Messages in this thread | | | Date | Mon, 26 Sep 2022 15:59:29 +0530 | Subject | Re: [PATCH V1] PCI: dwc: Use dev_info for PCIe link down event logging | From | Vidya Sagar <> |
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Hi, Just checking if we are good with this patch or does it need any further modifications?
Thanks, Vidya Sagar
On 9/15/2022 8:22 PM, Manivannan Sadhasivam wrote: > External email: Use caution opening links or attachments > > > On Thu, Sep 15, 2022 at 09:16:27AM -0500, Rob Herring wrote: >> On Wed, Sep 14, 2022 at 1:24 AM Manivannan Sadhasivam >> <manivannan.sadhasivam@linaro.org> wrote: >>> >>> On Tue, Sep 13, 2022 at 03:07:46PM -0500, Bjorn Helgaas wrote: >>>> On Tue, Sep 13, 2022 at 06:00:30PM +0100, Jon Hunter wrote: >>>>> On 13/09/2022 17:51, Manivannan Sadhasivam wrote: >>>>>> On Tue, Sep 13, 2022 at 03:42:37PM +0530, Vidya Sagar wrote: >>>>>>> Some of the platforms (like Tegra194 and Tegra234) have open slots and >>>>>>> not having an endpoint connected to the slot is not an error. >>>>>>> So, changing the macro from dev_err to dev_info to log the event. >>>>>> >>>>>> But the link up not happening is an actual error and -ETIMEDOUT is being >>>>>> returned. So I don't think the log severity should be changed. >>>>> >>>>> Yes it is an error in the sense it is a timeout, but reporting an error >>>>> because nothing is attached to a PCI slot seems a bit noisy. Please note >>>>> that a similar change was made by the following commit and it also seems >>>>> appropriate here ... >>>>> >>>>> commit 4b16a8227907118e011fb396022da671a52b2272 >>>>> Author: Manikanta Maddireddy <mmaddireddy@nvidia.com> >>>>> Date: Tue Jun 18 23:32:06 2019 +0530 >>>>> >>>>> PCI: tegra: Change link retry log level to debug >>>>> >>>>> >>>>> BTW, we check for error messages in the dmesg output and this is a new error >>>>> seen as of Linux v6.0 and so this was flagged in a test. We can ignore the >>>>> error, but in this case it seem more appropriate to make this a info or >>>>> debug level print. >>>> >>>> Can you tell whether there's a device present, e.g., via Slot Status >>>> Presence Detect? If there's nothing in the slot, I don't know why we >>>> would print anything at all. If a card is present but there's no >>>> link, that's probably worthy of dev_info() or even dev_err(). >>>> >>> >>> I don't think all form factors allow for the PRSNT pin to be wired up, >>> so we cannot know if the device is actually present in the slot or not all >>> the time. Maybe we should do if the form factor supports it? >>> >>>> I guess if you can tell the slot is empty, there's no point in even >>>> trying to start the link, so you could avoid both the message and the >>>> timeout by not even calling dw_pcie_wait_for_link(). >>> >>> Right. There is an overhead of waiting for ~1ms during boot. >> >> Async probe should mitigate that, right? Saravana is working toward >> making that the default instead of opt in, but you could opt in now. >> > > No. The delay is due to the DWC core waiting for link up that depends on > the PCIe device to be present on the slot. The driver probe order > doesn't apply here. > > Thanks, > Mani > >> Rob
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