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From:   Baruch Siach <baruch@tkos.co.il>
To:     Richard Zhu <hongxing.zhu@nxp.com>
Cc:     "bhelgaas\@google.com" <bhelgaas@google.com>,
        "lorenzo.pieralisi\@arm.com" <lorenzo.pieralisi@arm.com>,
        "l.stach\@pengutronix.de" <l.stach@pengutronix.de>,
        "andrew.smirnov\@gmail.com" <andrew.smirnov@gmail.com>,
        "linux-pci\@vger.kernel.org" <linux-pci@vger.kernel.org>,
        "linux-kernel\@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "linux-arm-kernel\@lists.infradead.org" 
        <linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH] PCI: imx: make msi work without pcieportbus
In-reply-to: <1544681043-3792-1-git-send-email-hongxing.zhu@nxp.com>
Date:   Thu, 13 Dec 2018 08:36:39 +0200
Message-ID: <874lbi6ih4.fsf@tkos.co.il>
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Sender: linux-kernel-owner@vger.kernel.org
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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@nxp.com>
> ---
>  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?

> +			dw_pcie_writew_dbi(pci, PCI_MSI_CAP +
> +					PCI_MSI_FLAGS, val);
> +		}
> +	}
>  
>  	return 0;
>  }

baruch

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