linux-kernel - Re: [PATCH v2] regmap-irq: Use regmap_irq_update_bits instead of regmap

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Message-ID: <c055e4e8-fd11-49e9-c7a9-bf2f1ec9de36@quicinc.com>
Date:   Wed, 9 Feb 2022 14:11:13 +0530
From:   Prasad Kumpatla <quic_pkumpatl@...cinc.com>
To:     Marek Szyprowski <m.szyprowski@...sung.com>,
        Mark Brown <broonie@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        <linux-kernel@...r.kernel.org>,
        Krzysztof Kozlowski <krzk@...nel.org>,
        'Linux Samsung SOC' <linux-samsung-soc@...r.kernel.org>
Subject: Re: [PATCH v2] regmap-irq: Use regmap_irq_update_bits instead of
 regmap_write


On 2/8/2022 5:59 PM, Marek Szyprowski wrote:

> There is something wrong with this patch. Since it landed in linux-next
> (20220204) I get an interrupt storm on two of my test devices:
>
> 1. ARM 32bit Exynos4412-based Trats2 ("wm8994-codec wm8994-codec: FIFO
> error" message)
>
> 2. ARM 64bit Exynos5433-based TM2e ("arizona spi1.0: Mixer dropped
> sample" message)
>
> Definitely the interrupts are not acknowledged properly. Once I find
> some spare time, I will check it further which regmap configuration
> triggers the issue, but it is definitely related to this patch.
> Reverting it on top of current linux-next fixes the issue.

Change is needed to handle the interrupt ack properly to clear the ack.

I observed that the regmap_irq_update_bits() writes the register only if 
it finds a difference b/w existing reg value to update reg value.

This may be causing the interrupt storm issue mentioned above.

Setting the mask_writeonly flag to 1, to force write the register may 
resolve the interrupt storm issue.

--Prasad