> -----Original Message-----
> From: Nikula, Jani <jani.nikula@xxxxxxxxx>
> Sent: 07 September 2023 14:58
> To: dri-devel@xxxxxxxxxxxxxxxxxxxxx
> Cc: intel-gfx@xxxxxxxxxxxxxxxxxxxxx; Nikula, Jani <jani.nikula@xxxxxxxxx>;
> Golani, Mitulkumar Ajitkumar <mitulkumar.ajitkumar.golani@xxxxxxxxx>
> Subject: [PATCH 6/6] drm/eld: add helpers to modify the SADs of an ELD
>
> Occasionally it's necessary for drivers to modify the SADs of an ELD, but it's
> not so cool to have drivers poke at the ELD buffer directly.
>
> Using the helpers to translate between 3-byte SAD and struct cea_sad, add
> ELD helpers to get/set the SADs from/to an ELD.
>
> Cc: Mitul Golani <mitulkumar.ajitkumar.golani@xxxxxxxxx>
> Signed-off-by: Jani Nikula <jani.nikula@xxxxxxxxx>
> ---
> Documentation/gpu/drm-kms-helpers.rst | 3 ++
> drivers/gpu/drm/Makefile | 1 +
> drivers/gpu/drm/drm_eld.c | 55 +++++++++++++++++++++++++++
> include/drm/drm_eld.h | 5 +++
> 4 files changed, 64 insertions(+)
> create mode 100644 drivers/gpu/drm/drm_eld.c
>
> diff --git a/Documentation/gpu/drm-kms-helpers.rst
> b/Documentation/gpu/drm-kms-helpers.rst
> index f0f93aa62545..df91b7cd992e 100644
> --- a/Documentation/gpu/drm-kms-helpers.rst
> +++ b/Documentation/gpu/drm-kms-helpers.rst
> @@ -366,6 +366,9 @@ EDID Helper Functions Reference .. kernel-doc::
> include/drm/drm_eld.h
> :internal:
>
> +.. kernel-doc:: drivers/gpu/drm/drm_eld.c
> + :export:
> +
> SCDC Helper Functions Reference
> ===============================
>
> diff --git a/drivers/gpu/drm/Makefile b/drivers/gpu/drm/Makefile index
> 215e78e79125..632e74d823e8 100644
> --- a/drivers/gpu/drm/Makefile
> +++ b/drivers/gpu/drm/Makefile
> @@ -22,6 +22,7 @@ drm-y := \
> drm_drv.o \
> drm_dumb_buffers.o \
> drm_edid.o \
> + drm_eld.o \
> drm_encoder.o \
> drm_file.o \
> drm_fourcc.o \
> diff --git a/drivers/gpu/drm/drm_eld.c b/drivers/gpu/drm/drm_eld.c new
> file mode 100644 index 000000000000..34e0d71c3550
> --- /dev/null
> +++ b/drivers/gpu/drm/drm_eld.c
> @@ -0,0 +1,55 @@
> +// SPDX-License-Identifier: MIT
> +/*
> + * Copyright © 2023 Intel Corporation
> + */
> +
> +#include <drm/drm_edid.h>
> +#include <drm/drm_eld.h>
> +
> +#include "drm_internal.h"
> +
> +/**
> + * drm_eld_sad_get - get SAD from ELD to struct cea_sad
> + * @eld: ELD buffer
> + * @i: SAD number
> + * @cta_sad: destination struct cea_sad
> + *
> + * @return: 0 on success, or negative on errors */ int
> +drm_eld_sad_get(const u8 *eld, int i, struct cea_sad *cta_sad) {
Could we use a more descriptive variable name than 'i' for better code readability in the functions drm_eld_sad_get and drm_eld_sad_set?
possibly something like, `sad_number` or `index` ?
Regards,
Mitul
> + const u8 *sad;
> +
> + if (i >= drm_eld_sad_count(eld))
> + return -EINVAL;
> +
> + sad = eld + DRM_ELD_CEA_SAD(drm_eld_mnl(eld), i);
> +
> + drm_edid_cta_sad_set(cta_sad, sad);
> +
> + return 0;
> +}
> +EXPORT_SYMBOL(drm_eld_sad_get);
> +
> +/**
> + * drm_eld_sad_set - set SAD to ELD from struct cea_sad
> + * @eld: ELD buffer
> + * @i: SAD number
> + * @cta_sad: source struct cea_sad
> + *
> + * @return: 0 on success, or negative on errors */ int
> +drm_eld_sad_set(u8 *eld, int i, const struct cea_sad *cta_sad) {
> + u8 *sad;
> +
> + if (i >= drm_eld_sad_count(eld))
> + return -EINVAL;
> +
> + sad = eld + DRM_ELD_CEA_SAD(drm_eld_mnl(eld), i);
> +
> + drm_edid_cta_sad_get(cta_sad, sad);
> +
> + return 0;
> +}
> +EXPORT_SYMBOL(drm_eld_sad_set);
> diff --git a/include/drm/drm_eld.h b/include/drm/drm_eld.h index
> 7b674256b9aa..5b320157684c 100644
> --- a/include/drm/drm_eld.h
> +++ b/include/drm/drm_eld.h
> @@ -8,6 +8,8 @@
>
> #include <linux/types.h>
>
> +struct cea_sad;
> +
> /* ELD Header Block */
> #define DRM_ELD_HEADER_BLOCK_SIZE 4
>
> @@ -75,6 +77,9 @@ static inline int drm_eld_mnl(const u8 *eld)
> return (eld[DRM_ELD_CEA_EDID_VER_MNL] &
> DRM_ELD_MNL_MASK) >> DRM_ELD_MNL_SHIFT; }
>
> +int drm_eld_sad_get(const u8 *eld, int i, struct cea_sad *cta_sad); int
> +drm_eld_sad_set(u8 *eld, int i, const struct cea_sad *cta_sad);
> +
> /**
> * drm_eld_sad - Get ELD SAD structures.
> * @eld: pointer to an eld memory structure with sad_count set
> --
> 2.39.2
