linux-kernel - Re: [PATCH V2 1/2] soc: qcom-geni-se: Cleanup the code to remove proxy votes

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Message-ID: <YFOKQKlI3MjMouEA@google.com>
Date:   Thu, 18 Mar 2021 10:13:36 -0700
From:   Matthias Kaehlcke <mka@...omium.org>
To:     Roja Rani Yarubandi <rojay@...eaurora.org>
Cc:     agross@...nel.org, bjorn.andersson@...aro.org,
        gregkh@...uxfoundation.org, robh+dt@...nel.org,
        linux-serial@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        Rajendra Nayak <rnayak@...eaurora.org>,
        akashast@...eaurora.org, msavaliy@....qualcomm.com
Subject: Re: [PATCH V2 1/2] soc: qcom-geni-se: Cleanup the code to remove
 proxy votes

On Thu, Mar 18, 2021 at 04:40:08PM +0530, Roja Rani Yarubandi wrote:
> ICC core and platforms drivers supports sync_state feature, which
> ensures that the default ICC BW votes from the bootloader is not
> removed until all it's consumers are probes.
> 
> The proxy votes were needed in case other QUP child drivers
> I2C, SPI probes before UART, they can turn off the QUP-CORE clock
> which is shared resources for all QUP driver, this causes unclocked
> access to HW from earlycon.
> 
> Given above support from ICC there is no longer need to maintain
> proxy votes on QUP-CORE ICC node from QUP wrapper driver for early
> console usecase, the default votes won't be removed until real
> console is probed.
> 
> Signed-off-by: Roja Rani Yarubandi <rojay@...eaurora.org>
> Signed-off-by: Akash Asthana <akashast@...eaurora.org>

I suggest to mention that this is essentially a revert of commit
048eb908a1f2 ("soc: qcom-geni-se: Add interconnect support to fix
earlycon crash"). This makes the life of reviewers easier and it's
also good to have the reference in the git history.

You could also mention commit 7d3b0b0d8184 ("interconnect: qcom:
Use icc_sync_state") in the intro.

I tried to test by first reproducing the original issue without
'sync_state' in the ICC, but wasn't successful, probably something
changed in the boot/ICC timing in the meantime ¯\_(ツ)_/¯.

Reviewed-by: Matthias Kaehlcke <mka@...omium.org>