Digital Audio Multiplexer of the i.MX27 processor

Digital Audio Multiplexer of the i.MX27 processor

[Juergen Beisert]

Hi,

does anybody understand the DAM unit in the i.MX27 processor?
This routing device drivers me crazy, as I do not understand how to route 
clocks, syncs and the data signals of my internal i2s unit to the processor's 
pins.
All I can see is, when I enable the internal SSI unit in i2s mode, the DMA 
unit transfers some data into it, but the SSI unit does not shift it out. So 
everything stops, the DMA timeouts and I cannot hear anything. I can see the 
external device generates clock and frame signals, but it seems they do not 
reach the internal SSI unit.
Has anybody a working DAM configuration which uses the internal SSI#1 as an 
i2s slave, an external i2s device connected to the SSI#1 pin group of this 
processor which acts as a master (I did not find anything in the manual, how 
the relation between the internal so called port-1 to port-6 at the DAM unit 
and the 4 external SSI1...SSI4 pin groups are). Means the external i2s device 
generates the clock and frame signal and the internal SSI#1 unit in i2s mode 
should use it to send serial sound data to the external device.

Juergen
-- 
Dipl.-Ing. Juergen Beisert | http://www.pengutronix.de
 Pengutronix - Linux Solutions for Science and Industry
    Handelsregister: Amtsgericht Hildesheim, HRA 2686
         Vertretung Sued/Muenchen, Germany
   Phone: +49-8766-939 228 |  Fax: +49-5121-206917-9

Re: Digital Audio Multiplexer of the i.MX27 processor

[Peter Wurmsdobler]

Juergen,
> does anybody understand the DAM unit in the i.MX27 processor?
Not that I really understand the AUDMUX unit, but the current Freescale 
BSP (19 Dec 2007) contains an audio/alsa driver which makes use of the 
AUDMUX, or DAM, in order to route audio streams to/from the mx27's SSI1 
and SSI2 to the PMIC's SSIs. PMIC is a the power management and audio 
chip which is on the ADS board. Unfortunately I do not have the file 
with me, it is called ./sound/arm/mxc-pmic-alsa.c I believe.

I will be back in office next week, maybe we can have a chat then, if it 
is not too late.

Regards,
peter

Re: Digital Audio Multiplexer of the i.MX27 processor

[Juergen Beisert]

Peter,

On Wednesday 28 May 2008 01:03, Peter Wurmsdobler wrote:
> > does anybody understand the DAM unit in the i.MX27 processor?
>
> Not that I really understand the AUDMUX unit, but the current Freescale
> BSP (19 Dec 2007) contains an audio/alsa driver which makes use of the
> AUDMUX, or DAM, in order to route audio streams to/from the mx27's SSI1
> and SSI2 to the PMIC's SSIs. PMIC is a the power management and audio
> chip which is on the ADS board. Unfortunately I do not have the file
> with me, it is called ./sound/arm/mxc-pmic-alsa.c I believe.
>
> I will be back in office next week, maybe we can have a chat then, if it
> is not too late.

Yes, I know this file. And I'm using the code from this file to setup my DAM 
hardware. But I'm not sure if I connect the right ports in the right way to 
each other. My external PMIC is connected to the processor's SSI1_* pins. And 
it provides i2s clock and frame signal. But the internal SSI unit does not 
send any data, so I believe it does not get these signals from the PMIC.

BTW: The last instruction in the DAM code in sound/arm/mxc-pmic-alsa.c is:
  writel(AUD_MUX_CONF, IO_ADDRESS(AUDMUX_BASE_ADDR) + 0x38);
but the last valid register in the DAM unit is at AUDMUX_BASE_ADDR + 0x1C....

Juergen
-- 
Dipl.-Ing. Juergen Beisert | http://www.pengutronix.de
 Pengutronix - Linux Solutions for Science and Industry
    Handelsregister: Amtsgericht Hildesheim, HRA 2686
         Vertretung Sued/Muenchen, Germany
   Phone: +49-8766-939 228 |  Fax: +49-5121-206917-9

Re: Digital Audio Multiplexer of the i.MX27 processor

[Aditya Shankar]

Juergen,

On Tue, May 27, 2008 at 5:13 PM, Juergen Beisert <jbe@pengutronix.de> wrote:

> Hi,
>
> does anybody understand the DAM unit in the i.MX27 processor?
> This routing device drivers me crazy, as I do not understand how to route
> clocks, syncs and the data signals of my internal i2s unit to the
> processor's
> pins.


 The DAM in the Freescale chip has 3 internal ports and 3 external ports.
   The 3 internal ports connect to the on chip peripherals like the SSI. The
    external ports can be configured to connect to the off-chip codecs or
the PMIC
    The internal ports are wired to the SSI1 , SSI2 and the SAP while the
external ports
    can be configured via the IOMUX settings to connect to the PMIC or
another peripheral.



