Re: [alsa-devel] [PATCH 2/4] ASoC: fsi: Add FIFO size calculate

On Wed, 2010-03-17 at 14:26 +0900, Kuninori Morimoto wrote:

Signed-off-by: Kuninori Morimoto morimoto.kuninori@renesas.com

sound/soc/sh/fsi.c | 48 +++++++++++++++++++++++------------------------- 1 files changed, 23 insertions(+), 25 deletions(-)

diff --git a/sound/soc/sh/fsi.c b/sound/soc/sh/fsi.c index db91349..cc41bae 100644 --- a/sound/soc/sh/fsi.c +++ b/sound/soc/sh/fsi.c @@ -46,8 +46,9 @@ #define MUTE 0x020C #define CLK_RST 0x0210 #define SOFT_RST 0x0214 +#define FIFO_SZ 0x0218 #define MREG_START INT_ST -#define MREG_END SOFT_RST +#define MREG_END FIFO_SZ

/* DO_FMT */ /* DI_FMT */ @@ -85,6 +86,11 @@ #define IR (1 << 4) /* Interrupt Reset */ #define FSISR (1 << 0) /* Software Reset */

+/* FIFO_SZ */ +#define OUT_SZ_MASK 0x7 +#define BO_SZ_SHIFT 8 +#define AO_SZ_SHIFT 0

#define FSI_RATES SNDRV_PCM_RATE_8000_96000

#define FSI_FMTS (SNDRV_PCM_FMTBIT_S24_LE | SNDRV_PCM_FMTBIT_S16_LE) @@ -590,11 +596,12 @@ static int fsi_dai_startup(struct snd_pcm_substream *substream, struct snd_soc_dai *dai) { struct fsi_priv *fsi = fsi_get_priv(substream);

• struct fsi_master *master = fsi_get_master(fsi); const char *msg; u32 flags = fsi_get_info_flags(fsi); u32 fmt; u32 reg;

• u32 data;

• u32 data, i; int is_play = (substream->stream == SNDRV_PCM_STREAM_PLAYBACK); int is_master; int ret = 0;

@@ -668,31 +675,22 @@ static int fsi_dai_startup(struct snd_pcm_substream *substream, dev_err(dai->dev, "unknown format.\n"); return -EINVAL; }

• switch (fsi->chan) {
• case 1:

• fsi->fifo_max = 256;
  

• break;
  

• case 2:

• fsi->fifo_max = 128;
  

• break;
  

• case 3:
• case 4:

• fsi->fifo_max = 64;
  

• break;
  

• case 5:
• case 6:
• case 7:
• case 8:

• fsi->fifo_max = 32;
  

• break;
  

• default:

• dev_err(dai->dev, "channel size error.\n");
  

• return -EINVAL;
  

• }
• fsi_reg_write(fsi, reg, data);

• /* calculate FIFO size */
• data = fsi_master_read(master, FIFO_SZ);
• data >>= fsi_is_port_a(fsi) ? AO_SZ_SHIFT : BO_SZ_SHIFT;
• data &= OUT_SZ_MASK;
• fsi->fifo_max = 256;
• for (i = 0; i < data; i++)

• fsi->fifo_max <<= 1;
  

You don't really need the for loop here if you calculate the shift size and perform the shift in 1 operation. e.g.

fsi->fifo_max <<= data;

• dev_dbg(dai->dev, "fifo = %d words\n", fsi->fifo_max);
• for (i = 1; i < fsi->chan; i *= 2)

• if (fsi->chan > i)
  

• 	fsi->fifo_max >>= 1;
  

Is the if really needed here. You may also want to calculate the shift size rather than looping too.

Thanks

Liam