linux-kernel - Re: [PATCH] PCI: qcom: Skip wait for link up if global IRQ handler is present

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Message-ID: <20240920083258.rpxr6kd4onsbu73c@thinkpad>
Date: Fri, 20 Sep 2024 10:32:58 +0200
From: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
To: Krishna chaitanya chundru <quic_krichai@...cinc.com>
Cc: Jingoo Han <jingoohan1@...il.com>,
	Lorenzo Pieralisi <lpieralisi@...nel.org>,
	Krzysztof Wilczyński <kw@...ux.com>,
	Rob Herring <robh@...nel.org>, Bjorn Helgaas <bhelgaas@...gle.com>,
	quic_vbadigan@...cinc.com, quic_ramkri@...cinc.com,
	quic_nitegupt@...cinc.com, quic_skananth@...cinc.com,
	quic_vpernami@...cinc.com, quic_mrana@...cinc.com,
	linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-arm-msm@...r.kernel.org
Subject: Re: [PATCH] PCI: qcom: Skip wait for link up if global IRQ handler
 is present

On Tue, Sep 17, 2024 at 04:16:20PM +0530, Krishna chaitanya chundru wrote:
> In cases where a global IRQ handler is present to manage link up
> interrupts, it may not be necessary to wait for the link to be up
> during PCI initialization which optimizes the bootup time.
> 
> Move platform_get_irq_byname_optional() above to set bypass_link_up_wait
> before dw_pcie_host_init() as this flag is used in this function only.
> 
> And also as part of the PCIe link up event, update ICC and OPP values.
> 

This has to be a separate patch.

> Signed-off-by: Krishna chaitanya chundru <quic_krichai@...cinc.com>
> ---
>  drivers/pci/controller/dwc/pcie-designware-host.c | 3 ++-
>  drivers/pci/controller/dwc/pcie-designware.h      | 1 +
>  drivers/pci/controller/dwc/pcie-qcom.c            | 7 ++++++-
>  3 files changed, 9 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/pci/controller/dwc/pcie-designware-host.c b/drivers/pci/controller/dwc/pcie-designware-host.c
> index 3e41865c7290..e0ddfaf9f87a 100644
> --- a/drivers/pci/controller/dwc/pcie-designware-host.c
> +++ b/drivers/pci/controller/dwc/pcie-designware-host.c
> @@ -531,7 +531,8 @@ int dw_pcie_host_init(struct dw_pcie_rp *pp)
>  	}
>  
>  	/* Ignore errors, the link may come up later */
> -	dw_pcie_wait_for_link(pci);

Add a comment to clarify that the link up delay is skipped in the presence of
Link up IRQ.

This flag is not a way to just skip the link up delay for arbitrary reasons as
attempted before.

> +	if (!pp->bypass_link_up_wait)
> +		dw_pcie_wait_for_link(pci);
>  
>  	bridge->sysdata = pp;
>  
> diff --git a/drivers/pci/controller/dwc/pcie-designware.h b/drivers/pci/controller/dwc/pcie-designware.h
> index e518f81ea80c..7fe0e9b1b095 100644
> --- a/drivers/pci/controller/dwc/pcie-designware.h
> +++ b/drivers/pci/controller/dwc/pcie-designware.h
> @@ -348,6 +348,7 @@ struct dw_pcie_rp {
>  	bool			use_atu_msg;
>  	int			msg_atu_index;
>  	struct resource		*msg_res;
> +	bool			bypass_link_up_wait;

How about, 'linkup_irq'?

- Mani

>  };
>  
>  struct dw_pcie_ep_ops {
> diff --git a/drivers/pci/controller/dwc/pcie-qcom.c b/drivers/pci/controller/dwc/pcie-qcom.c
> index 88a98be930e3..bcb8c60453ba 100644
> --- a/drivers/pci/controller/dwc/pcie-qcom.c
> +++ b/drivers/pci/controller/dwc/pcie-qcom.c
> @@ -1552,6 +1552,8 @@ static irqreturn_t qcom_pcie_global_irq_thread(int irq, void *data)
>  		pci_lock_rescan_remove();
>  		pci_rescan_bus(pp->bridge->bus);
>  		pci_unlock_rescan_remove();
> +
> +		qcom_pcie_icc_opp_update(pcie);
>  	} else {
>  		dev_WARN_ONCE(dev, 1, "Received unknown event. INT_STATUS: 0x%08x\n",
>  			      status);
> @@ -1686,6 +1688,10 @@ static int qcom_pcie_probe(struct platform_device *pdev)
>  
>  	platform_set_drvdata(pdev, pcie);
>  
> +	irq = platform_get_irq_byname_optional(pdev, "global");
> +	if (irq > 0)
> +		pp->bypass_link_up_wait = true;
> +
>  	ret = dw_pcie_host_init(pp);
>  	if (ret) {
>  		dev_err(dev, "cannot initialize host\n");
> @@ -1699,7 +1705,6 @@ static int qcom_pcie_probe(struct platform_device *pdev)
>  		goto err_host_deinit;
>  	}
>  
> -	irq = platform_get_irq_byname_optional(pdev, "global");
>  	if (irq > 0) {
>  		ret = devm_request_threaded_irq(&pdev->dev, irq, NULL,
>  						qcom_pcie_global_irq_thread,
> 
> ---
> base-commit: 9aaeb87ce1e966169a57f53a02ba05b30880ffb8
> change-id: 20240911-remove_wait-ad46248dc9f0
> 
> Best regards,
> -- 
> Krishna chaitanya chundru <quic_krichai@...cinc.com>
> 

-- 
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