[PATCH] drm/amd/display: Add a new dcdebugmask to allow skip detection LT

[PATCH] drm/amd/display: Add a new dcdebugmask to allow skip detection LT

[Wayne Lin]

Under specific embedded scenarios, we might still use DP interface
rather than eDP interface. Under such case, detection link training
is unnecessary.

Add a new dcdebugmas value that can be used to skip the detection LT

Signed-off-by: Wayne Lin <Wayne.Lin@amd.com>
---
 drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 3 +++
 drivers/gpu/drm/amd/include/amd_shared.h          | 5 +++++
 2 files changed, 8 insertions(+)

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
index 4b4e9241619f..2bb347771aa1 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -2020,6 +2020,9 @@ static int amdgpu_dm_init(struct amdgpu_device *adev)
 	if (amdgpu_dc_debug_mask & DC_HDCP_LC_ENABLE_SW_FALLBACK)
 		adev->dm.dc->debug.hdcp_lc_enable_sw_fallback = true;
 
+	if (amdgpu_dc_debug_mask & DC_SKIP_DETECTION_LT)
+		adev->dm.dc->debug.skip_detection_link_training = true;
+
 	adev->dm.dc->debug.visual_confirm = amdgpu_dc_visual_confirm;
 
 	/* TODO: Remove after DP2 receiver gets proper support of Cable ID feature */
diff --git a/drivers/gpu/drm/amd/include/amd_shared.h b/drivers/gpu/drm/amd/include/amd_shared.h
index c8eccee9b023..31de36c9156f 100644
--- a/drivers/gpu/drm/amd/include/amd_shared.h
+++ b/drivers/gpu/drm/amd/include/amd_shared.h
@@ -370,6 +370,11 @@ enum DC_DEBUG_MASK {
 	 * path failure, retry using legacy SW path.
 	 */
 	DC_HDCP_LC_ENABLE_SW_FALLBACK = 0x100000,
+
+	/**
+	 * @DC_SKIP_DETECTION_LT: If set, skip detection link training
+	 */
+	DC_SKIP_DETECTION_LT = 0x200000,
 };
 
 enum amd_dpm_forced_level;
-- 
2.43.0

Re: [PATCH] drm/amd/display: Add a new dcdebugmask to allow skip detection LT

[Chung, ChiaHsuan (Tom)]

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Patch looks good to me.

Just some nitpick may need in commit messages. dcdebugmas -> dcdebugmask

Reviewed-by: Tom Chung <chiahsuan.chung@amd.com>

On 5/21/2025 2:39 PM, Wayne Lin wrote:
> Under specific embedded scenarios, we might still use DP interface
> rather than eDP interface. Under such case, detection link training
> is unnecessary.
>
> Add a new dcdebugmas value that can be used to skip the detection LT
>
> Signed-off-by: Wayne Lin<Wayne.Lin@amd.com>
> ---
>   drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 3 +++
>   drivers/gpu/drm/amd/include/amd_shared.h          | 5 +++++
>   2 files changed, 8 insertions(+)
>
> diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> index 4b4e9241619f..2bb347771aa1 100644
> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> @@ -2020,6 +2020,9 @@ static int amdgpu_dm_init(struct amdgpu_device *adev)
>   	if (amdgpu_dc_debug_mask & DC_HDCP_LC_ENABLE_SW_FALLBACK)
>   		adev->dm.dc->debug.hdcp_lc_enable_sw_fallback = true;
>   
> +	if (amdgpu_dc_debug_mask & DC_SKIP_DETECTION_LT)
> +		adev->dm.dc->debug.skip_detection_link_training = true;
> +
>   	adev->dm.dc->debug.visual_confirm = amdgpu_dc_visual_confirm;
>   
>   	/* TODO: Remove after DP2 receiver gets proper support of Cable ID feature */
> diff --git a/drivers/gpu/drm/amd/include/amd_shared.h b/drivers/gpu/drm/amd/include/amd_shared.h
> index c8eccee9b023..31de36c9156f 100644
> --- a/drivers/gpu/drm/amd/include/amd_shared.h
> +++ b/drivers/gpu/drm/amd/include/amd_shared.h
> @@ -370,6 +370,11 @@ enum DC_DEBUG_MASK {
>   	 * path failure, retry using legacy SW path.
>   	 */
>   	DC_HDCP_LC_ENABLE_SW_FALLBACK = 0x100000,
> +
> +	/**
> +	 * @DC_SKIP_DETECTION_LT: If set, skip detection link training
> +	 */
> +	DC_SKIP_DETECTION_LT = 0x200000,
>   };
>   
>   enum amd_dpm_forced_level;

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