> -----Original Message----- > From: Rob Herring <robh@xxxxxxxxxx> > Sent: 2022年4月2日 4:44 > To: Hongxing Zhu <hongxing.zhu@xxxxxxx> > Cc: l.stach@xxxxxxxxxxxxxx; bhelgaas@xxxxxxxxxx; broonie@xxxxxxxxxx; > lorenzo.pieralisi@xxxxxxx; jingoohan1@xxxxxxxxx; festevam@xxxxxxxxx; > francesco.dolcini@xxxxxxxxxxx; linux-pci@xxxxxxxxxxxxxxx; > linux-arm-kernel@xxxxxxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; > kernel@xxxxxxxxxxxxxx; dl-linux-imx <linux-imx@xxxxxxx> > Subject: Re: [PATCH v8 6/8] PCI: dwc: Add dw_pcie_host_ops.host_exit() > callback > > On Fri, Feb 25, 2022 at 11:44:25AM +0800, Richard Zhu wrote: > > When the link never comes up after ->host_init(), some drivers, > > especially those that don't support hotplug, want to turn off clocks > > and power supplies. > > Isn't supporting hotplug or not a board level decision? And hotplug doesn't > have to mean physical plug/unplug. For example, you could have a soldered > down PCIe device which needs regulators, resets, clocks, etc. > for that device to be initialized before the link comes up. If that device is > handled by a module loaded some time later, then the link may be down when > you probe. > > I think the way this all needs to work is with runtime PM. If that's all in place, > then either you shutdown clocks/power on timeout or via sysfs suspend. If > there's a child device, then that should prevent suspending. Hi Rob: Thanks a lot for your review comments. Understand what you mean. i.MX PCIe doesn't support hot-plug from chip design view. The ops.host_exit() callback is invoked only when the iMX PCIe driver hooked callback ops->start_link return an error. For the platforms, that support the hot-plug feature, they can just return one zero from their own ops->start_link. In the current situation, i.MX PCIe does just return one zero when probe failed. See the discussion and commit issued by Fabio below. https://patchwork.kernel.org/project/linux-pci/patch/1641368602-20401-6-git-send-email-hongxing.zhu@xxxxxxx/ https://patchwork.ozlabs.org/project/linux-pci/patch/20220106103645.2790803-1-festevam@xxxxxxxxx/ > > > Add a new ->host_exit() callback in dw_pcie_host_ops so these drivers > > can clean up if ->host_init() fails. > > I'm not really a fan of adding more ops nor the ops which aren't too specific > about what they do. 'init' and 'exit' can be anything. I'd rather see more > specific ops with the DWC core driver in charge of sequence of operations and > the state. Understand. i.MX PCIe can't handle the error exit properly in this case by itself. So I add one more ops.host_exit() in this series. Best Regards Richard Zhu > > Rob
