linux-kernel - Re: [PATCH 3/6] PCI: tegra: Add support for PCIe endpoint mode in Tegra194

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Date:   Fri, 29 Nov 2019 18:52:47 +0530
From:   Vidya Sagar <vidyas@...dia.com>
To:     Bjorn Helgaas <helgaas@...nel.org>
CC:     <lorenzo.pieralisi@....com>, <robh+dt@...nel.org>,
        <thierry.reding@...il.com>, <jonathanh@...dia.com>,
        <andrew.murray@....com>, <kishon@...com>,
        <gustavo.pimentel@...opsys.com>, <linux-pci@...r.kernel.org>,
        <devicetree@...r.kernel.org>, <linux-tegra@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>, <kthota@...dia.com>,
        <mmaddireddy@...dia.com>, <sagar.tv@...il.com>
Subject: Re: [PATCH 3/6] PCI: tegra: Add support for PCIe endpoint mode in
 Tegra194

On 11/27/2019 3:07 AM, Bjorn Helgaas wrote:
> On Fri, Nov 22, 2019 at 04:15:02PM +0530, Vidya Sagar wrote:
>> Add support for the endpoint mode of Synopsys DesignWare core based
>> dual mode PCIe controllers present in Tegra194 SoC.
> 
>> +static irqreturn_t tegra_pcie_ep_irq_handler(struct tegra_pcie_dw *pcie)
>> +{
>> +	struct dw_pcie_ep *ep = &pcie->pci.ep;
>> +	u32 val, tmp;
>> +
>> +	val = appl_readl(pcie, APPL_INTR_STATUS_L0);
>> +	if (val & APPL_INTR_STATUS_L0_LINK_STATE_INT) {
>> +		val = appl_readl(pcie, APPL_INTR_STATUS_L1_0_0);
>> +		appl_writel(pcie, val, APPL_INTR_STATUS_L1_0_0);
>> +		if (val & APPL_INTR_STATUS_L1_0_0_HOT_RESET_DONE) {
>> +			/* clear any stale PEX_RST interrupt */
>> +			if (!kfifo_put(&pcie->event_fifo, EP_HOT_RST_DONE)) {
>> +				dev_err(pcie->dev, "EVENT FIFO is full\n");
>> +				return IRQ_HANDLED;
>> +			}
>> +			wake_up(&pcie->wq);
>> +		}
>> +		if (val & APPL_INTR_STATUS_L1_0_0_RDLH_LINK_UP_CHGED) {
>> +			tmp = appl_readl(pcie, APPL_LINK_STATUS);
>> +			if (tmp & APPL_LINK_STATUS_RDLH_LINK_UP) {
>> +				dev_info(pcie->dev, "Link is up with Host\n");
>> +				dw_pcie_ep_linkup(ep);
>> +			}
>> +		}
>> +	} else if (val & APPL_INTR_STATUS_L0_PCI_CMD_EN_INT) {
> 
> Is it really the case that only one of
> APPL_INTR_STATUS_L0_LINK_STATE_INT and
> APPL_INTR_STATUS_L0_PCI_CMD_EN_INT can be set?
Not really.

> 
> If it's possible that both could be set, maybe this should be
> something like this?
> 
>    int spurious = 1;
> 
>    if (val & APPL_INTR_STATUS_L0_LINK_STATE_INT) {
>      ...
>      spurious = 0;
>    }
>    if (val & APPL_INTR_STATUS_L0_PCI_CMD_EN_INT) {
>      ...
>      spurious = 0;
>    }
> 
>    if (spurious) {
>      dev_warn(...)
>    }
I'll take care of this in the next patch series.

> 
>> +		val = appl_readl(pcie, APPL_INTR_STATUS_L1_15);
>> +		appl_writel(pcie, val, APPL_INTR_STATUS_L1_15);
>> +		if (val & APPL_INTR_STATUS_L1_15_CFG_BME_CHGED) {
>> +			if (!kfifo_put(&pcie->event_fifo, EP_BME_CHANGE)) {
>> +				dev_err(pcie->dev, "EVENT FIFO is full\n");
>> +				return IRQ_HANDLED;
>> +			}
>> +			wake_up(&pcie->wq);
>> +		}
>> +	} else {
>> +		dev_warn(pcie->dev, "Random interrupt (STATUS = 0x%08X)\n",
>> +			 val);
>> +		appl_writel(pcie, val, APPL_INTR_STATUS_L0);
>> +	}
>> +
>> +	return IRQ_HANDLED;
>> +}
> 
>> +static int tegra_pcie_ep_work_thread(void *p)
>> +{
>> +	struct tegra_pcie_dw *pcie = (struct tegra_pcie_dw *)p;
>> +	u32 event;
>> +
>> +	while (true) {
>> +		wait_event_interruptible(pcie->wq,
>> +					 !kfifo_is_empty(&pcie->event_fifo));
>> +
>> +		if (kthread_should_stop())
>> +			break;
>> +
>> +		if (!kfifo_get(&pcie->event_fifo, &event)) {
>> +			dev_warn(pcie->dev, "EVENT FIFO is empty\n");
>> +			continue;
>> +		}
>> +
>> +		switch (event) {
>> +		case EP_PEX_RST_DEASSERT:
>> +			dev_info(pcie->dev, "EVENT: EP_PEX_RST_DEASSERT\n");
>> +			pex_ep_event_pex_rst_deassert(pcie);
>> +			break;
>> +
>> +		case EP_PEX_RST_ASSERT:
>> +			dev_info(pcie->dev, "EVENT: EP_PEX_RST_ASSERT\n");
>> +			pex_ep_event_pex_rst_assert(pcie);
>> +			break;
>> +
>> +		case EP_HOT_RST_DONE:
>> +			dev_info(pcie->dev, "EVENT: EP_HOT_RST_DONE\n");
>> +			pex_ep_event_hot_rst_done(pcie);
>> +			break;
>> +
>> +		case EP_BME_CHANGE:
>> +			dev_info(pcie->dev, "EVENT: EP_BME_CHANGE\n");
>> +			pex_ep_event_bme_change(pcie);
>> +			break;
>> +
>> +		case EP_EVENT_EXIT:
>> +			dev_info(pcie->dev, "EVENT: EP_EVENT_EXIT\n");
>> +			return 0;
>> +
>> +		default:
>> +			dev_warn(pcie->dev, "Invalid PCIe EP event\n");
> 
> Maybe include the invalid event value in the message?
I'll take care of this in the next patch series

> 
>> +			break;
>> +		}
>> +	}
>> +
>> +	return 0;
>> +}