On Thu, Jun 11, 2026 at 12:16 AM Jani Nikula <[email protected]> wrote:
>
> The Tiled Display Topology ID of a DisplayID Tiled Display Topology Data
> Block consists of three fields:
>
> - Tiled Display Manufacturer/Vendor ID Field (3 bytes)
> - Tiled Display Product ID Code Field (2 bytes)
> - Tiled Display Serial Number Field (4 bytes)
>
> i.e. a total of 9 bytes, not 8.
>
> The DisplayID Tiled Display Topology ID is used as the tile group
> identifier.
>
> Update both struct displayid_tiled_block topology_id member and struct
> drm_tile_group group_data member to full 9 bytes.
>
> The group data was missing the last byte of the serial number. I don't
> know whether there are known bug reports that might be linked to this,
> but it's plausible the last byte could be the differentiating part for
> the tile groups, and fewer tile groups might have been created than
> intended.

I pulled out my spec, and indeed I can confirm this is the correct reading!

Reviewed-by: Dave Airlie <[email protected]>

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