linux-kernel - Re: [PATCH 1/2] soc: qcom: pd

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Message-ID: <ZsbomSG6DXTfYxXZ@hovoldconsulting.com>
Date: Thu, 22 Aug 2024 09:28:25 +0200
From: Johan Hovold <johan@...nel.org>
To: Chris Lew <quic_clew@...cinc.com>
Cc: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
	Stephan Gerhold <stephan.gerhold@...aro.org>,
	Bjorn Andersson <andersson@...nel.org>,
	Konrad Dybcio <konradybcio@...nel.org>,
	linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
	Abel Vesa <abel.vesa@...aro.org>
Subject: Re: [PATCH 1/2] soc: qcom: pd_mapper: Add X1E80100

On Tue, Jul 30, 2024 at 11:04:58PM -0700, Chris Lew wrote:

> GLINK has a concept that is called "intents". An intent is an object 
> that signifies that a remote channel is ready to receive a packet 
> through GLINK. Intents can be pre-emptively queued, or they can be 
> requested by the sending entity. GLINK will not try to send or it will 
> block until there is an intent available.
> 
> Intents are exchanged with GLINK_CMD_INTENT packets. When Linux receives 
> one of these packets we add it to an idr "riids".
> 
> Example sending call:
>      pmic_glink_send() --> rpmsg_send() --> qcom_glink_send() --> 
> __qcom_glink_send() --> qcom_glink_request_intent()
> 
> In __qcom_glink_send(), we check if there are any available intents in 
> "riids", if there aren't any intents we request an intent through 
> qcom_glink_request_intent(). This sends a GLINK_CMD_RX_INTENT_REQ packet 
> to the remote and waits for a GLINK_CMD_RX_INTENT_REQ_ACK packet in 
> return. This ack packet will have a field that says whether the intent 
> has been granted or not. When linux gets this ack packet, we will wake 
> up the thread waiting in qcom_glink_request_intent().
> 
> The ECANCELED comes from qcom_glink_request_intent() when we receive a 
> GLINK_CMD_RX_INTENT_REQ_ACK that has granted == false.
> 
> On the firmware, when a glink channel is registered they can optionally 
> fill in a handler for GLINK_CMD_RX_INTENT_REQ packets. If this handler 
> is not configured, then a default one will be used where all 
> GLINK_CMD_RX_INTENT_REQ packets will be responded with 
> GLINK_CMD_RX_INTENT_REQ_ACK and granted == false. If a channel is 
> implemented this way, then the only thing Linux can do is wait and retry 
> until the remote queues the intents on its own accord.
> 
> This would be my current guess as to what's happening based on this not 
> being consistent and only seen every couple of reboots. A stop path 
> problem sounds like it should happen every time, and we should also see 
> the remoteproc prints related to powering down the adsp. The above race 
> should be applicable to all platforms but depends on the speed of the 
> ADSP vs the CPU.

Thanks for the above. This indeed seems to match what I'm seeing as I
also reported here [1]:

[    9.539415]  30000000.remoteproc:glink-edge: qcom_glink_handle_intent_req_ack - cid = 9, granted = 0
[    9.561750] qcom_battmgr.pmic_glink_power_supply pmic_glink.power-supply.0: failed to request power notifications

[    9.448945]  30000000.remoteproc:glink-edge: qcom_glink_handle_intent_req_ack - cid = 9, granted = 0
[    9.461267] pmic_glink_altmode.pmic_glink_altmode pmic_glink.altmode.0: failed to send altmode request: 0x10 (-125)
[    9.469241] qcom,apr 30000000.remoteproc:glink-edge.adsp_apps.-1.-1: Adding APR/GPR dev: gprsvc:service:2:1
[    9.478968] pmic_glink_altmode.pmic_glink_altmode pmic_glink.altmode.0: failed to request altmode notifications: -125

I assume we do not want to have every client driver implement a retry
loop for the first communication with the remote end, so can this be
handled by the pmic_glink driver somehow? For example, by not forwarding
state changes until some generic request has gone through?

And what about the audio service errors:

	[   14.565059] PDR: avs/audio get domain list txn wait failed: -110
        [   14.571943] PDR: service lookup for avs/audio failed: -110

Does this seem to be a separate (but related) issue or just a different
symptom?

Johan


[1] https://lore.kernel.org/lkml/ZsRGV4hplvidpYji@hovoldconsulting.com/