Re: [RFC PATCH 0/7] add at91sam9 LCDC DRM driver

[Nicolas Ferre <nicolas.ferre@microchip.com>]

On 12/08/2018 at 21:55, Sam Ravnborg wrote:
> The at91sam9263 has a few interesting "GPU" features:
> 
> - 2D memory addressing
>    Data sheet says:
> 	The LCDC can be configured to work on a frame buffer
> 	larger than the actual screen size. By changing the
> 	values in a few registers, it is easy to move the
> 	displayed area along the frame buffer width and height
> 
> - 2D Graphics controller
>    Data sheet says:
> 	The Two D Graphics Controller (TDGC) features a
> 	hardware accelerator which highly simplifies drawing
> 	tasks and graphic management operations.
> 	The hardware accelerator makes it easy to draw lines
> 	and complex polygons and to perform block transfers
> 	within the frame buffer.
> 	The TDGC also features a draw command queue that
> 	automatically executes a more complex drawing function
> 	that is composed of several register accesses.
> 
> The datasheet text is from: chapter 43.9 + chapter 44:
> http://ww1.microchip.com/downloads/en/DeviceDoc/Atmel-6249-32-bit-ARM926EJ-S-Embedded-Microprocessor-SAM9263_Datasheet.pdf
> (No NDA required)

(old memories) this 2D engine prove itself of being quite limited as the 
fill polygon and clipping functions are not working.

> Based on the above, would it be possible to utilise some
> of these features without any dedicated userspace (mesa) support?
> Any other driver that has something similar that can be used
> for inspiration?

This is really an interesting question indeed.

> Or is this in reality a simple GPU that requires a
> dedicated GPU driver?
> 
> 	Sam
> 


-- 
Nicolas Ferre