Re: [PATCH v4] drm/fourcc: Add Synaptics VideoSmart tiled modifiers

[Randy Li]

> On Nov 24, 2022, at 12:42 AM, Daniel Vetter <daniel@xxxxxxxx> wrote:
> 
> On Wed, Nov 23, 2022 at 10:58:11PM +0800, Jisheng Zhang wrote:
>>> On Wed, Nov 23, 2022 at 05:19:57PM +0800, Hsia-Jun Li wrote:
>>> From: "Hsia-Jun(Randy) Li" <randy.li@xxxxxxxxxxxxx>
>>> Memory Traffic Reduction(MTR) is a module in Synaptics
>>> VideoSmart platform could process lossless compression image
>>> and cache the tile memory line.
>>> Those modifiers only record the parameters would effort pixel
>>> layout or memory layout. Whether physical memory page mapping
>>> is used is not a part of format.
>>> We would allocate the same size of memory for uncompressed
>>> and compressed luma and chroma data, while the compressed buffer
>>> would request two extra planes holding the metadata for
>>> the decompression.
>>> Signed-off-by: Hsia-Jun(Randy) Li <randy.li@xxxxxxxxxxxxx>
>>> ---
>>> include/uapi/drm/drm_fourcc.h | 75 +++++++++++++++++++++++++++++++++++
>>> 1 file changed, 75 insertions(+)
>>> diff --git a/include/uapi/drm/drm_fourcc.h b/include/uapi/drm/drm_fourcc.h
>>> index bc056f2d537d..ca0b4ca70b36 100644
>>> --- a/include/uapi/drm/drm_fourcc.h
>>> +++ b/include/uapi/drm/drm_fourcc.h
>>> @@ -407,6 +407,7 @@ extern "C" {
>>> #define DRM_FORMAT_MOD_VENDOR_ARM     0x08
>>> #define DRM_FORMAT_MOD_VENDOR_ALLWINNER 0x09
>>> #define DRM_FORMAT_MOD_VENDOR_AMLOGIC 0x0a
>>> +#define DRM_FORMAT_MOD_VENDOR_SYNAPTICS 0x0b
>> Any users in the mainline tree?
Not yet. I believe a V4L2 codec would be the first one.
Still there are many patches are requested for v4l2 which currently does not support format modifier. You could find discussion in linux media list.

This does need the agreement from drm maintainers, three of us tend to drop the pixel formats in video4linux2.h only keeping those codec formats in new extended v4l2 format negotiation interface. All the pixel formats should go to drm_fourcc.h while we can’t decide how to present those hardware requests contiguous memory.

We don’t bring those NV12M into drm_fourcc.h, we hate that.
> Note that drm_fourcc.h serves as the vendor-neutral registry for these
> numbers, and they're referenced in both gl and vk extensions. So this is
> the one case where we do _not_ require in-kernel users or open source
> userspace.
> 
The first user for these pixel formats would be the software pixel reader for Gstreamer, I am planning to add the unpacker for the two uncompressed pixel formats.
> If there is someone interested in an in-kernel or open userspace driver
> though it would be really great to have their acks before merging. Just to
> make sure that the modifiers will work with both upstream and downstream
> driver stacks.
This patch have been reviewed internally, it is good enough to describe our pixel formats.
> 
> I just realized that we've failed to document this, I'll type up a patch.

