Re: [igt-dev] [PATCH i-g-t v3 6/7] lib/edid: Add support for making DisplayID tile blocks

[Juha-Pekka Heikkila <juhapekka.heikkila@gmail.com>]

Reviewed-by: Juha-Pekka Heikkila <juhapekka.heikkila@gmail.com>

On 1.6.2023 19.13, Ville Syrjala wrote:
> From: Ville Syrjälä <ville.syrjala@linux.intel.com>
> 
> We want to test tiled display support without actually having tiled
> displays. To that end we will want to construct fake tile infromation
> and append it to the EDID.
> 
> v2: Document the functiosn (Juha-Pekka)
> 
> Cc: Juha-Pekka Heikkila <juhapekka.heikkila@gmail.com>
> Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> ---
>   lib/igt_edid.c | 120 +++++++++++++++++++++++++++++++++++++++++++++++++
>   lib/igt_edid.h |  49 ++++++++++++++++++++
>   2 files changed, 169 insertions(+)
> 
> diff --git a/lib/igt_edid.c b/lib/igt_edid.c
> index 68dc4f75478b..80dcea11275d 100644
> --- a/lib/igt_edid.c
> +++ b/lib/igt_edid.c
> @@ -578,3 +578,123 @@ void edid_ext_set_cea(struct edid_ext *ext, size_t data_blocks_size,
>   	cea->dtd_start = 4 + data_blocks_size;
>   	cea->misc = flags | num_native_dtds;
>   }
> +
> +/**
> + * dispid_block_tiled:
> + * @ptr: The DisplayID data block
> + * @num_htiles: Total number of horizontal tiles
> + * @num_vtiles: Total number of vertical tiles
> + * @htile: Horizontal tile location
> + * @vtile: Vertical tile location
> + * @hsize: Horizontal size
> + * @vsize: Vertical size
> + * @topology_id: Tiled display topology ID
> + *
> + * Fill a DisplayID tiled display topology data block
> + *
> + * Returns:
> + * A pointer to the next data block
> + */
> +void *dispid_block_tiled(void *ptr,
> +			 int num_htiles, int num_vtiles,
> +			 int htile, int vtile,
> +			 int hsize, int vsize,
> +			 const char *topology_id)
> +{
> +	struct dispid_block_header *block = ptr;
> +	struct dispid_tiled_block *tiled = (void*)(block + 1);
> +	size_t len;
> +
> +	block->tag = 0x12;
> +	block->rev = 0;
> +	block->num_bytes = sizeof(*tiled);
> +
> +	num_htiles--;
> +	num_vtiles--;
> +	hsize--;
> +	vsize--;
> +
> +	tiled->tile_caps =
> +		DISPID_MULTI_TILE_AT_TILE_LOCATION |
> +		DISPID_SINGLE_TILE_AT_TILE_LOCATION;
> +
> +	tiled->topo[0] = (num_htiles & 0xf) << 4 |
> +		(num_vtiles & 0xf) << 0;
> +
> +	tiled->topo[1] = (htile & 0xf) << 4 |
> +		(vtile & 0xf) << 0;
> +
> +	tiled->topo[2] = (num_htiles >> 4) << 6 |
> +		(num_vtiles >> 4) << 4 |
> +		(htile >> 4) << 2 |
> +		(vtile >> 4) << 0;
> +
> +	tiled->tile_size[0] = hsize;
> +	tiled->tile_size[1] = hsize >> 8;
> +	tiled->tile_size[2] = vsize;
> +	tiled->tile_size[3] = vsize >> 8;
> +
> +	len = min(strlen(topology_id), sizeof(tiled->topology_id));
> +	memcpy(tiled->topology_id, topology_id, len);
> +
> +	return tiled + 1;
> +}
> +
> +/**
> + * edid_ext_dispid:
> + * @ext: EDID extension block
> + *
> + * Mark the EDID extentions block as DisplayID.
> +
> + * Returns:
> + * A pointer to the contained DisplayID.
> + */
> +void *edid_ext_dispid(struct edid_ext *ext)
> +{
> +	struct edid_dispid *dispid = &ext->data.dispid;
