linux-kernel - Re: [PATCH] drm: add modifiers for MediaTek tiled formats

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Message-ID: <f9dd18f5-c239-4d96-b0e8-e11e9712fc8a@collabora.com>
Date: Wed, 18 Dec 2024 20:20:26 -0400
From: Eric Smith <eric.smith@...labora.com>
To: Daniel Stone <daniel@...ishbar.org>
Cc: Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
 Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>,
 David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>,
 kernel@...labora.com, dri-devel@...ts.freedesktop.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH] drm: add modifiers for MediaTek tiled formats

On 18/12/2024 10.33, Daniel Stone wrote:

>> +/* MediaTek layouts */
>> +
>> +/*
>> + * MediaTek Tiled Modifier
>> + * This is a tiled layout using tiles of 16x32 pixels in a row-major layout.
>> + * For chroma planes this becomes 16x16 tiles.
>> + */
>> +#define DRM_FORMAT_MOD_MTK_16L_32S_TILE  fourcc_mod_code(MTK, (1ULL << 0))
> I think this probably wants to be something like the tiling mode
> defined in AMD/Arm modifiers, i.e. reserve a few bits in the range to
> select the tile size, rather than using a single bit here.

Thank you for taking the time, and for your suggestions. Are you 
thinking something along the lines of:

/* MediaTek modifiers
  * Bits  Parameter                Notes
  * ----- ------------------------ 
---------------------------------------------
  *   3:0 TILE LAYOUT              Values are MTK_FMT_MOD_TILE_*
  *   7:4 COMPRESSION              Values are MTK_FMT_MOD_COMPRESS_*
  *  12:8 10 BIT LAYOUT            Values are MTK_FMT_MOD_10BIT_LAYOUT_*
  *
  */

#define DRM_FORMAT_MOD_MTK(__flags)        fourcc_mod_code(MTK, __flags)

/*
  * MediaTek Tiled Modifier
  * The lowest 4 bits of the modifier is used to specify the tiling
  * layout. Only the 16L_32S tiling is used for now, but we define an
  * "untiled" version and leave room for future expansion.
  */
#define MTK_FMT_MOD_TILE_MASK     0xf
#define MTK_FMT_MOD_TILE_NONE     0x0
#define MTK_FMT_MOD_TILE_16L32S   0x1

/*
  * Bits 4-7 specify compression options
  */
#define MTK_FMT_MOD_COMPRESS_MASK (0xf << 4)
#define MTK_FMT_MOD_COMPRESS_NONE (0x0 << 4)
#define MTK_FMT_MOD_COMPRESS_V1   (0x1 << 4)

/*
  * Bits 8-11 specify how the bits of 10 bit formats are
  * stored out in memory
  */
#define MTK_FMT_MOD_10BIT_LAYOUT_MASK      (0xf << 8)
#define MTK_FMT_MOD_10BIT_LAYOUT_PACKED    (0x0 << 8)
#define MTK_FMT_MOD_10BIT_LAYOUT_LSBTILED  (0x1 << 8)
#define MTK_FMT_MOD_10BIT_LAYOUT_LSBRASTER (0x2 << 8)

Regards,

Eric