RE: [PATCH] PCI: imx: make msi work without pcieportbus
From: Richard Zhu
Date: Thu Dec 13 2018 - 02:22:34 EST
> -----Original Message-----
> From: Baruch Siach [mailto:baruch@xxxxxxxxxx]
> Sent: 2018年12月13日 14:37
> To: Richard Zhu <hongxing.zhu@xxxxxxx>
> Cc: bhelgaas@xxxxxxxxxx; lorenzo.pieralisi@xxxxxxx;
> l.stach@xxxxxxxxxxxxxx; andrew.smirnov@xxxxxxxxx;
> linux-pci@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx;
> linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
> Subject: Re: [PATCH] PCI: imx: make msi work without pcieportbus
>
> Hi Richard,
>
> Thanks for debugging this issue. One question below.
>
> 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.
> > Make a double check on this bit, and assert it when it is not set and
> > 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@xxxxxxx>
> > ---
> > drivers/pci/controller/dwc/pci-imx6.c | 10 ++++++++++
> > 1 file changed, 10 insertions(+)
> >
> > diff --git a/drivers/pci/controller/dwc/pci-imx6.c
> > b/drivers/pci/controller/dwc/pci-imx6.c
> > index 26087b3..6c3e56b 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 +1072,14 @@ 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)) {
> > + val = dw_pcie_readw_dbi(pci, PCI_MSI_CAP + PCI_MSI_FLAGS);
> > + if ((val & PCI_MSI_FLAGS_ENABLE) == 0) {
> > + val |= PCI_MSI_FLAGS_ENABLE;
>
> Why not assert the PCI_MSI_FLAGS_ENABLE flag unconditionally here?
[Richard Zhu] Thanks for your kindly review.
It's more efficient to set it unconditionally.
I would change it in next version.
>
> > + dw_pcie_writew_dbi(pci, PCI_MSI_CAP +
> > + PCI_MSI_FLAGS, val);
> > + }
> > + }
> >
> > return 0;
> > }
>
> baruch
>
> --
>
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