On Thu, Aug 21, 2025 at 05:44:00AM +0000, Hongxing Zhu wrote: > > -----Original Message----- > > From: Bjorn Helgaas <helgaas@xxxxxxxxxx> > > Sent: 2025年8月20日 3:07 > > To: Hongxing Zhu <hongxing.zhu@xxxxxxx> > > Cc: Frank Li <frank.li@xxxxxxx>; jingoohan1@xxxxxxxxx; > > l.stach@xxxxxxxxxxxxxx; lpieralisi@xxxxxxxxxx; kwilczynski@xxxxxxxxxx; > > mani@xxxxxxxxxx; robh@xxxxxxxxxx; bhelgaas@xxxxxxxxxx; > > shawnguo@xxxxxxxxxx; s.hauer@xxxxxxxxxxxxxx; kernel@xxxxxxxxxxxxxx; > > festevam@xxxxxxxxx; linux-pci@xxxxxxxxxxxxxxx; > > linux-arm-kernel@xxxxxxxxxxxxxxxxxxx; imx@xxxxxxxxxxxxxxx; > > linux-kernel@xxxxxxxxxxxxxxx > > Subject: Re: [RESEND v3 4/5] PCI: dwc: Skip PME_Turn_Off message if there is > > no endpoint connected > > > > On Mon, Aug 18, 2025 at 03:32:04PM +0800, Richard Zhu wrote: > > > Skip PME_Turn_Off message if there is no endpoint connected. > > > > What's the value of doing this? Is this to make something faster? If so, > > what and by how much? > > > > Or does it fix something that's currently broken? > > > > Seems like the discussion at > > https://lore.kern/ > > el.org%2Flinux-pci%2F20241107084455.3623576-1-hongxing.zhu%40nxp.com% > > 2Ft%2F%23u&data=05%7C02%7Chongxing.zhu%40nxp.com%7Ced46fe10aeb74 > > 21c88a508dddf53a24f%7C686ea1d3bc2b4c6fa92cd99c5c301635%7C0%7C0%7 > > C638912272493755203%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOn > > RydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ% > > 3D%3D%7C0%7C%7C%7C&sdata=lIE7%2FlS5jiGxGPGVm5Hr5efpMbT19CLqrwu > > YNvAEdLY%3D&reserved=0 > > might be relevant. > > > > This commit log only restates what the code does. In my opinion we need > > actual justification for making this change. > Hi Bjorn: > Thanks for your comments. > This commit is mainly used to fix suspend/resume broken on i.MX7D PCIe. > A chip freeze is observed on i.MX7D when PCIe RC kicks off the PM_PME message > and no any devices are connected on the port. > > Because i.MX7D is a very old design, and out of IP design technical support. > I don't know what's going on inside the PCIe IP design when kick off the > PM_PME message. > > From SW perspective view, what I can do is to find out a quirk method to > workaround this broken. Hope this can clear up your confusions. OK, will look for some of this background in the commit log of the next version.
