video: rockchip: rga3: fix compatibility with legacy global alpha config

[nyanmisaka]

Fixes a RGA regression in rkr6 7291693, which broke compatibility with librga 1.9.x and older when using DST over blend/composite and premultiplied alpha.

It's a typo.

req->alpha_config.bg_global_alpha_value = 0xff; // should be `fg` foreground instead of `bg` background
req->alpha_config.bg_global_alpha_value = 0xff; // duplicated

When req_rga->feature.global_alpha_en is false, it means the API version of userspace librga is 1.9.x and older. And this fix is to make sure it falls back to the legacy behavior.

In addition, the source code of librga 1.10 is not yet available to the public at this point.

[amazingfate]

Another rga3 related issue: gstreamer videoconvert can't use RGA3 to convert hdmiin. Here is the pipeline command line I use:

GST_VIDEO_CONVERT_USE_RGA=1 gst-launch-1.0 -e v4l2src device=/dev/video0 ! videoconvert ! waylandsink

After reverting fb4fd88 this pipeline will work again. But I haven't found the root cause.

[nyanmisaka]

Another rga3 related issue: gstreamer videoconvert can't use RGA3 to convert hdmiin. Here is the pipeline command line I use:

GST_VIDEO_CONVERT_USE_RGA=1 gst-launch-1.0 -e v4l2src device=/dev/video0 ! videoconvert ! waylandsink

After reverting fb4fd88 this pipeline will work again. But I haven't found the root cause.

It seems to be related to the use of virt_addr, I don't use it in my FFmpeg build and use dma_fd instead, so I don't encounter this problem. Maybe the maintainer of gstreamer plugin @JeffyCN knows more.