linux-kernel - Re: [PATCH] ASoC: amd:Replacing MSI with Legacy IRQ model

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Date:   Sun, 27 Dec 2020 19:46:26 +0100
From:   Takashi Iwai <tiwai@...e.de>
To:     Jaroslav Kysela <perex@...ex.cz>
Cc:     Ravulapati Vishnu vardhan rao 
        <Vishnuvardhanrao.Ravulapati@....com>, Alexander.Deucher@....com,
        Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>, Takashi Iwai <tiwai@...e.com>,
        Akshu Agrawal <akshu.agrawal@....com>,
        Dan Carpenter <dan.carpenter@...cle.com>,
        Vijendar Mukunda <Vijendar.Mukunda@....com>,
        "moderated list:SOUND - SOC LAYER / DYNAMIC AUDIO POWER MANAGEM..." 
        <alsa-devel@...a-project.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] ASoC: amd:Replacing MSI with Legacy IRQ model

On Sun, 27 Dec 2020 19:03:28 +0100,
Jaroslav Kysela wrote:
> 
> Dne 22. 12. 20 v 12:59 Ravulapati Vishnu vardhan rao napsal(a):
> > When we try to play and capture simultaneously we see that
> > interrupts are genrated but our handler is not being acknowledged,
> > After investigating further more in detail on this issue we found
> > that IRQ delivery via MSI from the ACP IP is unreliable and so sometimes
> > interrupt generated will not be acknowledged so MSI model shouldn't be used
> > and using legacy IRQs will resolve interrupt handling issue.
> 
> What is the real culprit? It's hw bug? If not, it would be better to fix the
> PCI code or the irq handler.

I'm not surprised if it's a hardware "feature".  There are lots of
deny list and quirks about disabling MSI in HD-audio controller code,
after all.


Takashi