On Tue, Apr 12, 2022 at 07:55:41PM +0200, Pali Rohár wrote: > On Tuesday 12 April 2022 16:25:24 Lorenzo Pieralisi wrote: > > On Sun, Feb 20, 2022 at 08:33:45PM +0100, Marek Behún wrote: > > > From: Pali Rohár <pali@xxxxxxxxxx> > > > > > > Link training and PCIe card reset routines in Aardvark contain several > > > delays, resulting in rather slow PCIe card probing. The worst case is > > > when there is no card connected: the driver tries link training at all > > > possible speeds and waits until all timers expire. > > > > > > Since probe methods for all system devices are called sequentially, this > > > results in noticeably longer boot time. > > > > > > Move card reset and link training code from driver probe function into > > > a separate worker, so that kernel can do something different while the > > > driver is waiting during reset or training. > > > > > > On ESPRESSObin and Turris MOX this decreases boot time by 0.4s with > > > plugged PCIe card and by 2.2s if no card is connected. > > > > I believe this is what the PROBE_PREFER_ASYNCHRONOUS flag in > > struct device_driver.probe_type flag is there for unless I am > > missing something obvious here. > > > > Can you give it a try and report back please ? > > Hello Lorenzo. > > During testing patches 17 and 18 I saw that following race condition > https://lore.kernel.org/linux-pci/20210407144146.rl7x2h5l2cc3escy@pali/ > (which cause kernel oops) was triggered more often. > > I'm not sure if above race condition was fully fixed by the last > Krzysztof's patches or there is also other issue which cause oops. > > As both patches 17 and 18 are just optimizations, I would suggest to > skip it for now, until all these issues are resolved or verified that > they are not triggered anymore. > > I guess that at this time we can look at PROBE_PREFER_ASYNCHRONOUS flag > and decide how to implement this optimization. > > Do you agree, or do you have other opinion? It is fine by me - I will consider other patches in the series. Lorenzo > > Thanks, > > Lorenzo > > > > > Signed-off-by: Pali Rohár <pali@xxxxxxxxxx> > > > Signed-off-by: Marek Behún <kabel@xxxxxxxxxx> > > > --- > > > drivers/pci/controller/pci-aardvark.c | 42 ++++++++++++++++++--------- > > > 1 file changed, 28 insertions(+), 14 deletions(-) > > > > > > diff --git a/drivers/pci/controller/pci-aardvark.c b/drivers/pci/controller/pci-aardvark.c > > > index 8c9ac7766ac7..056f49d0e3a4 100644 > > > --- a/drivers/pci/controller/pci-aardvark.c > > > +++ b/drivers/pci/controller/pci-aardvark.c > > > @@ -26,6 +26,7 @@ > > > #include <linux/of_gpio.h> > > > #include <linux/of_pci.h> > > > #include <linux/timer.h> > > > +#include <linux/workqueue.h> > > > > > > #include "../pci.h" > > > #include "../pci-bridge-emul.h" > > > @@ -296,6 +297,8 @@ struct advk_pcie { > > > int link_gen; > > > bool link_was_up; > > > struct timer_list link_irq_timer; > > > + struct delayed_work probe_card_work; > > > + bool host_bridge_probed; > > > struct pci_bridge_emul bridge; > > > struct gpio_desc *reset_gpio; > > > struct clk *clk; > > > @@ -497,6 +500,21 @@ static void advk_pcie_train_link(struct advk_pcie *pcie) > > > dev_err(dev, "link never came up\n"); > > > } > > > > > > +static void advk_pcie_probe_card_work(struct work_struct *work) > > > +{ > > > + struct delayed_work *dwork = container_of(work, struct delayed_work, > > > + work); > > > + struct advk_pcie *pcie = container_of(dwork, struct advk_pcie, > > > + probe_card_work); > > > + struct pci_host_bridge *bridge = pci_host_bridge_from_priv(pcie); > > > + int ret; > > > + > > > + advk_pcie_train_link(pcie); > > > + ret = pci_host_probe(bridge); > > > + if (!ret) > > > + pcie->host_bridge_probed = true; > > > +} > > > + > > > /* > > > * Set PCIe address window register which could be used for memory > > > * mapping. > > > @@ -701,8 +719,6 @@ static void advk_pcie_setup_hw(struct advk_pcie *pcie) > > > /* Disable remaining PCIe outbound windows */ > > > for (i = pcie->wins_count; i < OB_WIN_COUNT; i++) > > > advk_pcie_disable_ob_win(pcie, i); > > > - > > > - advk_pcie_train_link(pcie); > > > } > > > > > > static int advk_pcie_check_pio_status(struct advk_pcie *pcie, bool allow_crs, u32 *val) > > > @@ -2112,14 +2128,8 @@ static int advk_pcie_probe(struct platform_device *pdev) > > > bridge->ops = &advk_pcie_ops; > > > bridge->map_irq = advk_pcie_map_irq; > > > > > > - ret = pci_host_probe(bridge); > > > - if (ret < 0) { > > > - irq_set_chained_handler_and_data(pcie->irq, NULL, NULL); > > > - advk_pcie_remove_rp_irq_domain(pcie); > > > - advk_pcie_remove_msi_irq_domain(pcie); > > > - advk_pcie_remove_irq_domain(pcie); > > > - return ret; > > > - } > > > + INIT_DELAYED_WORK(&pcie->probe_card_work, advk_pcie_probe_card_work); > > > + schedule_delayed_work(&pcie->probe_card_work, 1); > > > > > > return 0; > > > } > > > @@ -2131,11 +2141,15 @@ static int advk_pcie_remove(struct platform_device *pdev) > > > u32 val; > > > int i; > > > > > > + cancel_delayed_work_sync(&pcie->probe_card_work); > > > + > > > /* Remove PCI bus with all devices */ > > > - pci_lock_rescan_remove(); > > > - pci_stop_root_bus(bridge->bus); > > > - pci_remove_root_bus(bridge->bus); > > > - pci_unlock_rescan_remove(); > > > + if (pcie->host_bridge_probed) { > > > + pci_lock_rescan_remove(); > > > + pci_stop_root_bus(bridge->bus); > > > + pci_remove_root_bus(bridge->bus); > > > + pci_unlock_rescan_remove(); > > > + } > > > > > > /* Disable Root Bridge I/O space, memory space and bus mastering */ > > > val = advk_readl(pcie, PCIE_CORE_CMD_STATUS_REG); > > > -- > > > 2.34.1 > > >