> +
> +	edid_ext_set_displayid(ext);
> +
> +	return dispid;
> +}
> +
> +/**
> + * dispid_init:
> + * @ptr: Pointer to the DisplayID
> + *
> + * Initialize the DisplayID header.
> + *
> + * Returns:
> + * A pointer to the first data block.
> + */
> +void *dispid_init(void *ptr)
> +{
> +	struct dispid_header *dispid = ptr;
> +
> +	dispid->rev = 0x10;
> +	dispid->prod_id = 0x3;
> +	dispid->ext_count = 0;
> +
> +	return dispid + 1;
> +}
> +
> +/**
> + * dispid_done:
> + * @dispid: Pointer to the DisplayID
> + * @ptr: Pointer to the end of the DisplayID (the checksum byte)
> + *
> + * Finalize the DisplayID (fill the number of bytes and checksum).
> + *
> + * Returns:
> + * A pointer just past the end of the DisplayID.
> + */
> +void *dispid_done(struct dispid_header *dispid, void *ptr)
> +{
> +	int bytes = ptr - (void *)dispid;
> +
> +	dispid->num_bytes = bytes - sizeof(*dispid);
> +
> +	*(uint8_t *)ptr = compute_checksum((void*)dispid, bytes + 1);
> +
> +	return ptr + 1;
> +}
> diff --git a/lib/igt_edid.h b/lib/igt_edid.h
> index 85a9ef5e1a25..02645345f0d0 100644
> --- a/lib/igt_edid.h
> +++ b/lib/igt_edid.h
> @@ -303,6 +303,44 @@ struct edid_cea {
>   	uint8_t checksum;
>   } __attribute__((packed));
>   
> +enum dispid_tile_caps {
> +	DISPID_SINGLE_PHYSICAL_ENCLOSURE = 1 << 7,
> +	DISPID_BEZEL_INFORMATION_PRESENT = 1 << 6,
> +	DISPID_MULTI_TILE_UNKNOWN = 0 << 3,
> +	DISPID_MULTI_TILE_AT_TILE_LOCATION = 1 << 3,
> +	DISPID_SINGLE_TILE_UNKNOWN = 0 << 0,
> +	DISPID_SINGLE_TILE_AT_TILE_LOCATION = 1 << 0,
> +	DISPID_SINGLE_TILE_SCALED_FULLSCREEN = 2 << 0,
> +	DISPID_SINGLE_TILE_CLONED_TO_ALL_TILES = 3 << 0,
> +};
> +
> +struct dispid_header {
> +	uint8_t rev;
> +	uint8_t num_bytes;
> +	uint8_t prod_id;
> +	uint8_t ext_count;
> +} __attribute__((packed));
> +
> +struct dispid_block_header {
> +	uint8_t tag;
> +	uint8_t rev;
> +	uint8_t num_bytes;
> +} __attribute__((packed));
> +
> +struct dispid_tiled_block {
> +	uint8_t tile_caps;
> +	uint8_t topo[3];
> +	uint8_t tile_size[4];
> +	uint8_t tile_pixel_bezel[5];
> +	uint8_t topology_id[9];
> +} __attribute__((packed));
> +
> +struct edid_dispid {
> +	struct dispid_header header;
> +	char data[122];
> +	uint8_t checksum;
> +} __attribute__((packed));
> +
>   enum edid_ext_tag {
>   	EDID_EXT_CEA = 0x02,
>   	EDID_EXT_DISPLAYID = 0x70,
> @@ -329,6 +367,7 @@ struct edid_ext {
>   	union {
>   		struct edid_cea cea;
>   		struct edid_tile tile;
> +		struct edid_dispid dispid;
>   	} data;
>   } __attribute__((packed));
>   
> @@ -408,4 +447,14 @@ void edid_ext_set_cea(struct edid_ext *ext, size_t data_blocks_size,
>   		      uint8_t num_native_dtds, uint8_t flags);
>   
>   void edid_ext_set_displayid(struct edid_ext *ext);
> +
> +void *edid_ext_dispid(struct edid_ext *ext);
> +void *dispid_init(void *ptr);
> +void *dispid_done(struct dispid_header *dispid, void *ptr);
> +void *dispid_block_tiled(void *ptr,
> +			 int num_htiles, int num_vtiles,
> +			 int htile, int vtile,
> +			 int hsize, int vsize,
> +			 const char *topology_id);
> +
>   #endif