ASOC: Best way to get private data from machine driver to the other drivers?

ASOC: Best way to get private data from machine driver to the other drivers?

[Timur Tabi]

I'm writing an ASOC driver.  When my machine driver loads, it determines some 
hardware information for the DMA controllers, some other hardware information 
for the I2S controller, and even more information for the codec.

I want to be able to pass all this information to each of the three other 
drivers.  Unfortunately, it doesn't appear that I have enough "private_data" 
pointers available to me.

The current ASOC drivers all use statically defined global structures and 
indexes into arrays of these structures to identify individual devices, such 
associating I2S controller #2 with DMA channels 3 and 4.  On PowerPC, this 
doesn't work.  The actual hardware configuration is determined at runtime (see 
arch/powerpc/boot/dts/), and so the machine driver needs to collect all the 
information and make all the device-to-device associations.

For example, the PCM driver has an open function:

static struct snd_pcm_ops fsl_dma_ops = {
	.open           = fsl_dma_open,
	...

static int fsl_dma_open(struct snd_pcm_substream *substream)
{
	...

What I would like is for fsl_dma_open() to be able to obtain pointers to the 
DMA controller's registers (there are two controllers with 4 channels each) by 
looking inside 'substream'.  How can I do that?

-- 
Timur Tabi
Linux Kernel Developer @ Freescale

Re: ASOC: Best way to get private data from machine driver to the other drivers?

[Liam Girdwood]

On Fri, 2007-09-28 at 16:14 -0500, Timur Tabi wrote:
> I'm writing an ASOC driver.  When my machine driver loads, it determines some 
> hardware information for the DMA controllers, some other hardware information 
> for the I2S controller, and even more information for the codec.
> 
> I want to be able to pass all this information to each of the three other 
> drivers.  Unfortunately, it doesn't appear that I have enough "private_data" 
> pointers available to me.
> 
> The current ASOC drivers all use statically defined global structures and 
> indexes into arrays of these structures to identify individual devices, such 
> associating I2S controller #2 with DMA channels 3 and 4.  On PowerPC, this 
> doesn't work.  The actual hardware configuration is determined at runtime (see 
> arch/powerpc/boot/dts/), and so the machine driver needs to collect all the 
> information and make all the device-to-device associations.
> 
> For example, the PCM driver has an open function:
> 
> static struct snd_pcm_ops fsl_dma_ops = {
> 	.open           = fsl_dma_open,
> 	...
> 
> static int fsl_dma_open(struct snd_pcm_substream *substream)
> {
> 	...
> 
> What I would like is for fsl_dma_open() to be able to obtain pointers to the 
> DMA controller's registers (there are two controllers with 4 channels each) by 
> looking inside 'substream'.  How can I do that?
> 

I think we have addressed this now in ASoC V2. Every component driver
now registers as a standard Linux device driver. It would probably be
possible to read the dts configuration at probe() and then configure the
driver with the correct DMA pointers before calling driver_register().

http://opensource.wolfsonmicro.com/cgi-bin/gitweb/gitweb.cgi?p=linux-2.6-asoc;a=shortlog;h=asoc-v2-dev

Could you have a look at the V2 i.mx31 SSI driver and let me know if we
need further changes for better dts support.

Thanks

Liam

Re: ASOC: Best way to get private data from machine driver to the other drivers?

[Timur Tabi]

Liam Girdwood wrote:

> Could you have a look at the V2 i.mx31 SSI driver and let me know if we
> need further changes for better dts support.

I'll do that.  However, I still have the same problem - without a git-http 
interface, my ability to "work with" that repository is limited.  Can you 
create a repo on kernel.org?  I have git better access to that site.

-- 
Timur Tabi
Linux Kernel Developer @ Freescale

Re: ASOC: Best way to get private data from machine driver to the other drivers?

[Liam Girdwood]

On Mon, 2007-10-01 at 15:10 -0500, Timur Tabi wrote:
> Liam Girdwood wrote:
> 
> > Could you have a look at the V2 i.mx31 SSI driver and let me know if we
> > need further changes for better dts support.
> 
> I'll do that.  However, I still have the same problem - without a git-http 
> interface, my ability to "work with" that repository is limited.  Can you 
> create a repo on kernel.org?  I have git better access to that site.
> 

Do you know who would be the best person to ask for this ?

