linux-kernel - [PATCH 3/6] ASoC: AMD: Always subtract bytescount

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Message-Id: <20180702211956.149355-3-djkurtz@chromium.org>
Date:   Mon,  2 Jul 2018 15:19:52 -0600
From:   Daniel Kurtz <djkurtz@...omium.org>
To:     unlisted-recipients:; (no To-header on input)
Cc:     Daniel Kurtz <djkurtz@...omium.org>,
        Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>,
        Jaroslav Kysela <perex@...ex.cz>,
        Takashi Iwai <tiwai@...e.com>,
        "Mukunda, Vijendar" <Vijendar.Mukunda@....com>,
        Alex Deucher <alexander.deucher@....com>,
        Akshu Agrawal <akshu.agrawal@....com>,
        Guenter Roeck <linux@...ck-us.net>,
        alsa-devel@...a-project.org (moderated list:SOUND - SOC LAYER / DYNAMIC
        AUDIO POWER MANAGEM...), linux-kernel@...r.kernel.org (open list)
Subject: [PATCH 3/6] ASoC: AMD: Always subtract bytescount

It is always correct to subtract out the starting bytescount value.  Even
in the case of 2^64 byte rollover (292 Million Years in the future
@ 48000 Hz) the math still works out.

Signed-off-by: Daniel Kurtz <djkurtz@...omium.org>
---
 sound/soc/amd/acp-pcm-dma.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/sound/soc/amd/acp-pcm-dma.c b/sound/soc/amd/acp-pcm-dma.c
index e6f85f2e5ac2a..224383fef0c3a 100644
--- a/sound/soc/amd/acp-pcm-dma.c
+++ b/sound/soc/amd/acp-pcm-dma.c
@@ -995,8 +995,7 @@ static snd_pcm_uframes_t acp_dma_pointer(struct snd_pcm_substream *substream)
 	buffersize = frames_to_bytes(runtime, runtime->buffer_size);
 	bytescount = acp_get_byte_count(rtd);
 
-	if (bytescount > rtd->bytescount)
-		bytescount -= rtd->bytescount;
+	bytescount -= rtd->bytescount;
 	pos = do_div(bytescount, buffersize);
 	return bytes_to_frames(runtime, pos);
 }
-- 
2.18.0.399.gad0ab374a1-goog