[alsa-devel] at91 SoC Modifications

[Frank Mandarino]

Paul Kavan wrote:
> Hello all:
> 
> I have been struggling to determine why the sync line (TF0) behaves so
> strangely when in capture mode yet acts fine in playback mode. So far, no
> real clues. However, I do have a few questions. I have DATADEF set for TD0
> set to 1. However, at the end of a playback it pulls to zero. Any clue why
> this might be happening?

Perhaps it is due to the SSC being reset when the playback channel is
closed?

> Also, in the machine code, I set up some test code to printk back the gpio
> registers:
> 
> the code for the gpio is given as
> 
> #define AT91_PIO_TK0    (1 << (AT91_PIN_PB16 - PIN_BASE) % 32)
> #define AT91_PIO_TF0    (1 << (AT91_PIN_PB17 - PIN_BASE) % 32)
> #define AT91_PIO_TD0    (1 << (AT91_PIN_PB18 - PIN_BASE) % 32)
> #define AT91_PIO_RD0    (1 << (AT91_PIN_PB19 - PIN_BASE) % 32)
> #define AT91_PIO_RK0    (1 << (AT91_PIN_PB20 - PIN_BASE) % 32)
> #define AT91_PIO_RF0    (1 << (AT91_PIN_PB21 - PIN_BASE) % 32)
> .
> .
> .
>    ssc_pio_lines = AT91_PIO_TF0 | AT91_PIO_TK0 | AT91_PIO_TD0
>            | AT91_PIO_RD0 /*| AT91_PIO_RK0 | AT91_PIO_RF0*/ ;
> 
>        printk("SSC PIO LINES is 0x%x\n",ssc_pio_lines);
>    /* Reset all PIO registers and assign lines to peripheral A */
>     at91_sys_write(AT91_PIOB + PIO_PDR,  ssc_pio_lines);
>     at91_sys_write(AT91_PIOB + PIO_ODR,  ssc_pio_lines);
>     at91_sys_write(AT91_PIOB + PIO_IFDR, ssc_pio_lines);
>     at91_sys_write(AT91_PIOB + PIO_CODR, ssc_pio_lines);
>     at91_sys_write(AT91_PIOB + PIO_IDR,  ssc_pio_lines);
>     at91_sys_write(AT91_PIOB + PIO_MDDR, ssc_pio_lines);
>     at91_sys_write(AT91_PIOB + PIO_PUDR, ssc_pio_lines);
>     at91_sys_write(AT91_PIOB + PIO_ASR,  ssc_pio_lines);
>     at91_sys_write(AT91_PIOB + PIO_OWDR, ssc_pio_lines);
> 
>        /*TEST CODE*/
>        printk("PIOB-PDR is set to %d\n",at91_sys_read(AT91_PIOB +
> PIO_PDR));
>     printk("PIOB-ODR is set to %d\n",at91_sys_read(AT91_PIOB + PIO_ODR));
>     printk("PIOB-IFDR is set to %d\n",at91_sys_read(AT91_PIOB + PIO_IFDR));
>     printk("PIOB-CODR is set to %d\n",at91_sys_read(AT91_PIOB + PIO_CODR));
>     printk("PIOB-IRD is set to %d\n",at91_sys_read(AT91_PIOB + PIO_IDR));
>     printk("PIOB-MDDR is set to %d\n",at91_sys_read(AT91_PIOB + PIO_MDDR));
>     printk("PIOB-PUDR is set to %d\n",at91_sys_read(AT91_PIOB + PIO_PUDR));
>     printk("PIOB-ASR is set to %d\n",at91_sys_read(AT91_PIOB + PIO_ASR));
>     printk("PIOB-OWDR is set to %d\n",at91_sys_read(AT91_PIOB + PIO_OWDR));
>        /*END OF TEST CODE*/
> 
> 
> and the result at boot is:
> 
> AT91SAM9260EK W6811 Driver <1>
> w6811: W6811 PCM SoC Audio 0.1
> asoc: W6811 <-> at91-ssc0 mapping ok
> SSC PIO LINES is 0xf0000
> PIOB-PDR is set to 0
> PIOB-ODR is set to 0
> PIOB-IFDR is set to 0
> PIOB-CODR is set to 0
> PIOB-IRD is set to 0
> PIOB-MDDR is set to 0
> PIOB-PUDR is set to 0
> PIOB-ASR is set to 0
> PIOB-OWDR is set to 0
> 
> ...why are all the registers set to 0?

These registers are all write-only registers.  You have to read their
corresponding status registers to see what values are set.

../fam
-- 
Frank Mandarino                                fmandarino(a)endrelia.com
Endrelia Technologies Inc.
Toronto, Ontario, Canada