If it's ok with the kernel.org folks I can do this.

Liam

Re: ASOC: Best way to get private data from machine driver to the other drivers?

[Timur Tabi]

Liam Girdwood wrote:

> Do you know who would be the best person to ask for this ?
> 
> If it's ok with the kernel.org folks I can do this.

http://kernel.org/faq/#account

-- 
Timur Tabi
Linux Kernel Developer @ Freescale

Re: ASOC: Best way to get private data from machine driver to the other drivers?

[Timur Tabi]

Liam Girdwood wrote:
> On Mon, 2007-10-01 at 15:10 -0500, Timur Tabi wrote:
>> Liam Girdwood wrote:
>>
>>> Could you have a look at the V2 i.mx31 SSI driver and let me know if we
>>> need further changes for better dts support.
>> I'll do that.  However, I still have the same problem - without a git-http 
>> interface, my ability to "work with" that repository is limited.  Can you 
>> create a repo on kernel.org?  I have git better access to that site.
>>
> 
> Do you know who would be the best person to ask for this ?

I take it that enabling git-http access is not an option?  Normally, that 
would be easier than getting an account on kernel.org.

-- 
Timur Tabi
Linux Kernel Developer @ Freescale

Re: ASOC: Best way to get private data from machine driver to the other drivers?

[Timur Tabi]

Liam Girdwood wrote:

> Could you have a look at the V2 i.mx31 SSI driver and let me know if we
> need further changes for better dts support.

I'm trying to port the CS4270 codec driver (it's easier) to ASOC v2, and I see 
that you don't have snd_pcm_rate_to_rate_bit().  Where did it go?

-- 
Timur Tabi
Linux Kernel Developer @ Freescale

Re: ASOC: Best way to get private data from machine driver to the other drivers?

[Liam Girdwood]

On Mon, 2007-10-01 at 16:49 -0500, Timur Tabi wrote:
> Liam Girdwood wrote:
> 
> > Could you have a look at the V2 i.mx31 SSI driver and let me know if we
> > need further changes for better dts support.
> 
> I'm trying to port the CS4270 codec driver (it's easier) to ASOC v2, and I see 
> that you don't have snd_pcm_rate_to_rate_bit().  Where did it go?
> 

We never had a snd_pcm_rate_to_rate_bit() in the ASoC code, perhaps you
mean something else ?

Liam

Re: ASOC: Best way to get private data from machine driver to the other drivers?

[Timur Tabi]

Liam Girdwood wrote:
> On Mon, 2007-10-01 at 16:49 -0500, Timur Tabi wrote:
>> Liam Girdwood wrote:
>>
>>> Could you have a look at the V2 i.mx31 SSI driver and let me know if we
>>> need further changes for better dts support.
>> I'm trying to port the CS4270 codec driver (it's easier) to ASOC v2, and I see 
>> that you don't have snd_pcm_rate_to_rate_bit().  Where did it go?
>>
> 
> We never had a snd_pcm_rate_to_rate_bit() in the ASoC code, perhaps you
> mean something else ?

In may not be part of ASoC, but it's part of ALSA, and I need it.  It's not 
just in your repository.

sound/core/pcm_misc.c

/**
  * snd_pcm_rate_to_rate_bit - converts sample rate to SNDRV_PCM_RATE_xxx bit
  * @rate: the sample rate to convert
  *
  * Returns the SNDRV_PCM_RATE_xxx flag that corresponds to the given rate, or
  * SNDRV_PCM_RATE_KNOT for an unknown rate.
  */
unsigned int snd_pcm_rate_to_rate_bit(unsigned int rate)
{
	unsigned int i;

	for (i = 0; i < snd_pcm_known_rates.count; i++)
		if (snd_pcm_known_rates.list[i] == rate)
			return 1u << i;
	return SNDRV_PCM_RATE_KNOT;
}
EXPORT_SYMBOL(snd_pcm_rate_to_rate_bit);

-- 
Timur Tabi
Linux Kernel Developer @ Freescale