On Wed, 09 Nov 2016, [email protected] wrote:
> From: Libin Yang <[email protected]>
>
> This issue is caused by:
> 6014ac12: drm/i915/audio: set proper N/M in modeset
>
> Some special monitors will have noise or even no sound after
> applying the patch 6014ac12.
>
> In patch 6014ac12, it will reset the cts value to 0 for HDMI.
> However, we need disable Enable CTS or M Prog bit. This is
> the initial setting after HW reset.
>
Fixes: 6014ac122ed0 ("drm/i915/audio: set proper N/M in modeset")
> Signed-off-by: Libin Yang <[email protected]>
> ---
> drivers/gpu/drm/i915/intel_audio.c | 15 ++++++++++++---
> 1 file changed, 12 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_audio.c
> b/drivers/gpu/drm/i915/intel_audio.c
> index 813fd74..a472d35 100644
> --- a/drivers/gpu/drm/i915/intel_audio.c
> +++ b/drivers/gpu/drm/i915/intel_audio.c
> @@ -332,6 +332,13 @@ hsw_hdmi_audio_config_update(struct intel_crtc
> *intel_crtc, enum port port,
> int n;
> u32 tmp;
>
> + /* reset CTS value to 0 */
> + tmp = I915_READ(HSW_AUD_M_CTS_ENABLE(pipe));
> + tmp &= ~AUD_CONFIG_M_MASK;
> + tmp &= ~AUD_M_CTS_M_VALUE_INDEX;
> + tmp |= AUD_M_CTS_M_PROG_ENABLE;
> + I915_WRITE(HSW_AUD_M_CTS_ENABLE(pipe), tmp);
> +
> tmp = I915_READ(HSW_AUD_CFG(pipe));
> tmp &= ~AUD_CONFIG_N_VALUE_INDEX;
> tmp &= ~AUD_CONFIG_PIXEL_CLOCK_HDMI_MASK;
> @@ -351,10 +358,12 @@ hsw_hdmi_audio_config_update(struct intel_crtc
> *intel_crtc, enum port port,
>
> I915_WRITE(HSW_AUD_CFG(pipe), tmp);
>
> + /*
> + * Let's disable "Enable CTS or M Prog bit"
> + * and let HW calculate the value
> + */
> tmp = I915_READ(HSW_AUD_M_CTS_ENABLE(pipe));
> - tmp &= ~AUD_CONFIG_M_MASK;
> - tmp &= ~AUD_M_CTS_M_VALUE_INDEX;
> - tmp |= AUD_M_CTS_M_PROG_ENABLE;
> + tmp &= ~AUD_M_CTS_M_PROG_ENABLE;
> I915_WRITE(HSW_AUD_M_CTS_ENABLE(pipe), tmp);
Is it necessary to do the HSW_AUD_M_CTS_ENABLE updates in two places?
Why do you both enable and disable AUD_M_CTS_M_PROG_ENABLE bit here?
BR,
Jani.
> }
--
Jani Nikula, Intel Open Source Technology Center
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