The feedback endponit doesn't work with Evaluation-Driver-for-Windows_5_72 ?

[Henry]

Update:
In the xmos_usb_audio software, the USB input stream packets size is already related to SOF speed.
I said that "USB_CHAN_IN data size is not associated with the actual host rate" is incorrect, sorry!

Testing at 48KHz, 24bit, 2ch, by the Wirkshark tool, I can see that the USB input stream packet size dynamically adjusts between 6 and 5.
And the size of the USB output stream is also dynamically adjusted between 6 and 5. It seems that implicit feedback is works.

However the random "blanks space" on the DAC line still present.

[lmariotti]

Hi Ross,

as suggested I've checked for zero-count on mclk as

Code: Select all

/* Get MCLK count */
asm volatile(" getts %0, res[%1]" : "=r" (u_tmp) : "r" (p_off_mclk));
if(u_tmp == 0)
	count_zero_clk++;

in fact count_zero_clk is > 0 after a few time of streaming, would this suggest some kind of hardware issue on MCLK side?

[Ross]

yes, that is a bad sign. Port isn't getting a mclk signal or the clock hasn't been started.

I just noticed you have a slightly odd hardware arrangement, I think its worth checking that the clockblock is indeed started, otherwise the port counter will remain at zero

You will want to make sure that start_clock(clk_name); is called.

[lmariotti]

Hi Ross,

I'm using sw_usb_audio v9.1.0 leaving untouched usb clocks.
I've AUDIO_IO_TILE != XUD_TILE so from lib_xua\src\core\main.xc seems that clock block is started

Code: Select all

on tile[AUDIO_IO_TILE] : clock clk_audio_mclk               = CLKBLK_MCLK;       /* Master clock */

#if (AUDIO_IO_TILE != XUD_TILE) && XUA_USB_EN
/* Separate clock/port for USB feedback calculation */
on tile[XUD_TILE] : clock clk_audio_mclk_usb                = CLKBLK_MCLK;       /* Master clock */
#endif

...

                /* Attach mclk count port to mclk clock-block (for feedback) */
                //set_port_clock(p_for_mclk_count, clk_audio_mclk);
#if(AUDIO_IO_TILE != XUD_TILE)
                set_clock_src(clk_audio_mclk_usb, p_mclk_in_usb);
                set_port_clock(p_for_mclk_count, clk_audio_mclk_usb);
                start_clock(clk_audio_mclk_usb);
#else
                /* Clock port from same clock-block as I2S */
                /* TODO remove asm() */
                asm("ldw %0, dp[clk_audio_mclk]":"=r"(x));
                asm("setclk res[%0], %1"::"r"(p_for_mclk_count), "r"(x));
#endif

Anyway that happend only using "Evaluation-Driver-for-Windows", without drivers or with an Android device the problem doesn't occour, could this still be a hardware issue?