Messages in this thread | | | From | "Zhao, Haifeng" <> | Subject | RE: [PATCH 1/5] PCI: define a function to check and wait till port finish DPC handling | Date | Sun, 27 Sep 2020 01:53:34 +0000 |
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Andy, About the header file, yes, to keep the order. The function was already defined with #ifdef CONFIG_PCIE_DPC. As to ' readx_poll_timeout()' if there is generic one, I would like to use it. Seems there is no yet ?
Thanks, Ethan
-----Original Message----- From: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Sent: Friday, September 25, 2020 8:25 PM To: Zhao, Haifeng <haifeng.zhao@intel.com> Cc: bhelgaas@google.com; oohall@gmail.com; ruscur@russell.cc; lukas@wunner.de; stuart.w.hayes@gmail.com; mr.nuke.me@gmail.com; mika.westerberg@linux.intel.com; linux-pci@vger.kernel.org; linux-kernel@vger.kernel.org; Jia, Pei P <pei.p.jia@intel.com> Subject: Re: [PATCH 1/5] PCI: define a function to check and wait till port finish DPC handling
On Thu, Sep 24, 2020 at 10:34:19PM -0400, Ethan Zhao wrote: > Once root port DPC capability is enabled and triggered, at the > beginning of DPC is triggered, the DPC status bits are set by hardware > and then sends DPC/DLLSC/PDC interrupts to OS DPC and pciehp drivers, > it will take the port and software DPC interrupt handler 10ms to 50ms > (test data on ICX platform & stable 5.9-rc6) to complete the DPC > containment procedure till the DPC status is cleared at the end of the DPC interrupt handler. > > We use this function to check if the root port is in DPC handling > status and wait till the hardware and software completed the procedure.
> #include <linux/interrupt.h> > #include <linux/io.h> > #include <linux/resource_ext.h>
> +#include <linux/delay.h>
Keep it sorted?
> #include <uapi/linux/pci.h>
...
> +#ifdef CONFIG_PCIE_DPC > +static inline bool pci_wait_port_outdpc(struct pci_dev *pdev) { > + u16 cap = pdev->dpc_cap, status; > + u16 loop = 0; > + > + if (!cap) {
> + pci_WARN_ONCE(pdev, !cap, "No DPC capability initiated\n");
But why? Is this feature mandatory to have? Then the same question about ifdeffery, otherwise it's pretty normal to not have a feature, right?
> + return false; > + } > + pci_read_config_word(pdev, cap + PCI_EXP_DPC_STATUS, &status); > + pci_dbg(pdev, "DPC status %x, cap %x\n", status, cap);
> + while (status & PCI_EXP_DPC_STATUS_TRIGGER && loop < 100) { > + msleep(10); > + loop++; > + pci_read_config_word(pdev, cap + PCI_EXP_DPC_STATUS, &status); > + }
Can we have rather something like readx_poll_timeout() for PCI and use them here?
> + if (!(status & PCI_EXP_DPC_STATUS_TRIGGER)) { > + pci_dbg(pdev, "Out of DPC status %x, time cost %d ms\n", status, loop*10); > + return true; > + } > + pci_dbg(pdev, "Timeout to wait port out of DPC status\n"); > + return false; > +} > +#else > +static inline bool pci_wait_port_outdpc(struct pci_dev *pdev) { > + return true; > +} > +#endif > #endif /* LINUX_PCI_H */ > -- > 2.18.4 >
-- With Best Regards, Andy Shevchenko
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