On Mon, 06 May 2024, Uma Shankar <uma.shankar@xxxxxxxxx> wrote:
> 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))
Why do we need to check for both display version and the platform?
Especially weird that it's || and not &&.
> + return true;
> +
> + return false;
The whole function is just "return ver == 20 || is_bmg", there's no need
to have the if and two different return locations.
BR,
Jani.
> +}
> +
> /* 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)
> +
> #endif /* __INTEL_AUDIO_REGS_H__ */
--
Jani Nikula, Intel