>
> All I can see is, when I enable the internal SSI unit in i2s mode, the DMA
> unit transfers some data into it, but the SSI unit does not shift it out.
> So
> everything stops, the DMA timeouts and I cannot hear anything. I can see
> the
> external device generates clock and frame signals, but it seems they do not
> reach the internal SSI unit.


 When you configure the SSI in a slave mode, the PMIC
( or your external device)will drive the FS and the clock
 required.  If you are using the file mxc-alsa-pmic.c ,
 then with SSI1 you will be mostly be connected Voice codec through
the DAM. Your configuration will
 be SSI1 -> DAM port 1 -> DAM port 4 -> Codec( ext device)
You say that the clock and frame sync from the ext. device is generated.
 SO can you check if the SSI is interrupting the DMA. If this does not
happen,
 your app can time out. Also if the DAM external port is not configured
properly
 to connect to your external device, your app would time out.
This DAM port config is done through a gpio configuration with the function
gpio_ssi_active()  in the file mx27_ads_gpio.c under arch/arm/mach-mx27
You can verify this as well.

Hope this helps.

Aditya


>
> Has anybody a working DAM configuration which uses the internal SSI#1 as an
> i2s slave, an external i2s device connected to the SSI#1 pin group of this
> processor which acts as a master (I did not find anything in the manual,
> how
> the relation between the internal so called port-1 to port-6 at the DAM
> unit
> and the 4 external SSI1...SSI4 pin groups are). Means the external i2s
> device
> generates the clock and frame signal and the internal SSI#1 unit in i2s
> mode
> should use it to send serial sound data to the external device.
>
> Juergen
> --
> Dipl.-Ing. Juergen Beisert | http://www.pengutronix.de
>  Pengutronix - Linux Solutions for Science and Industry
>     Handelsregister: Amtsgericht Hildesheim, HRA 2686
>          Vertretung Sued/Muenchen, Germany
>   Phone: +49-8766-939 228 |  Fax: +49-5121-206917-9
> _______________________________________________
> Alsa-devel mailing list
> Alsa-devel@alsa-project.org
> http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
>

Re: Digital Audio Multiplexer of the i.MX27 processor

[Juergen Beisert]

Aditya,

On Friday 30 May 2008 10:57, Aditya Shankar wrote:
> On Tue, May 27, 2008 at 5:13 PM, Juergen Beisert <jbe@pengutronix.de> wrote:
> > Hi,
> >
> > does anybody understand the DAM unit in the i.MX27 processor?
> > This routing device drivers me crazy, as I do not understand how to route
> > clocks, syncs and the data signals of my internal i2s unit to the
> > processor's
> > pins.
>
>  The DAM in the Freescale chip has 3 internal ports and 3 external ports.

Are you sure? It seems the DAM unit in the i.MX27 has two on chip ports and 
four external ports.

This I found yet (comparing mx27ads sources with mx27ads schematics):

  SSI     DAM       ext. pins
---------------------------------------
 SSI1    port_1
 SSI2    port_2
         port_3        ???
         port_4   SSI1_* pin group  <-- connected to PMIC on my board
         port_5   SSI2_* pin group
         port_6        ???

There are still the SSI3_* and SSI4_* pin groups, where I'm not sure about 
their connection to DAM unit's ports.

> > All I can see is, when I enable the internal SSI unit in i2s mode, the
> > DMA unit transfers some data into it, but the SSI unit does not shift it
> > out. So
> > everything stops, the DMA timeouts and I cannot hear anything. I can see
> > the
> > external device generates clock and frame signals, but it seems they do
> > not reach the internal SSI unit.
>
>  When you configure the SSI in a slave mode, the PMIC
> ( or your external device)will drive the FS and the clock
>  required.

SSI1 is configured as a slave, FS and clocks are inputs. Routing through the 
DAM unit seems to work now, as the SSI unit shifts out the data I'm writing 
into its FIFO.

> You say that the clock and frame sync from the ext. device is generated.
>  SO can you check if the SSI is interrupting the DMA.

This is currently my problem. The DMA does not work. If I enable the DMA it 
seems to write something into the SSI FIFO. I can check it by reading the 
FIFO counter. But at this point of time SSI1's dma_req is still disabled 
(TDMAE is 0 in register SIER)! When I enable TDMAE after enabling the DMA 
channel, next the DMA unit outputs an error: Error while transfer (DSESR bit 
of the used channel goes 1).  When I transfer the sound data in software it 
works. I'm confused.

Juergen

-- 
Dipl.-Ing. Juergen Beisert | http://www.pengutronix.de
 Pengutronix - Linux Solutions for Science and Industry
    Handelsregister: Amtsgericht Hildesheim, HRA 2686
         Vertretung Sued/Muenchen, Germany
   Phone: +49-8766-939 228 |  Fax: +49-5121-206917-9