Messages in this thread | | | Date | Tue, 30 Mar 2021 15:25:58 +0530 | From | Sai Prakash Ranjan <> | Subject | Re: [PATCH v1] usb: dwc3: core: Add shutdown callback for dwc3 |
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On 2021-03-30 14:37, Greg Kroah-Hartman wrote: > On Tue, Mar 30, 2021 at 02:12:04PM +0530, Sandeep Maheswaram wrote: >> >> On 3/26/2021 7:07 PM, Greg Kroah-Hartman wrote: >> > On Wed, Mar 24, 2021 at 12:57:32AM +0530, Sandeep Maheswaram wrote: >> > > This patch adds a shutdown callback to USB DWC core driver to ensure that >> > > it is properly shutdown in reboot/shutdown path. This is required >> > > where SMMU address translation is enabled like on SC7180 >> > > SoC and few others. If the hardware is still accessing memory after >> > > SMMU translation is disabled as part of SMMU shutdown callback in >> > > system reboot or shutdown path, then IOVAs(I/O virtual address) >> > > which it was using will go on the bus as the physical addresses which >> > > might result in unknown crashes (NoC/interconnect errors). >> > > >> > > Previously this was added in dwc3 qcom glue driver. >> > > https://patchwork.kernel.org/project/linux-arm-msm/list/?series=382449 >> > > But observed kernel panic as glue driver shutdown getting called after >> > > iommu shutdown. As we are adding iommu nodes in dwc core node >> > > in device tree adding shutdown callback in core driver seems correct. >> > So shouldn't you also remove this from the qcom glue driver at the same >> > time? Please submit both as a patch series. >> > >> > thanks, >> > >> > greg k-h >> >> Hi Greg, >> >> The qcom glue driver patch is not merged yet. I have just mentioned >> for it for reference. > > You know that we can not add callbacks for no in-kernel user, so what > good is this patch for now? >
What in-kernel user? Since when does shutdown callback need an in-kernel user? When you reboot or shutdown a system, it gets called. The reason why the shutdown callback is needed is provided in the commit text.
Confused, Sai Prakash Ranjan
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