[RESEND] drm/i2c: tda998x: Reset the I2S_FORMAT (Page0, Reg 0xfc) to it's default

[Russell King - ARM Linux admin]

On Fri, Feb 22, 2019 at 03:47:14PM +0200, Peter Ujfalusi wrote:
> Hi,
> 
> the original version was sent 14.04.2018:
> https://patchwork.kernel.org/patch/10344403/
> 
> Changes since then:
> - rebased on currentl drm/next
> 
> The reset value of the register is 0, the soft reset does not reset this
> register and if other kernel changed this the audio is going to be
> distorted.
> 
> It was observed when - accidentally - booted the kernel from eMMC on BBB
> which is 3.8.13-bone79 and it sets this register to 0x0a. After reboot and
> tda998x_reset() it remains 0x0a.

Have you checked whether the input I2S stream is Philips or Left
Justified?  This is controlled by the LSB two bits.

It appears that 3.8.13-bone79 configures the TDA998x for left-
justified, whereas re-setting these two bits to zero will configure
it for Philips.

Bits 3:2 control the data size, but I have no information what their
values correspond to.

Can we nail down what is required for BBB and what it doesn't care
about - and I think we should implement at least setting the I2S
register format from the hdmi_codec_daifmt data.

It would also be good to know what Fs value(s) BBB uses, and what
sample sizes you have tested.

> 
> Signed-off-by: Peter Ujfalusi <peter.ujfalusi at ti.com>
> ---
>  drivers/gpu/drm/i2c/tda998x_drv.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i2c/tda998x_drv.c b/drivers/gpu/drm/i2c/tda998x_drv.c
> index 7f34601bb515..72f93802d209 100644
> --- a/drivers/gpu/drm/i2c/tda998x_drv.c
> +++ b/drivers/gpu/drm/i2c/tda998x_drv.c
> @@ -722,6 +722,9 @@ tda998x_reset(struct tda998x_priv *priv)
>  
>  	/* Write the default value MUX register */
>  	reg_write(priv, REG_MUX_VP_VIP_OUT, 0x24);
> +
> +	/* Write the default to I2S_FORMAT register */
> +	reg_write(priv, REG_I2S_FORMAT,   0x00);
>  }
>  
>  /*
> -- 
> Peter
> 
> Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki.
> Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki
> 
> 

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