linux-kernel - Re: [PATCH v11 04/11] PCI: brcmstb: Add suspend and resume pm

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Message-ID: <20200910155637.GA423872@bogus>
Date:   Thu, 10 Sep 2020 09:56:37 -0600
From:   Rob Herring <robh@...nel.org>
To:     Jim Quinlan <james.quinlan@...adcom.com>
Cc:     linux-pci@...r.kernel.org,
        Nicolas Saenz Julienne <nsaenzjulienne@...e.de>,
        Christoph Hellwig <hch@....de>,
        Robin Murphy <robin.murphy@....com>,
        bcm-kernel-feedback-list@...adcom.com,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        "moderated list:BROADCOM BCM2711/BCM2835 ARM ARCHITECTURE" 
        <linux-rpi-kernel@...ts.infradead.org>,
        "moderated list:BROADCOM BCM2711/BCM2835 ARM ARCHITECTURE" 
        <linux-arm-kernel@...ts.infradead.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v11 04/11] PCI: brcmstb: Add suspend and resume pm_ops

On Mon, Aug 24, 2020 at 03:30:17PM -0400, Jim Quinlan wrote:
> From: Jim Quinlan <jquinlan@...adcom.com>
> 
> Broadcom Set-top (BrcmSTB) boards typically support S2, S3, and S5 suspend
> and resume.  Now the PCIe driver may do so as well.
> 
> Signed-off-by: Jim Quinlan <jquinlan@...adcom.com>
> Acked-by: Florian Fainelli <f.fainelli@...il.com>
> ---
>  drivers/pci/controller/pcie-brcmstb.c | 47 +++++++++++++++++++++++++++
>  1 file changed, 47 insertions(+)
> 
> diff --git a/drivers/pci/controller/pcie-brcmstb.c b/drivers/pci/controller/pcie-brcmstb.c
> index c2b3d2946a36..3d588ab7a6dd 100644
> --- a/drivers/pci/controller/pcie-brcmstb.c
> +++ b/drivers/pci/controller/pcie-brcmstb.c
> @@ -978,6 +978,47 @@ static void brcm_pcie_turn_off(struct brcm_pcie *pcie)
>  	brcm_pcie_bridge_sw_init_set(pcie, 1);
>  }
>  
> +static int brcm_pcie_suspend(struct device *dev)
> +{
> +	struct brcm_pcie *pcie = dev_get_drvdata(dev);
> +
> +	brcm_pcie_turn_off(pcie);
> +	clk_disable_unprepare(pcie->clk);
> +
> +	return 0;
> +}
> +
> +static int brcm_pcie_resume(struct device *dev)
> +{
> +	struct brcm_pcie *pcie = dev_get_drvdata(dev);
> +	void __iomem *base;
> +	u32 tmp;
> +	int ret;
> +
> +	base = pcie->base;
> +	clk_prepare_enable(pcie->clk);
> +
> +	/* Take bridge out of reset so we can access the SERDES reg */
> +	brcm_pcie_bridge_sw_init_set(pcie, 0);
> +
> +	/* SERDES_IDDQ = 0 */
> +	tmp = readl(base + PCIE_MISC_HARD_PCIE_HARD_DEBUG);
> +	u32p_replace_bits(&tmp, 0, PCIE_MISC_HARD_PCIE_HARD_DEBUG_SERDES_IDDQ_MASK);
> +	writel(tmp, base + PCIE_MISC_HARD_PCIE_HARD_DEBUG);
> +
> +	/* wait for serdes to be stable */
> +	udelay(100);

Really needs to be a spinloop?

> +
> +	ret = brcm_pcie_setup(pcie);
> +	if (ret)
> +		return ret;
> +
> +	if (pcie->msi)
> +		brcm_msi_set_regs(pcie->msi);
> +
> +	return 0;
> +}
> +
>  static void __brcm_pcie_remove(struct brcm_pcie *pcie)
>  {
>  	brcm_msi_remove(pcie);
> @@ -1087,12 +1128,18 @@ static int brcm_pcie_probe(struct platform_device *pdev)
>  
>  MODULE_DEVICE_TABLE(of, brcm_pcie_match);
>  
> +static const struct dev_pm_ops brcm_pcie_pm_ops = {
> +	.suspend_noirq = brcm_pcie_suspend,
> +	.resume_noirq = brcm_pcie_resume,

Why do you need interrupts disabled? There's 39 cases of .suspend_noirq 
and 1352 of .suspend in the tree.

Is doing a clk unprepare even safe in .suspend_noirq? IIRC, 
prepare/unprepare can sleep.

> +};
> +
>  static struct platform_driver brcm_pcie_driver = {
>  	.probe = brcm_pcie_probe,
>  	.remove = brcm_pcie_remove,
>  	.driver = {
>  		.name = "brcm-pcie",
>  		.of_match_table = brcm_pcie_match,
> +		.pm = &brcm_pcie_pm_ops,
>  	},
>  };
>  module_platform_driver(brcm_pcie_driver);
> -- 
> 2.17.1
>