This patch solve below report from Guennadi

> +static struct snd_soc_dai_driver sh_hdmi_dai = {
> +	.name = "sh_mobile_hdmi-hifi",
> +	.playback = {
> +		.stream_name = "Playback",
> +		.channels_min = 1,

Can it actually do mono? Maybe at probe time you could look at audio flags
from your previous patch and, e.g., for SPDIF set channels_min to 2?

> +		.channels_max = 2,

That's the "smallest max," yes. With some other interfaces (I2S, DSD) it
can support up to 8 channels...

> +		.rates = SNDRV_PCM_RATE_8000_48000,

Hm, in the datasheet I see supported frequencies 32kHz to 192kHz. And if
you promise support for multiple frequencies, don't you want to implement
.hw_params? Besides, not all of these frequencies will be available,
depending on your supplied clock and your willingness to implement
downsampling.
Reported-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Reviewed-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Acked-by: Liam Girdwood <lrg@slimlogic.co.uk>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>