We want to allocate enough space for CS5535AUDIO_MAX_DESCRIPTORS + 1 elements and we also want the size to rounded up to PAGE_SIZE. The "+ 1" is because we don't use the zeroeth element.
CS5535AUDIO_MAX_DESCRIPTORS is 128. Each element is 8 bytes. So it should be "(128 + 1) * 8 = 1032" but rounded up that becomes 4096. In the original code, it did the "+ 1" after rounding up so so it allocated 4097 bytes. The DMA API will probably round this up to two pages.
Fixes: 9b4ffa48ae85 ("[ALSA] Add support for the CS5535 Audio device") Signed-off-by: Dan Carpenter dan.carpenter@oracle.com --- sound/pci/cs5535audio/cs5535audio_pcm.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/sound/pci/cs5535audio/cs5535audio_pcm.c b/sound/pci/cs5535audio/cs5535audio_pcm.c index 4032b89b1fc1d..f6324636b355f 100644 --- a/sound/pci/cs5535audio/cs5535audio_pcm.c +++ b/sound/pci/cs5535audio/cs5535audio_pcm.c @@ -100,7 +100,7 @@ static int snd_cs5535audio_playback_close(struct snd_pcm_substream *substream) }
#define CS5535AUDIO_DESC_LIST_SIZE \ - PAGE_ALIGN(CS5535AUDIO_MAX_DESCRIPTORS * sizeof(struct cs5535audio_dma_desc)) + PAGE_ALIGN((CS5535AUDIO_MAX_DESCRIPTORS + 1) * sizeof(struct cs5535audio_dma_desc))
static int cs5535audio_build_dma_packets(struct cs5535audio *cs5535au, struct cs5535audio_dma *dma, @@ -118,7 +118,7 @@ static int cs5535audio_build_dma_packets(struct cs5535audio *cs5535au, if (dma->desc_buf.area == NULL) { if (snd_dma_alloc_pages(SNDRV_DMA_TYPE_DEV, &cs5535au->pci->dev, - CS5535AUDIO_DESC_LIST_SIZE+1, + CS5535AUDIO_DESC_LIST_SIZE, &dma->desc_buf) < 0) return -ENOMEM; dma->period_bytes = dma->periods = 0;