linux-kernel - Re: [PATCH v7 2/4] PCI: qcom-ep: Add support for D-state change notification

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Message-ID: <4662b4fb-8ef2-4a4b-adef-e862090defd7@quicinc.com>
Date: Tue, 23 Jul 2024 09:07:32 +0530
From: Yogesh Jadav <quic_yjadav@...cinc.com>
To: Krishna chaitanya chundru <quic_krichai@...cinc.com>,
        "Manivannan
 Sadhasivam" <manivannan.sadhasivam@...aro.org>,
        Krzysztof Wilczyński <kw@...ux.com>,
        Kishon Vijay Abraham I
	<kishon@...nel.org>,
        Bjorn Helgaas <bhelgaas@...gle.com>, Jonathan Corbet
	<corbet@....net>,
        Lorenzo Pieralisi <lpieralisi@...nel.org>,
        Rob Herring
	<robh@...nel.org>
CC: <linux-pci@...r.kernel.org>, <linux-doc@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <linux-arm-msm@...r.kernel.org>,
        <mhi@...ts.linux.dev>, <quic_vbadigan@...cinc.com>,
        <quic_ramkri@...cinc.com>, <quic_nitegupt@...cinc.com>,
        <quic_skananth@...cinc.com>, <quic_parass@...cinc.com>,
        Manivannan Sadhasivam
	<mani@...nel.org>
Subject: Re: [PATCH v7 2/4] PCI: qcom-ep: Add support for D-state change
 notification



On 7/10/2024 4:38 PM, Krishna chaitanya chundru wrote:
> Add support to pass D-state change notification to Endpoint
> function driver.
> Read perst value to determine if the link is in D3Cold/D3hot.
> 
> Reviewed-by: Manivannan Sadhasivam <mani@...nel.org>
> Signed-off-by: Krishna chaitanya chundru <quic_krichai@...cinc.com>
> ---
>   drivers/pci/controller/dwc/pcie-qcom-ep.c | 8 +++++++-
>   1 file changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/pci/controller/dwc/pcie-qcom-ep.c b/drivers/pci/controller/dwc/pcie-qcom-ep.c
> index 236229f66c80..817fad805c51 100644
> --- a/drivers/pci/controller/dwc/pcie-qcom-ep.c
> +++ b/drivers/pci/controller/dwc/pcie-qcom-ep.c
> @@ -648,6 +648,7 @@ static irqreturn_t qcom_pcie_ep_global_irq_thread(int irq, void *data)
>   	struct device *dev = pci->dev;
>   	u32 status = readl_relaxed(pcie_ep->parf + PARF_INT_ALL_STATUS);
>   	u32 mask = readl_relaxed(pcie_ep->parf + PARF_INT_ALL_MASK);
> +	pci_power_t state;
>   	u32 dstate, val;
>   
>   	writel_relaxed(status, pcie_ep->parf + PARF_INT_ALL_CLEAR);
> @@ -671,11 +672,16 @@ static irqreturn_t qcom_pcie_ep_global_irq_thread(int irq, void *data)
>   		dstate = dw_pcie_readl_dbi(pci, DBI_CON_STATUS) &
>   					   DBI_CON_STATUS_POWER_STATE_MASK;
>   		dev_dbg(dev, "Received D%d state event\n", dstate);
> -		if (dstate == 3) {
> +		state = dstate;
Can we use some meaningful name for variable "state" ? There is 
different purpose of variable "state" and "dstate" which is not getting 
reflected by looking variable names.

- Yogesh
> +		if (dstate == PCI_D3hot) {
>   			val = readl_relaxed(pcie_ep->parf + PARF_PM_CTRL);
>   			val |= PARF_PM_CTRL_REQ_EXIT_L1;
>   			writel_relaxed(val, pcie_ep->parf + PARF_PM_CTRL);
> +
> +			if (gpiod_get_value(pcie_ep->reset))
> +				state = PCI_D3cold;
>   		}
> +		pci_epc_dstate_notify(pci->ep.epc, state);
>   	} else if (FIELD_GET(PARF_INT_ALL_LINK_UP, status)) {
>   		dev_dbg(dev, "Received Linkup event. Enumeration complete!\n");
>   		dw_pcie_ep_linkup(&pci->ep);
>