Re: [PATCH v2] ASoC: codecs: add uspport for the TI SRC4392 codec

[Matt Flax <flatmax@flatmax.com>]

On 17/8/22 04:00, Nathan Chancellor wrote:

>>     265			/* set the PLL for the digital receiver */
>>     266			switch (src4xxx->mclk_hz) {
>>     267			case 24576000:
>>     268				pj = 0x22;
>>     269				jd = 0x00;
>>     270				d = 0x00;
>>     271				break;
>>     272			case 22579200:
>>     273				pj = 0x22;
>>     274				jd = 0x1b;
>>     275				d = 0xa3;
>>     276				break;
>>   > 277			default:
>>     278				/* don't error out here,
>>     279				 * other parts of the chip are still functional
>>     280				 */
>>     281				dev_info(component->dev,
>>     282					"Couldn't set the RCV PLL as this master clock rate is unknown\n");
> In the final commit, there is a 'break' here. Should it be a 'return 0'
> instead? Or should there be a different fix for these warnings?

The data sheet for the src4392 doesn't list defaults for these registers 
(loaded with pj, jd and d). The actual state of these registers is not 
known until we load them with something, arbitrary or not.

	{  SRC4XXX_RCV_PLL_0F,		0x00  },  /* not spec. in the datasheet */
	{  SRC4XXX_RCV_PLL_10,		0xff  },  /* not spec. in the datasheet */
	{  SRC4XXX_RCV_PLL_11,		0xff  },  /* not spec. in the datasheet */

The state of DIR PLL registers aren't important if the user doesn't 
specify a known mclk frequency.  The implication is that the DIR will 
not function, however that is already implied by the user lacking to 
specify a known mclk frequency.

The other functions on the chip (port A/B I2S, SRC, DIT, etc) will 
behave as per usual, only the DIR will be dysfunctional.


>>     283			}
>>     284			ret = regmap_write(src4xxx->regmap, SRC4XXX_RCV_PLL_0F, pj);
>>     285			if (ret < 0)
>>     286				dev_err(component->dev,
>>     287					"Failed to update PLL register 0x%x\n",
>>     288					SRC4XXX_RCV_PLL_0F);
>>   > 289			ret = regmap_write(src4xxx->regmap, SRC4XXX_RCV_PLL_10, jd);
>>     290			if (ret < 0)
>>     291				dev_err(component->dev,
>>     292					"Failed to update PLL register 0x%x\n",
>>     293					SRC4XXX_RCV_PLL_10);
>>   > 294			ret = regmap_write(src4xxx->regmap, SRC4XXX_RCV_PLL_11, d);
>>     295			if (ret < 0)
>>     296				dev_err(component->dev,
>>     297					"Failed to update PLL register 0x%x\n",
>>     298					SRC4XXX_RCV_PLL_11);
>>     
> Cheers,
> Nathan