About the format itself, I have sent the document to the mesa, you could find a MR there.
> -Daniel
> 
> 
>>> /* add more to the end as needed */
>>> @@ -1507,6 +1508,80 @@ drm_fourcc_canonicalize_nvidia_format_mod(__u64 modifier)
>>> #define AMD_FMT_MOD_CLEAR(field) \
>>>   (~((__u64)AMD_FMT_MOD_##field##_MASK << AMD_FMT_MOD_##field##_SHIFT))
>>> +/*
>>> + * Synaptics VideoSmart modifiers
>>> + *
>>> + * Tiles could be arranged in Groups of Tiles (GOTs), it is a small tile
>>> + * within a tile. GOT size and layout varies based on platform and
>>> + * performance concern. When the compression is applied, it is possible
>>> + * that we would have two tile type in the GOT, these parameters can't
>>> + * tell the secondary tile type.
>>> + *
>>> + * Besides, an 8 size 4 bytes arrary (32 bytes) would be need to store
>>> + * some compression parameters for a compression meta data plane.
>>> + *
>>> + *       Macro
>>> + * Bits  Param Description
>>> + * ----  ----- -----------------------------------------------------------------
>>> + *
>>> + *  7:0  f     Scan direction description.
>>> + *
>>> + *               0 = Invalid
>>> + *               1 = V4, the scan would always start from vertical for 4 pixel
>>> + *                   then move back to the start pixel of the next horizontal
>>> + *                   direction.
>>> + *               2 = Reserved for future use.
>>> + *
>>> + * 15:8  m     The times of pattern repeat in the right angle direction from
>>> + *             the first scan direction.
>>> + *
>>> + * 19:16 p     The padding bits after the whole scan, could be zero.
>>> + *
>>> + * 20:20 g     GOT packing flag.
>>> + *
>>> + * 23:21 -     Reserved for future use.  Must be zero.
>>> + *
>>> + * 27:24 h     log2(horizontal) of bytes, in GOTs.
>>> + *
>>> + * 31:28 v     log2(vertical) of bytes, in GOTs.
>>> + *
>>> + * 35:32 -     Reserved for future use.  Must be zero.
>>> + *
>>> + * 36:36 c     Compression flag.
>>> + *
>>> + * 55:37 -     Reserved for future use.  Must be zero.
>>> + *
>>> + */
>>> +
>>> +#define DRM_FORMAT_MOD_SYNA_V4_TILED        fourcc_mod_code(SYNAPTICS, 1)
>>> +
>>> +#define DRM_FORMAT_MOD_SYNA_MTR_LINEAR_2D(f, m, p, g, h, v, c) \
>>> +    fourcc_mod_code(SYNAPTICS, ((__u64)((f) & 0xff) | \
>>> +                 ((__u64)((m) & 0xff) << 8) | \
>>> +                 ((__u64)((p) & 0xf) << 16) | \
>>> +                 ((__u64)((g) & 0x1) << 20) | \
>>> +                 ((__u64)((h) & 0xf) << 24) | \
>>> +                 ((__u64)((v) & 0xf) << 28) | \
>>> +                 ((__u64)((c) & 0x1) << 36)))
>>> +
>>> +#define DRM_FORMAT_MOD_SYNA_V4H1 \
>>> +    DRM_FORMAT_MOD_SYNA_MTR_LINEAR_2D(1, 1, 0, 0, 0, 0, 0)
>>> +
>>> +#define DRM_FORMAT_MOD_SYNA_V4H3P8 \
>>> +    DRM_FORMAT_MOD_SYNA_MTR_LINEAR_2D(1, 3, 8, 0, 0, 0, 0)
>>> +
>>> +#define DRM_FORMAT_MOD_SYNA_V4H1_64L4_COMPRESSED \
>>> +    DRM_FORMAT_MOD_SYNA_MTR_LINEAR_2D(1, 1, 0, 1, 6, 2, 1)
>>> +
>>> +#define DRM_FORMAT_MOD_SYNA_V4H3P8_64L4_COMPRESSED \
>>> +    DRM_FORMAT_MOD_SYNA_MTR_LINEAR_2D(1, 3, 8, 1, 6, 2, 1)
>>> +
>>> +#define DRM_FORMAT_MOD_SYNA_V4H1_128L128_COMPRESSED \
>>> +    DRM_FORMAT_MOD_SYNA_MTR_LINEAR_2D(1, 1, 0, 1, 7, 7, 1)
>>> +
>>> +#define DRM_FORMAT_MOD_SYNA_V4H3P8_128L128_COMPRESSED \
>>> +    DRM_FORMAT_MOD_SYNA_MTR_LINEAR_2D(1, 3, 8, 1, 7, 7, 1)
>>> +
>>> #if defined(__cplusplus)
>>> }
>>> #endif
>>> --
>>> 2.17.1
> 
> -- 
> Daniel Vetter
> Software Engineer, Intel Corporation
> http://blog.ffwll.ch