linux-kernel - RE: [PATCH v1] PCI: imx6: Set MSI enable bit of RC in resume

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Message-ID: <AS8PR04MB8676A61A8C554EB0F0162C998C0E9@AS8PR04MB8676.eurprd04.prod.outlook.com>
Date:   Fri, 25 Nov 2022 02:07:19 +0000
From:   Hongxing Zhu <hongxing.zhu@....com>
To:     Hongxing Zhu <hongxing.zhu@....com>,
        "l.stach@...gutronix.de" <l.stach@...gutronix.de>,
        "bhelgaas@...gle.com" <bhelgaas@...gle.com>,
        "lorenzo.pieralisi@....com" <lorenzo.pieralisi@....com>
CC:     "linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "kernel@...gutronix.de" <kernel@...gutronix.de>,
        dl-linux-imx <linux-imx@....com>
Subject: RE: [PATCH v1] PCI: imx6: Set MSI enable bit of RC in resume

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.

Best Regards
Richard Zhu

> -----Original Message-----
> From: Richard Zhu <hongxing.zhu@....com>
> Sent: 2022年11月1日 16:00
> To: l.stach@...gutronix.de; bhelgaas@...gle.com;
> lorenzo.pieralisi@....com
> Cc: Hongxing Zhu <hongxing.zhu@....com>; linux-pci@...r.kernel.org;
> linux-arm-kernel@...ts.infradead.org; linux-kernel@...r.kernel.org;
> kernel@...gutronix.de; dl-linux-imx <linux-imx@....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@....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