Re: [PATCH 03/13] drm/amd/display: parse display name from drm_eld

[Jani Nikula <jani.nikula@linux.intel.com>]

On Fri, 11 Apr 2025, Melissa Wen <mwen@igalia.com> wrote:
> We don't need to parse dc_edid to get the display name since it's
> already set in drm_eld which in turn had it values updated when updating
> connector with the opaque drm_edid.
>
> Signed-off-by: Melissa Wen <mwen@igalia.com>
> ---
>  .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c  | 10 ++++++----
>  1 file changed, 6 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
> index e93adb7e48a5..faea6b7fb3f3 100644
> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
> @@ -34,7 +34,7 @@
>  #include <drm/amdgpu_drm.h>
>  #include <drm/drm_edid.h>
>  #include <drm/drm_fixed.h>
> -
> +#include <drm/drm_eld.h>
>  #include "dm_services.h"
>  #include "amdgpu.h"
>  #include "dc.h"
> @@ -90,6 +90,7 @@ static void apply_edid_quirks(struct drm_device *dev, struct edid *edid, struct
>  	}
>  }
>  
> +#define AMDGPU_ELD_DISPLAY_NAME_SIZE_IN_CHARS 13
>  /**
>   * dm_helpers_parse_edid_caps() - Parse edid caps
>   *
> @@ -132,9 +133,10 @@ enum dc_edid_status dm_helpers_parse_edid_caps(
>  	edid_caps->manufacture_week = product_id.week_of_manufacture;
>  	edid_caps->manufacture_year = product_id.year_of_manufacture;
>  
> -	drm_edid_get_monitor_name(edid_buf,
> -				  edid_caps->display_name,
> -				  AUDIO_INFO_DISPLAY_NAME_SIZE_IN_CHARS);
> +	memset(edid_caps->display_name, 0, AUDIO_INFO_DISPLAY_NAME_SIZE_IN_CHARS);
> +	memcpy(edid_caps->display_name,
> +	       &connector->eld[DRM_ELD_MONITOR_NAME_STRING],
> +	       AMDGPU_ELD_DISPLAY_NAME_SIZE_IN_CHARS);

It's not that simple. The monitor name in ELD is not fixed length (see
drm_eld_mnl()) and neither is it guaranteed to be NUL terminated.

BR,
Jani.


>  
>  	edid_caps->edid_hdmi = connector->display_info.is_hdmi;

-- 
Jani Nikula, Intel