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

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Message-ID: <20250220075034.unsd5cq7xkip2by6@thinkpad>
Date: Thu, 20 Feb 2025 13:20:34 +0530
From: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
To: Muhammad Usama Anjum <Usama.Anjum@...labora.com>
Cc: "David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	Johan Hovold <johan@...nel.org>,
	Loic Poulain <loic.poulain@...aro.org>,
	linux-arm-msm@...r.kernel.org, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org, mhi@...ts.linux.dev,
	kernel@...labora.com, ath11k@...ts.infradead.org,
	jjohnson@...nel.org
Subject: Re: [BUG REPORT] MHI's resume from hibernate is broken

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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