linux-kernel - [PATCH v4 7/8] drm/fourcc: amlogic: Add modifier definitions for the Scatter layout

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Message-Id: <20200325085025.30631-8-narmstrong@baylibre.com>
Date:   Wed, 25 Mar 2020 09:50:24 +0100
From:   Neil Armstrong <narmstrong@...libre.com>
To:     daniel@...ll.ch, dri-devel@...ts.freedesktop.org
Cc:     ppaalanen@...il.com, mjourdan@...libre.com, brian.starkey@....com,
        Neil Armstrong <narmstrong@...libre.com>,
        linux-amlogic@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Kevin Hilman <khilman@...libre.com>
Subject: [PATCH v4 7/8] drm/fourcc: amlogic: Add modifier definitions for the Scatter layout

Amlogic uses a proprietary lossless image compression protocol and format
for their hardware video codec accelerators, either video decoders or
video input encoders.

This introduces the Scatter Memory layout, means the header contains IOMMU
references to the compressed frames content to optimize memory access
and layout.

In this mode, only the header memory address is needed, thus the content
memory organization is tied to the current producer execution and cannot
be saved/dumped neither transferrable between Amlogic SoCs supporting this
modifier.

Tested-by: Kevin Hilman <khilman@...libre.com>
Signed-off-by: Neil Armstrong <narmstrong@...libre.com>
---
 include/uapi/drm/drm_fourcc.h | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/include/uapi/drm/drm_fourcc.h b/include/uapi/drm/drm_fourcc.h
index 84edc5d69613..b49f1d45e1b4 100644
--- a/include/uapi/drm/drm_fourcc.h
+++ b/include/uapi/drm/drm_fourcc.h
@@ -840,6 +840,19 @@ extern "C" {
  */
 #define DRM_FORMAT_MOD_AMLOGIC_FBC_LAYOUT_BASIC		(1ULL << 0)
 
+/*
+ * Amlogic FBC Scatter Memory layout
+ *
+ * Indicates the header contains IOMMU references to the compressed
+ * frames content to optimize memory access and layout.
+ *
+ * In this mode, only the header memory address is needed, thus the
+ * content memory organization is tied to the current producer
+ * execution and cannot be saved/dumped neither transferrable between
+ * Amlogic SoCs supporting this modifier.
+ */
+#define DRM_FORMAT_MOD_AMLOGIC_FBC_LAYOUT_SCATTER	(2ULL << 0)
+
 /*
  * Amlogic FBC Layout Options
  */
@@ -852,7 +865,8 @@ extern "C" {
  * memory.
  *
  * This mode reduces body layout to 3072 bytes per 64x32 superblock with
- * the basic layout.
+ * the basic layout and 3200 bytes per 64x32 superblock combined with
+ * the scatter layout.
  */
 #define DRM_FORMAT_MOD_AMLOGIC_FBC_MEM_SAVING	(1ULL << 8)
 
-- 
2.22.0