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    SubjectRe: [PATCH V3 5/5] PCI: tegra: Add support for PCIe endpoint mode in Tegra194
    On Mon, Jan 13, 2020 at 11:44:11PM +0530, Vidya Sagar wrote:
    > Add support for the endpoint mode of Synopsys DesignWare core based
    > dual mode PCIe controllers present in Tegra194 SoC.
    >
    > Signed-off-by: Vidya Sagar <vidyas@nvidia.com>
    > ---
    > V3:
    > * Addressed Thierry's review comments

    I need his ACK to merge this series.

    [...]

    > +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: %u\n",
    > + event);
    > + break;
    > + }
    > + }
    > +
    > + return 0;
    > +}
    > +
    > +static irqreturn_t tegra_pcie_ep_pex_rst_irq(int irq, void *arg)
    > +{
    > + struct tegra_pcie_dw *pcie = arg;
    > +
    > + if (gpiod_get_value(pcie->pex_rst_gpiod)) {
    > + if (!kfifo_put(&pcie->event_fifo, EP_PEX_RST_ASSERT)) {
    > + dev_err(pcie->dev, "EVENT FIFO is full\n");
    > + return IRQ_HANDLED;
    > + }
    > + } else {
    > + if (!kfifo_put(&pcie->event_fifo, EP_PEX_RST_DEASSERT)) {
    > + dev_err(pcie->dev, "EVENT FIFO is full\n");
    > + return IRQ_HANDLED;
    > + }
    > + }
    > +
    > + wake_up(&pcie->wq);
    > +
    > + return IRQ_HANDLED;
    > +}
    > +

    [...]

    > +static int tegra_pcie_config_ep(struct tegra_pcie_dw *pcie,
    > + struct platform_device *pdev)
    > +{
    > + struct dw_pcie *pci = &pcie->pci;
    > + struct device *dev = pcie->dev;
    > + struct dw_pcie_ep *ep;
    > + struct resource *res;
    > + char *name;
    > + int ret;
    > +
    > + ep = &pci->ep;
    > + ep->ops = &pcie_ep_ops;
    > +
    > + res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "addr_space");
    > + if (!res)
    > + return -EINVAL;
    > +
    > + ep->phys_base = res->start;
    > + ep->addr_size = resource_size(res);
    > + ep->page_size = SZ_64K;
    > +
    > + ret = gpiod_set_debounce(pcie->pex_rst_gpiod, PERST_DEBOUNCE_TIME);
    > + if (ret < 0) {
    > + dev_err(dev, "Failed to set PERST GPIO debounce time: %d\n",
    > + ret);
    > + return ret;
    > + }
    > +
    > + ret = gpiod_to_irq(pcie->pex_rst_gpiod);
    > + if (ret < 0) {
    > + dev_err(dev, "Failed to get IRQ for PERST GPIO: %d\n", ret);
    > + return ret;
    > + }
    > + pcie->pex_rst_irq = (unsigned int)ret;
    > +
    > + name = devm_kasprintf(dev, GFP_KERNEL, "tegra_pcie_%u_pex_rst_irq",
    > + pcie->cid);
    > + if (!name) {
    > + dev_err(dev, "Failed to create PERST IRQ string\n");
    > + return -ENOMEM;
    > + }
    > +
    > + irq_set_status_flags(pcie->pex_rst_irq, IRQ_NOAUTOEN);
    > +
    > + ret = devm_request_irq(dev, pcie->pex_rst_irq,
    > + tegra_pcie_ep_pex_rst_irq,
    > + IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING,
    > + name, (void *)pcie);

    I have the impression that a threaded IRQ is what you need, which
    will also remove some boilerplate in the process. Any reason why
    you can't use a threaded IRQ instead of a standalone kthread ?

    Thanks,
    Lorenzo

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