Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
MIME-Version: 1.0
References: <1660713867-26921-1-git-send-email-shengjiu.wang@nxp.com>
In-Reply-To: <1660713867-26921-1-git-send-email-shengjiu.wang@nxp.com>
From:   Nicolin Chen <nicoleotsuka@gmail.com>
Date:   Tue, 16 Aug 2022 23:20:56 -0700
Message-ID: <CAGoOwPT1tP-HP+0J1ddZ0Ea+67zzLzFFTeptTpNwkzxRK45b5g@mail.gmail.com>
Subject: Re: [PATCH] ASoC: fsl_sai: Remove unnecessary FIFO reset in ISR
To:     Shengjiu Wang <shengjiu.wang@nxp.com>
Cc:     Xiubo.Lee@gmail.com, festevam@gmail.com, shengjiu.wang@gmail.com,
        lgirdwood@gmail.com, broonie@kernel.org, perex@perex.cz,
        tiwai@suse.com, alsa-devel@alsa-project.org,
        linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

On Tue, Aug 16, 2022 at 10:41 PM Shengjiu Wang <shengjiu.wang@nxp.com> wrote:
>
> The FIFO reset drops the words in the FIFO, which may cause
> channel swap when SAI module is running, especially when the
> DMA speed is low. So it is not good to do FIFO reset in ISR,
> then remove the operation.

I don't recall the details of adding this many years ago, but
leaving underrun/overrun errors unhandled does not sound right
to me either. Would it result in a channel swap also? Perhaps
there needs to be a reset routine that stops and restarts the
DMA as well?