AFBC versions modifiers

[Daniel Vetter]

On Wed, Feb 27, 2019 at 03:41:35PM +0000, Ayan Halder wrote:
> Hi Neil,
> 
> AFBC 1.0 does not support (ignoring common prefix AFBC_FORMAT_MOD_) BLOCK_SIZE_32x8, BLOCK_SIZE_64x4, BLOCK_SIZE_32x8_64x4
> CBR, TILED, SC, DB and BCH  modifiers.
> 
> AFBC 1.2 does not support BLOCK_SIZE_64x4, BLOCK_SIZE_32x8_64x4, DB and BCH modifiers.

Would be great to add that to kernel comments in drm_fourcc.h ...
-Daniel

> 
> Beyond that it's very hard to say. The AFBC version numbers refer to versions of the specification, but aren't very useful for describing the actual bitstream format.
> To determine which modifiers _are_ supported, you will really need to get technical documentation from the SoC vendor
> 
> Regards,
> Ayan Kumar Halder
> 
> ________________________________
> From: Neil Armstrong <narmstrong at baylibre.com>
> Sent: Tuesday, February 26, 2019 2:15 PM
> To: Ayan Halder; Liviu Dudau
> Cc: DRI Development
> Subject: AFBC versions modifiers
> 
> Hi Ayan,
> 
> Could you help distinguish which are the AFBC modifiers for each version of AFBC ?
> 
> The Amlogic SoCs embeds an AFBC 1.0 compatible decoder, then the newer SoCs embeds an AFBC 1.2 decoder,
> I assume the modifiers before the patch "drm/fourcc: Add modifier defininitions for AFBC 1.3" are
> valid for AFBC 1.2, but what is the subset for 1.0 and 1.1 ?
> 
> Thanks,
> Neil
> 
> --
> Neil Armstrong
> Embedded Linux Software Engineer
> BayLibre - At the Heart of Embedded Linux
> www.baylibre.com<http://www.baylibre.com>

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-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch