> -----Original Message-----
> From: Shankar, Uma <uma.shankar@xxxxxxxxx>
> Sent: Monday, May 6, 2024 3:48 PM
> To: intel-gfx@xxxxxxxxxxxxxxxxxxxxx; intel-xe@xxxxxxxxxxxxxxxxxxxxx
> Cc: Borah, Chaitanya Kumar <chaitanya.kumar.borah@xxxxxxxxx>;
> jani.nikula@xxxxxxxxxxxxxxx; Roper, Matthew D
> <matthew.d.roper@xxxxxxxxx>; Shankar, Uma <uma.shankar@xxxxxxxxx>
> 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@xxxxxxxxx>
> ---
> 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@xxxxxxxxx>
> +
> #endif /* __INTEL_AUDIO_REGS_H__ */
> --
> 2.42.0
