[v3] drm/i915: Implement Audio WA_14020863754

[Borah, Chaitanya Kumar]

> -----Original Message-----
> From: Shankar, Uma <uma.shankar at intel.com>
> Sent: Monday, May 6, 2024 3:48 PM
> To: intel-gfx at lists.freedesktop.org; intel-xe at lists.freedesktop.org
> Cc: Borah, Chaitanya Kumar <chaitanya.kumar.borah at intel.com>;
> jani.nikula at linux.intel.com; Roper, Matthew D
> <matthew.d.roper at intel.com>; Shankar, Uma <uma.shankar at intel.com>
> Subject: [v3] drm/i915: Implement Audio WA_14020863754
> 
> WA_14020863754: Corner case with Min Hblank Fix can cause audio hang
> 
> Issue: Previously a fix was made to avoid issues with extremely small hblanks,
> called the "Min Hblank Fix". However, this can potentially cause an audio
> hang.
> 
> Workaround :
> During "Audio Programming Sequence" Audio Enabling - When DP mode is
> enabled Set mmio offset 0x65F1C bit 18 = 1b, before step #1 "Enable audio
> Presence Detect"
> 
> During "Audio Programming Sequence" Audio Disabling - When DP mode is
> enabled Clear mmio offset 0x65F1C bit 18 = 0b, after step #6 "Disable Audio
> PD (Presence Detect)"
> If not clearing PD bit, must also not clear 0x65F1C bit 18 (leave = 1b)
> 
> v2: Update the platform checks (Jani Nikula)
> 
> v3: Limited the WA to LNL and BMG, added a helper (Matt Roper)
> 
> Signed-off-by: Uma Shankar <uma.shankar at intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_audio.c     | 18 ++++++++++++++++++
>  .../gpu/drm/i915/display/intel_audio_regs.h    |  3 +++
>  2 files changed, 21 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_audio.c
> b/drivers/gpu/drm/i915/display/intel_audio.c
> index ed81e1466c4b..cb055c16dd98 100644
> --- a/drivers/gpu/drm/i915/display/intel_audio.c
> +++ b/drivers/gpu/drm/i915/display/intel_audio.c
> @@ -183,6 +183,18 @@ static const struct hdmi_aud_ncts
> hdmi_aud_ncts_36bpp[] = {
>  	{ 192000, TMDS_445_5M, 20480, 371250 },  };
> 
> +/*
> + * WA_14020863754: Implement Audio Workaround
> + * Corner case with Min Hblank Fix can cause audio hang  */ static bool
> +needs_wa_14020863754(struct drm_i915_private *i915) {
> +	if (DISPLAY_VER(i915) == 20 || IS_BATTLEMAGE(i915))
> +		return true;
> +
> +	return false;
> +}
> +
>  /* get AUD_CONFIG_PIXEL_CLOCK_HDMI_* value for mode */  static u32
> audio_config_hdmi_pixel_clock(const struct intel_crtc_state *crtc_state)  {
> @@ -415,6 +427,9 @@ static void hsw_audio_codec_disable(struct
> intel_encoder *encoder,
>  	intel_de_rmw(i915, HSW_AUD_PIN_ELD_CP_VLD,
>  		     AUDIO_OUTPUT_ENABLE(cpu_transcoder), 0);
> 
> +	if (needs_wa_14020863754(i915))
> +		intel_de_rmw(i915, AUD_CHICKENBIT_REG3,
> CHICKEN3_SPARE18, 0);
> +
>  	mutex_unlock(&i915->display.audio.mutex);
>  }
> 
> @@ -540,6 +555,9 @@ static void hsw_audio_codec_enable(struct
> intel_encoder *encoder,
>  	if (intel_crtc_has_type(crtc_state, INTEL_OUTPUT_DP))
>  		enable_audio_dsc_wa(encoder, crtc_state);
> 
> +	if (needs_wa_14020863754(i915))
> +		intel_de_rmw(i915, AUD_CHICKENBIT_REG3, 0,
> CHICKEN3_SPARE18);
> +
>  	/* Enable audio presence detect */
>  	intel_de_rmw(i915, HSW_AUD_PIN_ELD_CP_VLD,
>  		     0, AUDIO_OUTPUT_ENABLE(cpu_transcoder));
> diff --git a/drivers/gpu/drm/i915/display/intel_audio_regs.h
> b/drivers/gpu/drm/i915/display/intel_audio_regs.h
> index 88ea2740365d..7de82cd3380e 100644
> --- a/drivers/gpu/drm/i915/display/intel_audio_regs.h
> +++ b/drivers/gpu/drm/i915/display/intel_audio_regs.h
> @@ -164,4 +164,7 @@
> 
> _VLV_AUD_PORT_EN_D_DBG)
>  #define VLV_AMP_MUTE		        (1 << 1)
> 
> +#define AUD_CHICKENBIT_REG3		_MMIO(0x65F1C)
> +#define  CHICKEN3_SPARE18		REG_BIT(18)

Nit. This bit seems to have a name now (Bspec-69036). Otherwise, LGTM.

Reviewed-by: Chaitanya Kumar Borah <chaitanya.kumar.borah at intel.com>



> +
>  #endif /* __INTEL_AUDIO_REGS_H__ */
> --
> 2.42.0