media: allegro: Annotate struct mcu_msg_push_buffers_internal with __counted_by

Prepare for the coming implementation by GCC and Clang of the __counted_by
attribute. Flexible array members annotated with __counted_by can have
their accesses bounds-checked at run-time checking via CONFIG_UBSAN_BOUNDS
(for array indexing) and CONFIG_FORTIFY_SOURCE (for strcpy/memcpy-family
functions).

As found with Coccinelle[1], add __counted_by for
struct mcu_msg_push_buffers_internal.

[1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci

Cc: Michael Tretter <m.tretter@pengutronix.de>
Cc: Pengutronix Kernel Team <kernel@pengutronix.de>
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>

media: allegro: add encoder buffer support

The encoder buffer serves as a cache for reference frames during the
encoding process. The encoder buffer significantly reduces the bandwidth
requirement for read accesses on the AXI ports of the VCU, but slightly
reduces the quality of the encoded video.

The encoder buffer must be configured as a whole during the firmware
initialization and later explicitly enabled for every channel that shall
use the encoder buffer.

Prior to firmware version 2019.2, it was necessary to explicitly set the
size of the encoder buffer for every channel. Since 2019.2 it is
sufficient to enable the encoder buffer and leave the rest to the
firmware. Therefore, only support the encoder buffer for firmware 2019.2
and later.

Signed-off-by: Michael Tretter <m.tretter@pengutronix.de>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

media: allegro: add support for HEVC encoding

The Allegro Codec supports HEVC encoding. The messages to the MCU are
the same for H.264 and HEVC, but some options have to be changed. These
are actually only a few options.

The driver, however, must add the HEVC VPS/SPS/PPS NAL Units to the
coded stream and must properly provide the HEVC format and controls to
user space.

[hverkuil: fix warning for wrong enum type (h264 instead of hevc)]

Signed-off-by: Michael Tretter <m.tretter@pengutronix.de>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

media: allegro: rename stream_id to dst_handle

The dst_handle field in the PUT_STREAM_BUFFER and ENCODE_FRAME_RESPONSE
is used to retrieve the V4L2 CAPTURE buffer. Calling it stream_id is
confusing. Call it dst_handle inspired by src_handle for the OUTPUT
buffer.

Signed-off-by: Michael Tretter <m.tretter@pengutronix.de>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

media: allegro: move driver out of staging

The stateful encoder API was finalized. Nothing is blocking the driver
from being moved out of staging.

Signed-off-by: Michael Tretter <m.tretter@pengutronix.de>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>