Re: [PATCH] drm/bridge: dw-hdmi-qp: Return -EOPNOTSUPP in HDMI audio functions

["Diederik de Haas" <diederik@cknow-tech.com>]

Hi Detlev,

On Tue May 19, 2026 at 8:00 PM CEST, Detlev Casanova wrote:
> -EOPNOTSUPP is not logged as an error by the ASoC subsystem, but -ENODEV
> is.
> It also better represents the situation: The operation is currently not
> supported (because clocks are not enabled and tmds_char_rate is
> unavailable), but the hardware is present.
>
> Using -EOPNOTSUPP in the audio_prepare callback removes possible repeated
> warning log lines when HDMI is not connected.

IME/IMO that's a bit of an understatement as I got 10/100/1000s of these:

  hdmi-audio-codec hdmi-audio-codec.6.auto: ASoC error (-19): at snd_soc_dai_prepare() on i2s-hifi

In my test without this patch, I booted up my SBCs, logged in quickly and
still got 60/120/270 of these errors in dmesg ... and I wasn't actually 
using HDMI at that time. Previously, more then once did it completely
fill the dmesg buffer, removing/hiding the things I actually wanted to see.

> Returning -EOPNOTSUPP in the audio_enable callback is also needed as it
> avoids logging 0-valued ELD errors.

I've seen those too, multiple times, although it didn't annoy me as much
as the above one ... due to the (much) lower frequency. So

1) Thanks a LOT for this patch :-D
2) Feel free to include my

Tested-by: Diederik de Haas <diederik@cknow-tech.com>  # Rock 5B, NanoPC-T6 LTS & Plus

Cheers,
  Diederik

> When tmds_char_rate is available, the clocks are enabled and the
> functions will keep returning 0 as before.
>
> Signed-off-by: Detlev Casanova <detlev.casanova@collabora.com>
> ---
>  drivers/gpu/drm/bridge/synopsys/dw-hdmi-qp.c | 8 +++++---
>  1 file changed, 5 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/bridge/synopsys/dw-hdmi-qp.c b/drivers/gpu/drm/bridge/synopsys/dw-hdmi-qp.c
> index d649a1cf07f5..270c8c47d853 100644
> --- a/drivers/gpu/drm/bridge/synopsys/dw-hdmi-qp.c
> +++ b/drivers/gpu/drm/bridge/synopsys/dw-hdmi-qp.c
> @@ -469,8 +469,10 @@ static int dw_hdmi_qp_audio_enable(struct drm_bridge *bridge,
>  {
>  	struct dw_hdmi_qp *hdmi = dw_hdmi_qp_from_bridge(bridge);
>  
> -	if (hdmi->tmds_char_rate)
> -		dw_hdmi_qp_mod(hdmi, 0, AVP_DATAPATH_PACKET_AUDIO_SWDISABLE, GLOBAL_SWDISABLE);
> +	if (!hdmi->tmds_char_rate)
> +		return -EOPNOTSUPP;
> +
> +	dw_hdmi_qp_mod(hdmi, 0, AVP_DATAPATH_PACKET_AUDIO_SWDISABLE, GLOBAL_SWDISABLE);
>  
>  	return 0;
>  }
> @@ -484,7 +486,7 @@ static int dw_hdmi_qp_audio_prepare(struct drm_bridge *bridge,
>  	bool ref2stream = false;
>  
>  	if (!hdmi->tmds_char_rate)
> -		return -ENODEV;
> +		return -EOPNOTSUPP;
>  
>  	if (fmt->bit_clk_provider | fmt->frame_clk_provider) {
>  		dev_err(hdmi->dev, "unsupported clock settings\n");
>
> ---
> base-commit: 1a2ab0feaa23147e347b4d4cb79cb3fc392118eb
> change-id: 20260519-fix-hdmi-audio-warnings-139062ec00b9
>
> Best regards,
> --  
> Detlev Casanova <detlev.casanova@collabora.com>