linux-kernel - Re: [PATCH v2 04/11] ASoC: cs42l42: Split probe() and remove() into stages

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Message-Id: <AB6CBB73-5124-4C3B-9F03-DB4B5092767C@cutebit.org>
Date:   Thu, 15 Sep 2022 15:45:10 +0200
From:   Martin Povišer <povik+lin@...ebit.org>
To:     Richard Fitzgerald <rf@...nsource.cirrus.com>,
        Mark Brown <broonie@...nel.org>
Cc:     James Schulman <james.schulman@...rus.com>,
        David Rhodes <david.rhodes@...rus.com>,
        Lucas Tanure <tanureal@...nsource.cirrus.com>,
        Liam Girdwood <lgirdwood@...il.com>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Charles Keepax <ckeepax@...nsource.cirrus.com>,
        ChiYuan Huang <cy_huang@...htek.com>,
        Matt Flax <flatmax@...tmax.com>,
        Lukas Bulwahn <lukas.bulwahn@...il.com>,
        Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>,
        - <patches@...nsource.cirrus.com>,
        Linux-ALSA <alsa-devel@...a-project.org>,
        devicetree@...r.kernel.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        asahi@...ts.linux.dev
Subject: Re: [PATCH v2 04/11] ASoC: cs42l42: Split probe() and remove() into
 stages


> On 15. 9. 2022, at 14:20, Richard Fitzgerald <rf@...nsource.cirrus.com> wrote:
> 
> On 15/09/2022 10:44, Martin Povišer wrote:
>> From: Richard Fitzgerald <rf@...nsource.cirrus.com>
>> To prepare for adding SoundWire the probe must be split into three
>> parts:
>> 1) The bus-specific probe
>> 2) Common bus-agnostic probe steps
>> 3) Initialization of the peripheral registers
>> Step (3) must be separate because on SoundWire devices the probe must
>> enable power supplies and release reset so that the peripheral can be
>> enumerated by the bus, but it isn't possible to access registers until
>> enumeration has completed.
>> The call to devm_snd_soc_register_component() must be done at stage (2)
>> so that it can EPROBE_DEFER if necessary. In SoundWire systems stage (3)
>> is not a probe event so a deferral at this stage would not result in
>> re-probing dependencies.
>> A new init_done flag indicates that the chip has been identified and
>> initialized. This is used to prevent cs42l42_remove(), cs42l42_suspend(),
>> cs42l42_restore() and cs42l42_irq_thread() from attempting register
>> accesses if the chip was not successfully initialized. Although this
>> cannot happen on I2C, because the entire probe would fail, it is
>> possible on SoundWire if probe succeeds but the cs42l42 is never
>> enumerated.
>> Signed-off-by: Richard Fitzgerald <rf@...nsource.cirrus.com>
>> Signed-off-by: Martin Povišer <povik+lin@...ebit.org>
>> ---
>> sound/soc/codecs/cs42l42.c | 127 +++++++++++++++++++++++++------------
>> sound/soc/codecs/cs42l42.h | 2 +
>> 2 files changed, 87 insertions(+), 42 deletions(-)
>> diff --git a/sound/soc/codecs/cs42l42.c b/sound/soc/codecs/cs42l42.c
>> index 11cb659f03e0..427b29db2252 100644
>> --- a/sound/soc/codecs/cs42l42.c
>> +++ b/sound/soc/codecs/cs42l42.c
>> @@ -1627,7 +1627,7 @@ static irqreturn_t cs42l42_irq_thread(int irq, void *data)
>> 	int report = 0;
>> 	mutex_lock(&cs42l42->irq_lock);
>> -	if (cs42l42->suspended) {
>> +	if (cs42l42->suspended || !cs42l42->init_done) {
>> 		mutex_unlock(&cs42l42->irq_lock);
>> 		return IRQ_NONE;
>> 	}
> 
> This doesn't apply to broonie/for-next. Needs rebasing onto commit:
> ea75deef1a73 ("ASoC: cs42l42: Only report button state if there was a
> button interrupt")

It did apply to broonie/for-6.1 roughly at the time of posting, but
since then the merge commit 12e51866c79f ("ASoC/qcom/arm64: Qualcomm
ADSP DTS and binding fixes”) brought in changes into broonie/for-6.1
from elsewhere, I guess from broonie/for-next. (I am not sure this
was intentional.)

Since the series still applies in a 3-way automerge (git am -3) on
top of the new for-6.1 or for-next, I checked the automerge result
and also considering the other commit ea75deef1a73 touches an
unrelated part of cs42l42_irq_thread, I am not considering this an
issue, that is unless Mark says it is.

Martin