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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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