Re: [PATCH v1] PCI: imx6: Set MSI enable bit of RC in resume

[Lucas Stach <l.stach@pengutronix.de>]

Am Freitag, dem 25.11.2022 um 02:07 +0000 schrieb Hongxing Zhu:
> Friendly ping.
> Anymore comments are very appreciated.
> 
> BTW, I had verified on i.MX7D/i.MX6QP platforms that MSI wouldn’t be functional
>  after resume without this patch.

Instead of playing whack-a-mole and restoring individual config setting
after resume, shouldn't we just do a pci_save_state() on suspend and
then restore the complete config by calling pci_restore_state() on
resume?

Regards,
Lucas

> 
> Best Regards
> Richard Zhu
> 
> > -----Original Message-----
> > From: Richard Zhu <hongxing.zhu@nxp.com>
> > Sent: 2022年11月1日 16:00
> > To: l.stach@pengutronix.de; bhelgaas@google.com;
> > lorenzo.pieralisi@arm.com
> > Cc: Hongxing Zhu <hongxing.zhu@nxp.com>; linux-pci@vger.kernel.org;
> > linux-arm-kernel@lists.infradead.org; linux-kernel@vger.kernel.org;
> > kernel@pengutronix.de; dl-linux-imx <linux-imx@nxp.com>
> > Subject: [PATCH v1] PCI: imx6: Set MSI enable bit of RC in resume
> > 
> > The MSI Enable bit controls delivery of MSI interrupts from components below
> > the Root Port. This bit might lost during the suspend, should be re-configured
> > during resume.
> > 
> > Encapsulate the MSI enable set into a standalone function, and invoke it in
> > both probe and resume.
> > 
> > Signed-off-by: Richard Zhu <hongxing.zhu@nxp.com>
> > ---
> >  drivers/pci/controller/dwc/pci-imx6.c | 24 +++++++++++++++++-------
> >  1 file changed, 17 insertions(+), 7 deletions(-)
> > 
> > diff --git a/drivers/pci/controller/dwc/pci-imx6.c
> > b/drivers/pci/controller/dwc/pci-imx6.c
> > index 2616585ca5f8..dba15546075f 100644
> > --- a/drivers/pci/controller/dwc/pci-imx6.c
> > +++ b/drivers/pci/controller/dwc/pci-imx6.c
> > @@ -1041,6 +1041,21 @@ static void imx6_pcie_pm_turnoff(struct
> > imx6_pcie *imx6_pcie)
> >  	usleep_range(1000, 10000);
> >  }
> > 
> > +static void pci_imx_set_msi_en(struct dw_pcie *pci) {
> > +	u8 offset;
> > +	u16 val;
> > +
> > +	if (pci_msi_enabled()) {
> > +		offset = dw_pcie_find_capability(pci, PCI_CAP_ID_MSI);
> > +		dw_pcie_dbi_ro_wr_en(pci);
> > +		val = dw_pcie_readw_dbi(pci, offset + PCI_MSI_FLAGS);
> > +		val |= PCI_MSI_FLAGS_ENABLE;
> > +		dw_pcie_writew_dbi(pci, offset + PCI_MSI_FLAGS, val);
> > +		dw_pcie_dbi_ro_wr_dis(pci);
> > +	}
> > +}
> > +
> >  static int imx6_pcie_suspend_noirq(struct device *dev)  {
> >  	struct imx6_pcie *imx6_pcie = dev_get_drvdata(dev); @@ -1073,6
> > +1088,7 @@ static int imx6_pcie_resume_noirq(struct device *dev)
> >  	if (imx6_pcie->link_is_up)
> >  		imx6_pcie_start_link(imx6_pcie->pci);
> > 
> > +	pci_imx_set_msi_en(imx6_pcie->pci);
> >  	return 0;
> >  }
> > 
> > @@ -1090,7 +1106,6 @@ static int imx6_pcie_probe(struct platform_device
> > *pdev)
> >  	struct resource *dbi_base;
> >  	struct device_node *node = dev->of_node;
> >  	int ret;
> > -	u16 val;
> > 
> >  	imx6_pcie = devm_kzalloc(dev, sizeof(*imx6_pcie), GFP_KERNEL);
> >  	if (!imx6_pcie)
> > @@ -1282,12 +1297,7 @@ static int imx6_pcie_probe(struct platform_device
> > *pdev)
> >  	if (ret < 0)
> >  		return ret;
> > 
> > -	if (pci_msi_enabled()) {
> > -		u8 offset = dw_pcie_find_capability(pci, PCI_CAP_ID_MSI);
> > -		val = dw_pcie_readw_dbi(pci, offset + PCI_MSI_FLAGS);
> > -		val |= PCI_MSI_FLAGS_ENABLE;
> > -		dw_pcie_writew_dbi(pci, offset + PCI_MSI_FLAGS, val);
> > -	}
> > +	pci_imx_set_msi_en(pci);
> > 
> >  	return 0;
> >  }
> > --
> > 2.25.1
>