linux-kernel - Re: [PATCH 2/9] ASoC: amd: ps: handle soundwire interrupts in acp pci driver

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Date:   Wed, 17 May 2023 08:36:37 -0500
From:   Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>
To:     "Mukunda,Vijendar" <vijendar.mukunda@....com>,
        Mark Brown <broonie@...nel.org>
Cc:     alsa-devel@...a-project.org, Basavaraj.Hiregoudar@....com,
        Sunil-kumar.Dommati@....com, Mastan.Katragadda@....com,
        Arungopal.kondaveeti@....com, Liam Girdwood <lgirdwood@...il.com>,
        Jaroslav Kysela <perex@...ex.cz>,
        Takashi Iwai <tiwai@...e.com>,
        Syed Saba Kareem <Syed.SabaKareem@....com>,
        Mario Limonciello <mario.limonciello@....com>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/9] ASoC: amd: ps: handle soundwire interrupts in acp pci
 driver


>>> +	if (ext_intr_stat & BIT(ACP_ERROR_IRQ_MASK)) {
>>> +		writel(BIT(ACP_ERROR_IRQ_MASK), adata->acp63_base + ACP_EXTERNAL_INTR_STAT);
>>> +		writel(0, adata->acp63_base + ACP_SW0_I2S_ERROR_REASON);
>>> +		writel(0, adata->acp63_base + ACP_SW1_I2S_ERROR_REASON);
>>> +		writel(0, adata->acp63_base + ACP_ERROR_STATUS);
>>> +		irq_flag = 1;
>> it's not clear what this does? Looks like just filtering out interrupts
>> without doing anything about the interrupt source?
> When ACP error interrupt is raised, As per our design, ACP IRQ handler will clear
> the error interrupt by clearing ACP_ERROR_IRQ bit in ACP_EXTERNAL_INTR_STAT.
> 
> To know the error source reason, we need to read the ACP_ERROR_STATUS,
> ACP_SW0_I2S_ERROR_REASON, ACP_SW1_I2S_ERROR_REASON registers.
> After reading the Error registers, we need to clear these registers.
> Currently, we haven't added read register operations for error reason registers.
> This is for debugging purpose only.
> 
> In Current context, we refer ACP_SW0_I2S_ERROR_REASON  register to know errors like
> Sound Wire Bus clash detections, Command and Response Errors, BRA mode errors,
> FIFO underflow/overflow errors detected for SoundWire Manager -0 instance.
> Similarly, ACP_SW1_I2S_ERROR_REASON register referred to know errors detected for
> SoundWire Manager instance - 1.

If you didn't add the code to deal with the errors, a comment would be
welcome to clarify that the interrupts are cleared without looking for
the root cause.

It's hard when reviewing code to understand if there's a miss or
something that's intentionally omitted or to be added later.