssm(pci);
> > +
> > +	val = dw_pcie_readl_dbi(pci, PCIE_PORT_DEBUG0);
> > +
> > +	return (enum dw_pcie_ltssm)FIELD_GET(PORT_LOGIC_LTSSM_STATE_MASK, val);
> > +}