Re: [BUG REPORT] MHI's resume from hibernate is broken

[Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>]

On Mon, Feb 17, 2025 at 07:35:50PM +0500, Muhammad Usama Anjum wrote:
> On 2/14/25 12:04 PM, Manivannan Sadhasivam wrote:
> > Hi,
> Thank you so much for replying.
> 
> > 
> > + ath11k list and Jeff
> > 
> > On Tue, Feb 11, 2025 at 01:15:55PM +0500, Muhammad Usama Anjum wrote:
> >> Hi,
> >>
> >> I've been digging in the MHI code to find the reason behind broken
> >> resume from hibernation for MHI. The same resume function is used
> >> for both resume from suspend and resume from hibernation. The resume
> >> from suspend works fine because at resume time the state of MHI is 
> >> MHI_STATE_M3. On the other hand, the state is MHI_STATE_RESET when
> >> we resume from hibernation.
> >>
> >> It seems resume from MHI_STATE_RESET state isn't correctly supported.
> >> The channel state is MHI_CH_STATE_ENABLED at this point. We get error
> >> while switching channel state from MHI_CH_STATE_ENABLE to
> >> MHI_CH_STATE_RUNNING. Hence, channel state change fails and later mhi
> >> resume fails as well. 
> >>
> >> I've put some debug prints to understand the issue. These may be
> >> helpful:
> >>
> >> [  669.032683] mhi_update_channel_state: switch to MHI_CH_STATE_TYPE_START[2] channel state not possible cuzof channel current state[1]. mhi state: [0] Return -EINVAL
> >> [  669.032685] mhi_prepare_channel: mhi_update_channel_state to MHI_CH_STATE_TYPE_START[2] returned -22
> >> [  669.032693] qcom_mhi_qrtr mhi0_IPCR: failed to prepare for autoqueue transfer -22
> >>
> > 
> > Thanks for the report!
> > 
> > Could you please enable the MHI and ath11k debug logs and share the full dmesg
> > to help us understand the issue better?
> The ath11k debug was already enabled. CONFIG_MHI_BUS_DEBUG wasn't enabled. 

Sorry for not being clear. I asked you to enable the dev_dbg() logs in the MHI
driver. But it is not required. See below.

> I've
> enabled it and now the hibernate is working without any issue. It is very strange
> how can CONFIG_MHI_BUS_DEBUG make any difference. I don't have much background on
> how it is helping.
> 

Probably some timing issue. But enabling the MHI debug logs could also hide the
issue. So you should disable the CONFIG_MHI_BUS_DEBUG option and collect the MHI
trace logs that we recently added.

Hope it will shed some light.

- Mani

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