Re: [PATCH] bus: mhi: host: pci_generic: Add autosuspend_delay customized support

[Manivannan Sadhasivam <mani@kernel.org>]

On Thu, Oct 15, 2026 at 02:13:52PM +0800, Slark Xiao wrote:
> 
> At 2026-10-11 17:46:22, "Manivannan Sadhasivam" <mani@kernel.org> wrote:
> >On Thu, Oct 08, 2026 at 04:40:09PM +0800, Slark Xiao wrote:
> >> 
> >> 
> >> At 2026-09-26 19:26:15, "Manivannan Sadhasivam" <mani@kernel.org> wrote:
> >> >On Wed, Sep 23, 2026 at 09:24:55AM +0530, Krishna Chaitanya Chundru wrote:
> >> >> 
> >> >> 
> >> >> On 9/22/2026 5:09 PM, Slark Xiao wrote:
> >> >> > At 2026-09-22 12:12:35, "Krishna Chaitanya Chundru" <krishna.chundru@oss.qualcomm.com> wrote:
> >> >> >>
> >> >> >> On 9/19/2026 3:25 PM, Slark Xiao wrote:
> >> >> >>> For some WWAN device, it may get a SYS ERROR issue when resuming
> >> >> >>> from suspend state frequently. Refer to the Qualcomm Windows
> >> >> >>> driver, the default value of autosuspend_delay_ms is set as 5000
> >> >> >>> ms. But in Linux side, all WWAN device were set as 2000ms. We
> >> >> >>> tried to set this value to 5000ms and we can get a positive test
> >> >> >>> result.
> >> >> >>>
> >> >> >>> So we add a support to allow vendor to set a difference value for
> >> >> >>> specific WWAN device.
> >> >> >> you can change auto suspend delay from sysfs, please use that way instead of
> >> >> >> doing in the driver.
> >> >> >>
> >> >> >> - Krishna Chaitanya.
> >> >> > Yes, we can do this by setting the sysfs API . However, not all users 
> >> >> > are aware of this method. Additionally, this approach is only
> >> >> > effective for a single instance; it requires reconfiguration after each
> >> >> > restart, which is quite inconvenient.
> >> >> you can have udev rule to set this without any user intervention.
> >> >
> >> >We should not rely on userspace to fix the SYS_ERROR. Userspace knob should only
> >> >be exercised to customize the delay for power management purposes, not to fix
> >> >firmware crash.
> >> 
> >> >
> >> Agree. We are still working on the issue debug on the modem side. 
> >> 
> >> >First we should know whether the default delay can be increased to 5000ms for
> >> >all devices or not. If that is not desired, then we can go for Endpoint specific
> >> >delay.
> >> >
> >> >- Mani
> >> >
> >> For reference, MTK 5G modem T700 is using 5000ms as default value. And Qualcomm
> >> Windows drivers side, the default value is 5000ms as well.
> >> However, I cannot guarantee that if all MHI devices are adjusted to 5000ms, some
> >> power-sensitive devices will not oppose this change. Additional, DELL hopes that
> >> we only modify the SDX72 device while keeping the 2000ms setting for the SDX62
> >> devices, as there are currently no similar issues with the SDX62 platform.
> >> 
> >
> >I think we should know the root cause of the crash before adding my fix. Right
> >now, we only know that it is a firmware crash, but we don't know if the crash is
> >due to MHI stack or PCI bus. If it is the MHI stack, then we can quirk the
> >device in pci_generic driver. If it is a PCI bus issue, then we need to handle
> >the quirk in pci/quirks.c.
> >
> >- Mani
> We provided the crash dumps to Qualcomm for further analysis. Issue seems
> come from firmware side. Finally, Qualcomm recommend us to update this
> auto suspend delay value to 5s. Otherwise we may get a unexpected issue
> for some specific scenario.
> And currently our customer agreed that we set this value to 5s for all DW5934e
> products. So I want to add this update based on our real requirement.
> 

Sure, go ahead and respin this patch

- Mani

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