[PATCH v4 10/14] drm/amd/display: add a mid-layer file to handle EDID in DC

[Mario Limonciello]

On 6/13/2025 9:58 AM, Melissa Wen wrote:
> From: Rodrigo Siqueira <siqueira at igalia.com>
> 
> Since DC is a shared code, this commit introduces a new file to work as
> a mid-layer in DC for the edid manipulation.
> 
> v3:
> - rebase on top of asdn
Can you put changelog below cutlist (---)?
> 
> Signed-off-by: Rodrigo Siqueira <siqueira at igalia.com>
> Co-developed-by: Melissa Wen <mwen at igalia.com>
> Signed-off-by: Melissa Wen <mwen at igalia.com>
> ---
>   .../gpu/drm/amd/display/amdgpu_dm/Makefile    |  1 +
>   .../gpu/drm/amd/display/amdgpu_dm/dc_edid.c   | 19 +++++++++++++++++++
>   .../gpu/drm/amd/display/amdgpu_dm/dc_edid.h   | 11 +++++++++++
>   .../drm/amd/display/dc/link/link_detection.c  | 17 +++--------------
>   4 files changed, 34 insertions(+), 14 deletions(-)
>   create mode 100644 drivers/gpu/drm/amd/display/amdgpu_dm/dc_edid.c
>   create mode 100644 drivers/gpu/drm/amd/display/amdgpu_dm/dc_edid.h
> 
> diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/Makefile b/drivers/gpu/drm/amd/display/amdgpu_dm/Makefile
> index 7329b8cc2576..09cb94d8e0e4 100644
> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/Makefile
> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/Makefile
> @@ -39,6 +39,7 @@ AMDGPUDM = \
>   	amdgpu_dm_psr.o \
>   	amdgpu_dm_replay.o \
>   	amdgpu_dm_quirks.o \
> +	dc_edid.o \
>   	amdgpu_dm_wb.o
>   
>   ifdef CONFIG_DRM_AMD_DC_FP
> diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/dc_edid.c b/drivers/gpu/drm/amd/display/amdgpu_dm/dc_edid.c
> new file mode 100644
> index 000000000000..fab873b091f5
> --- /dev/null
> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/dc_edid.c
> @@ -0,0 +1,19 @@
> +// SPDX-License-Identifier: MIT
> +#include "amdgpu_dm/dc_edid.h"
> +#include "dc.h"
> +
> +bool dc_edid_is_same_edid(struct dc_sink *prev_sink,
> +			  struct dc_sink *current_sink)
> +{
> +	struct dc_edid *old_edid = &prev_sink->dc_edid;
> +	struct dc_edid *new_edid = &current_sink->dc_edid;
> +
> +       if (old_edid->length != new_edid->length)
> +               return false;
> +
> +       if (new_edid->length == 0)
> +               return false;
> +
> +       return (memcmp(old_edid->raw_edid,
> +                      new_edid->raw_edid, new_edid->length) == 0);
> +}
> diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/dc_edid.h b/drivers/gpu/drm/amd/display/amdgpu_dm/dc_edid.h
> new file mode 100644
> index 000000000000..7e3b1177bc8a
> --- /dev/null
> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/dc_edid.h
> @@ -0,0 +1,11 @@
> +/* SPDX-License-Identifier: MIT */
> +
> +#ifndef __DC_EDID_H__
> +#define __DC_EDID_H__
> +
> +#include "dc.h"
> +
> +bool dc_edid_is_same_edid(struct dc_sink *prev_sink,
> +			  struct dc_sink *current_sink);
> +
> +#endif /* __DC_EDID_H__ */
> diff --git a/drivers/gpu/drm/amd/display/dc/link/link_detection.c b/drivers/gpu/drm/amd/display/dc/link/link_detection.c
> index 863c24fe1117..344356e26f8b 100644
> --- a/drivers/gpu/drm/amd/display/dc/link/link_detection.c
> +++ b/drivers/gpu/drm/amd/display/dc/link/link_detection.c
> @@ -48,6 +48,8 @@
>   #include "dm_helpers.h"
>   #include "clk_mgr.h"
>   
> +#include "dc_edid.h"

There's a problem with the header location.  If you're naming it 
dc_edid.h but putting the header in amdgpu_dm/ directory then it's only 
going to compile for amdgpu.

I think dc_edid.h needs to go into dc/ directory.

> +
>    // Offset DPCD 050Eh == 0x5A
>   #define MST_HUB_ID_0x5A  0x5A
>   
> @@ -617,18 +619,6 @@ static bool detect_dp(struct dc_link *link,
>   	return true;
>   }
>   
> -static bool is_same_edid(struct dc_edid *old_edid, struct dc_edid *new_edid)
> -{
> -	if (old_edid->length != new_edid->length)
> -		return false;
> -
> -	if (new_edid->length == 0)
> -		return false;
> -
> -	return (memcmp(old_edid->raw_edid,
> -		       new_edid->raw_edid, new_edid->length) == 0);
> -}
> -
>   static bool wait_for_entering_dp_alt_mode(struct dc_link *link)
>   {
>   
> @@ -1105,8 +1095,7 @@ static bool detect_link_and_local_sink(struct dc_link *link,
>   		// Check if edid is the same
>   		if ((prev_sink) &&
>   		    (edid_status == EDID_THE_SAME || edid_status == EDID_OK))
> -			same_edid = is_same_edid(&prev_sink->dc_edid,
> -						 &sink->dc_edid);
> +			same_edid = dc_edid_is_same_edid(prev_sink, sink);
>   
>   		if (sink->edid_caps.panel_patch.skip_scdc_overwrite)
>   			link->ctx->dc->debug.hdmi20_disable = true;