Re: [PATCH 04/21] drm/tilcdc: Add support for DRM bus flags and simplify panel config

["Luca Ceresoli" <luca.ceresoli@bootlin.com>]

On Wed Nov 26, 2025 at 6:35 PM CET, Kory Maincent (TI.com) wrote:
> Migrate CRTC mode configuration to use standard DRM bus flags in
> preparation for removing the tilcdc_panel driver and its custom
> tilcdc_panel_info structure.
>
> Add support for DRM_BUS_FLAG_PIXDATA_DRIVE_NEGEDGE and
> DRM_BUS_FLAG_SYNC_DRIVE_NEGEDGE flags to control pixel clock and sync
> signal edge polarity, while maintaining backward compatibility with the
> existing tilcdc panel info structure.
>
> Simplify several hardware parameters by setting them to fixed defaults
> based on common usage across existing device trees:
> - DMA burst size: 16 (previously configurable via switch statement)
> - AC bias frequency: 255 (previously panel-specific)
> - FIFO DMA request delay: 128 (previously panel-specific)
>
> These parameters show no variation in real-world usage, so hardcoding
> them simplifies the driver without losing functionality.
>
> Preserve FIFO threshold configurability by adding a new "fifo-threshold"
> device tree property at the display controller level, as this parameter
> varies across different display configurations in existing device trees.
>
> Signed-off-by: Kory Maincent (TI.com) <kory.maincent@bootlin.com>

Apart from the "fifo-threshold" property, which as discussed should instead
be inferred from the compatible, the patch looks good. I checked the values
which are being removed and they have all the same value in the code
defaults and all in-tree dts files.

Luca

--
Luca Ceresoli, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com