[alsa-devel] Please help in adding ams-delta support to ASoC

[Janusz Krzysztofik]

Jarkko Nikula wrote:
> On Sat, 6 Jun 2009 00:28:00 +0200
> Janusz Krzysztofik <jkrzyszt at tis.icnet.pl> wrote:
>> My last idea was to create a generic test driver that would not use
>> any external clocks, ie configured with OMAP_MCBSP_SYSCLK_CLK and
>> SND_SOC_DAIFMT_CBS_CFS, right? That way, it should just work without
>> any hardware support except for mcbsp and maybe we could then
>> definitelly verify if current mcbsp and dma code works on omap1510 or
>> not.
>>
> This could be a bit risky and can damage your HW since both OMAP and
> codec are then driving the bit-clock and FS signals but you could try
> to configure McBSP as a master and use the internal clock source as its
> input.

I found that in OMAP5910, CLKR and FSR signals are not connected to any 
pins, so I can safely set them as output. To make use of this feature, I 
have modified sound/soc/omap/omap-mcbsp.c slightly:

diff -Npru linux-2.6.29/sound/soc/omap/omap-msbsp.c.orig 
linux-2.6.29/sound/soc/omap/omap-mcbsp.c
--- linux-2.6.29/sound/soc/omap/omap-mcbsp.c.orig       2009-06-09 
02:16:32.000000000 +0200
+++ linux-2.6.29/sound/soc/omap/omap-mcbsp.c    2009-06-09 
02:25:50.000000000 +0200
@@ -341,8 +341,8 @@ static int omap_mcbsp_dai_set_dai_fmt(st
         switch (fmt & SND_SOC_DAIFMT_MASTER_MASK) {
         case SND_SOC_DAIFMT_CBS_CFS:
                 /* McBSP master. Set FS and bit clocks as outputs */
-               regs->pcr0      |= FSXM | FSRM |
-                                  CLKXM | CLKRM;
+               regs->pcr0      |= FSRM |
+                                  CLKRM;
                 /* Sample rate generator drives the FS */
                 regs->srgr2     |= FSGM;
                 break;

> Basically it goes with current driver by passing SND_SOC_DAIFMT_CBS_CFS
> to snd_soc_dai_set_fmt(cpu_dai, ...) and by setting SRG source clock
> and divider:
> 
> snd_soc_dai_set_sysclk(cpu_dai, OMAP_MCBSP_SYSCLK_CLK, ...);
> snd_soc_dai_set_clkdiv(cpu_dai, OMAP_MCBSP_CLKGDV, divider);

So I restored all that 12MHz mclk stuff that I had already removed as 
redundant, then set up the following in oder to get internally generated 
~256kHz CLKR and ~8kHz FSR:

+       /* Set cpu DAI configuration */
+       err = snd_soc_dai_set_fmt(cpu_dai,
+                                 SND_SOC_DAIFMT_I2S |
+                                 SND_SOC_DAIFMT_IB_IF |
+                                 SND_SOC_DAIFMT_CBS_CFS);
+       if (err < 0) {
+               printk(KERN_ERR "can't set cpu DAI configuration\n");
+               return err;
+       }
+
+       /* Set cpu DAI master clock source */
+       err =
+           snd_soc_dai_set_sysclk(cpu_dai, OMAP_MCBSP_SYSCLK_CLK,
+                                       0, SND_SOC_CLOCK_IN);
+
+       if (err < 0) {
+               printk(KERN_ERR "can't set cpu DAI clock source\n");
+               return err;
+       }
+
+       /* Set cpu DAI master clock divisor */
+       err =
+           snd_soc_dai_set_clkdiv(cpu_dai, OMAP_MCBSP_CLKGDV, 47);
+
+       if (err < 0) {
+               printk(KERN_ERR "can't set cpu DAI clock divisor\n");
+               return err;
+       }

Tried with both arecord and </dev/dsp, it looks like the problem still 
persists, even with mcbsp internally generated clocking. I have also 
tested a similiar mcbsp configuration with old driver for reference - it 
works.

Importand or not, I have to fine down my provious reports on what works 
and what does not:

- original patch applied with other ams-delta related patches
   on linux-omap-2.6.16, as it was designed for:
   - playback: works, with both aplay and >/dev/dsp,
   - capture: works with </dev/dsp, gives null output with arecord

- original patch ported to the last l-o commit supporting omap-alsa:
   - playback: works as before,
   - capture: both </dev/dsp and arecord give null output,
     but DMA interrupts still work.

- new driver on l-o: total hangup

- new driver on mainline 2.6.30-rc5: no DMA interrupts.

Thanks,
Janusz
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