[PATCH v4 1/1] drm/mediatek: dp: Add sdp path reset

[CK Hu (胡俊光)]

Hi, Liankun:

On Thu, 2024-11-28 at 10:37 +0800, Liankun Yang wrote:
> When using type-c to type-c to connect to the monitor,
> the sound plays normally. If you unplug the type-c and
> connect the type-c to hdmi dongle to the monitor, there will be noise.
> 
> By capturing the audio data, it is found that
> the data position is messy, and there is no error in the data.
> 
> Through experiments, it can be restored by resetting the SDP path
> when unplugging it.

Reviewed-by: CK Hu <ck.hu at mediatek.com>

> 
> Signed-off-by: Liankun Yang <liankun.yang at mediatek.com>
> Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno at collabora.com>
> ---
> Changes in V4:
> - Fix align to the right of '('.
> Per suggestion from the previous thread:
> https://urldefense.com/v3/__https://patchwork.kernel.org/project/linux-mediatek/patch/20240925064854.23065-1-liankun.yang@mediatek.com/__;!!CTRNKA9wMg0ARbw!moBIboZU1a4UlCJ0PNdls-Wyg8zCbx_60VUFdSkCnk5IXzWsiAnF1DpO_4qFz0xvDoTsAKkDVd38PvIu2EFntv4$ 
> 
> Changes in V3:
> - No change.
> Per suggestion from the previous thread:
> https://urldefense.com/v3/__https://patchwork.kernel.org/project/linux-mediatek/patch/20240923132521.22785-1-liankun.yang@mediatek.com/__;!!CTRNKA9wMg0ARbw!moBIboZU1a4UlCJ0PNdls-Wyg8zCbx_60VUFdSkCnk5IXzWsiAnF1DpO_4qFz0xvDoTsAKkDVd38PvIusbUGckk$ 
> 
> Changes in V2:
> - Fix build error.
> Per suggestion from the previous thread:
> https://urldefense.com/v3/__https://patchwork.kernel.org/project/linux-mediatek/patch/20240923133610.23728-1-liankun.yang@mediatek.com/__;!!CTRNKA9wMg0ARbw!moBIboZU1a4UlCJ0PNdls-Wyg8zCbx_60VUFdSkCnk5IXzWsiAnF1DpO_4qFz0xvDoTsAKkDVd38PvIutNJ46WI$ 
> ---
>  drivers/gpu/drm/mediatek/mtk_dp.c     | 15 +++++++++++++++
>  drivers/gpu/drm/mediatek/mtk_dp_reg.h |  1 +
>  2 files changed, 16 insertions(+)
> 
> diff --git a/drivers/gpu/drm/mediatek/mtk_dp.c b/drivers/gpu/drm/mediatek/mtk_dp.c
> index 1cc916b16471..4f4233bd83f7 100644
> --- a/drivers/gpu/drm/mediatek/mtk_dp.c
> +++ b/drivers/gpu/drm/mediatek/mtk_dp.c
> @@ -1135,6 +1135,18 @@ static void mtk_dp_digital_sw_reset(struct mtk_dp *mtk_dp)
>  			   0, DP_TX_TRANSMITTER_4P_RESET_SW_DP_TRANS_P0);
>  }
>  
> +static void mtk_dp_sdp_path_reset(struct mtk_dp *mtk_dp)
> +{
> +	mtk_dp_update_bits(mtk_dp, MTK_DP_ENC0_P0_3004,
> +			   SDP_RESET_SW_DP_ENC0_P0,
> +			   SDP_RESET_SW_DP_ENC0_P0);
> +
> +	/* Wait for sdp path reset to complete */
> +	usleep_range(1000, 5000);
> +	mtk_dp_update_bits(mtk_dp, MTK_DP_ENC0_P0_3004,
> +			   0, SDP_RESET_SW_DP_ENC0_P0);
> +}
> +
>  static void mtk_dp_set_lanes(struct mtk_dp *mtk_dp, int lanes)
>  {
>  	mtk_dp_update_bits(mtk_dp, MTK_DP_TRANS_P0_35F0,
> @@ -2397,6 +2409,9 @@ static void mtk_dp_bridge_atomic_disable(struct drm_bridge *bridge,
>  			   DP_PWR_STATE_BANDGAP_TPLL,
>  			   DP_PWR_STATE_MASK);
>  
> +	/* SDP path reset sw*/
> +	mtk_dp_sdp_path_reset(mtk_dp);
> +
>  	/* Ensure the sink is muted */
>  	msleep(20);
>  }
> diff --git a/drivers/gpu/drm/mediatek/mtk_dp_reg.h b/drivers/gpu/drm/mediatek/mtk_dp_reg.h
> index 709b79480693..8ad7a9cc259e 100644
> --- a/drivers/gpu/drm/mediatek/mtk_dp_reg.h
> +++ b/drivers/gpu/drm/mediatek/mtk_dp_reg.h
> @@ -86,6 +86,7 @@
>  #define MTK_DP_ENC0_P0_3004			0x3004
>  #define VIDEO_M_CODE_SEL_DP_ENC0_P0_MASK		BIT(8)
>  #define DP_TX_ENCODER_4P_RESET_SW_DP_ENC0_P0		BIT(9)
> +#define SDP_RESET_SW_DP_ENC0_P0				BIT(13)
>  #define MTK_DP_ENC0_P0_3010			0x3010
>  #define HTOTAL_SW_DP_ENC0_P0_MASK			GENMASK(15, 0)
>  #define MTK_DP_ENC0_P0_3014			0x3014