On Thu, Feb 28, 2019 at 11:15:11AM +0100, Daniel Vetter wrote:
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 ...
Kind of ... :)
Like Ayan is saying, the numbers relate to the spec, not what silicon vendors implement. AFBC defines a set of "compression parameters" (for the lack of a better definition) and then various blocks implement the parameters that they need. Some might only encode buffers, in which case they will ignore or skip all the options related to decoding, but will still claim to be compliant with AFBC 1.x.
The best way to look at AFBC from an implementation PoV is to look at the modifiers and determine if they are supported by a certain silicon IP or not. The fact that a given modifier has been introduced by AFBC spec number 1.2 or 1.1 should not be relevant.
Best regards, Liviu
-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@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.comhttp://www.baylibre.com
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-- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch