linux-kernel - RE: [v2] PCI: imx: make msi work without pcieportbus

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Date:   Thu, 13 Dec 2018 08:23:52 +0000
From:   Richard Zhu <hongxing.zhu@....com>
To:     Baruch Siach <baruch@...s.co.il>
CC:     "bhelgaas@...gle.com" <bhelgaas@...gle.com>,
        "lorenzo.pieralisi@....com" <lorenzo.pieralisi@....com>,
        "l.stach@...gutronix.de" <l.stach@...gutronix.de>,
        "andrew.smirnov@...il.com" <andrew.smirnov@...il.com>,
        "linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>
Subject: RE: [v2] PCI: imx: make msi work without pcieportbus



> -----Original Message-----
> From: Baruch Siach [mailto:baruch@...s.co.il]
> Sent: 2018年12月13日 16:13
> To: Richard Zhu <hongxing.zhu@....com>
> Cc: bhelgaas@...gle.com; lorenzo.pieralisi@....com;
> l.stach@...gutronix.de; andrew.smirnov@...il.com;
> linux-pci@...r.kernel.org; linux-kernel@...r.kernel.org;
> linux-arm-kernel@...ts.infradead.org
> Subject: Re: [v2] PCI: imx: make msi work without pcieportbus
> 
> Hi Richard,
> 
> One more comment that occurred to me only now.
> 
> Richard Zhu writes:
> > MSI_EN of iMX PCIe RC would be asserted when PCIEPORTBUS driver is
> > selected.
> > Thus, the MSI works fine on iMX PCIe before.
> > Assert it unconditionally when MSI is supported.
> > Otherwise, the MSI wouldn't be triggered although the EP is present
> > and the MSIs are assigned.
> >
> > Signed-off-by: Richard Zhu <hongxing.zhu@....com>
> > ---
> >  drivers/pci/controller/dwc/pci-imx6.c | 7 +++++++
> >  1 file changed, 7 insertions(+)
> >
> > diff --git a/drivers/pci/controller/dwc/pci-imx6.c
> > b/drivers/pci/controller/dwc/pci-imx6.c
> > index 26087b3..d3e4296 100644
> > --- a/drivers/pci/controller/dwc/pci-imx6.c
> > +++ b/drivers/pci/controller/dwc/pci-imx6.c
> > @@ -74,6 +74,7 @@ struct imx6_pcie {
> >  #define PHY_PLL_LOCK_WAIT_USLEEP_MAX	200
> >
> >  /* PCIe Root Complex registers (memory-mapped) */
> > +#define PCI_MSI_CAP				0x50
> >  #define PCIE_RC_LCR				0x7c
> >  #define PCIE_RC_LCR_MAX_LINK_SPEEDS_GEN1	0x1
> >  #define PCIE_RC_LCR_MAX_LINK_SPEEDS_GEN2	0x2
> > @@ -926,6 +927,7 @@ 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)
> > @@ -1070,6 +1072,11 @@ static int imx6_pcie_probe(struct
> platform_device *pdev)
> >  	ret = imx6_add_pcie_port(imx6_pcie, pdev);
> >  	if (ret < 0)
> >  		return ret;
> > +	if (IS_ENABLED(CONFIG_PCI_MSI)) {
> 
> CONFIG_PCI_IMX6 depends on CONFIG_PCI_MSI_IRQ_DOMAIN that in turn
> depends on CONFIG_PCI_MSI. So this condition should always be true. If so,
> you can drop this one as well.
[Richard Zhu] Thanks.
Can we have the double check here?
Thus, it's aligned to the MSI enable codes in the other place of the driver.
For example:
...
	        if (IS_ENABLED(CONFIG_PCI_MSI))
                dw_pcie_msi_init(pp);
...
Secondly, the driver has a better portability with the double check here.
How do you think about it?

> 
> > +		val = dw_pcie_readw_dbi(pci, PCI_MSI_CAP + PCI_MSI_FLAGS);
> > +		val |= PCI_MSI_FLAGS_ENABLE;
> > +		dw_pcie_writew_dbi(pci, PCI_MSI_CAP + PCI_MSI_FLAGS, val);
> > +	}
> >
> >  	return 0;
> >  }
> 
> baruch
> 
> --
> 
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