linux-kernel - RE: [PATCH 1/5 V2] PCI: define a function to check and wait till port finish DPC handling

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Message-ID: <MWHPR11MB1696E70F1DFFFD0F1B1AE55297340@MWHPR11MB1696.namprd11.prod.outlook.com>
Date:   Sun, 27 Sep 2020 06:43:57 +0000
From:   "Zhao, Haifeng" <haifeng.zhao@...el.com>
To:     Christoph Hellwig <hch@...radead.org>
CC:     "bhelgaas@...gle.com" <bhelgaas@...gle.com>,
        "oohall@...il.com" <oohall@...il.com>,
        "ruscur@...sell.cc" <ruscur@...sell.cc>,
        "lukas@...ner.de" <lukas@...ner.de>,
        "andriy.shevchenko@...ux.intel.com" 
        <andriy.shevchenko@...ux.intel.com>,
        "stuart.w.hayes@...il.com" <stuart.w.hayes@...il.com>,
        "mr.nuke.me@...il.com" <mr.nuke.me@...il.com>,
        "mika.westerberg@...ux.intel.com" <mika.westerberg@...ux.intel.com>,
        "linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "Jia, Pei P" <pei.p.jia@...el.com>,
        "ashok.raj@...ux.intel.com" <ashok.raj@...ux.intel.com>,
        "Kuppuswamy, Sathyanarayanan" <sathyanarayanan.kuppuswamy@...el.com>
Subject: RE: [PATCH 1/5 V2] PCI: define a function to check and wait till port
 finish DPC handling

Yep, I am think the same question, is there any other files better to put this function ?
How  about pci.c ?

Thanks,
Ethan

-----Original Message-----
From: Christoph Hellwig <hch@...radead.org> 
Sent: Sunday, September 27, 2020 2:24 PM
To: Zhao, Haifeng <haifeng.zhao@...el.com>
Cc: bhelgaas@...gle.com; oohall@...il.com; ruscur@...sell.cc; lukas@...ner.de; andriy.shevchenko@...ux.intel.com; stuart.w.hayes@...il.com; mr.nuke.me@...il.com; mika.westerberg@...ux.intel.com; linux-pci@...r.kernel.org; linux-kernel@...r.kernel.org; Jia, Pei P <pei.p.jia@...el.com>; ashok.raj@...ux.intel.com; Kuppuswamy, Sathyanarayanan <sathyanarayanan.kuppuswamy@...el.com>
Subject: Re: [PATCH 1/5 V2] PCI: define a function to check and wait till port finish DPC handling

> +#ifdef CONFIG_PCIE_DPC
> +static inline bool pci_wait_port_outdpc(struct pci_dev *pdev) {
> +	u16 cap = pdev->dpc_cap, status;
> +	u16 loop = 0;
> +
> +	if (!cap) {
> +		pci_WARN_ONCE(pdev, !cap, "No DPC capability initiated\n");
> +		return false;
> +	}
> +	pci_read_config_word(pdev, cap + PCI_EXP_DPC_STATUS, &status);
> +	pci_dbg(pdev, "DPC status %x, cap %x\n", status, cap);
> +	while (status & PCI_EXP_DPC_STATUS_TRIGGER && loop < 100) {
> +		msleep(10);
> +		loop++;
> +		pci_read_config_word(pdev, cap + PCI_EXP_DPC_STATUS, &status);
> +	}
> +	if (!(status & PCI_EXP_DPC_STATUS_TRIGGER)) {
> +		pci_dbg(pdev, "Out of DPC %x, cost %d ms\n", status, loop*10);
> +		return true;
> +	}
> +	pci_dbg(pdev, "Timeout to wait port out of DPC status\n");
> +	return false;
> +}

I don't think that there is any good reason to have this as an inline function.