Hi Nicolas, On Saturday 15 Jul 2017 12:49:13 Personnel wrote: You might want to fix your mailer to use your name :-) > Le samedi 15 juillet 2017 à 12:42 +0300, Laurent Pinchart a écrit : > > On Saturday 15 Jul 2017 14:58:36 Jacob Chen wrote: > >> Rockchip RGA is a separate 2D raster graphic acceleration unit. It > >> accelerates 2D graphics operations, such as point/line drawing, image > >> scaling, rotation, BitBLT, alpha blending and image blur/sharpness. > >> > >> The drvier is mostly based on s5p-g2d v4l2 m2m driver. > >> And supports various operations from the rendering pipeline. > >> > >> - copy > >> - fast solid color fill > >> - rotation > >> - flip > >> - alpha blending > > > > I notice that you don't support the drawing operations. How do you plan to > > support them later through the V4L2 M2M API ? I hate stating the obvious, > > but wouldn't the DRM API be better fit for a graphic accelerator ? > > It could fit, maybe, but it really lacks some framework. Also, DRM is > not really meant for M2M operation, and it's also not great for multi- > process. GPUs on embedded devices are mem-to-mem, and they're definitely shared between multiple processes :-) > Until recently, there was competing drivers for Exynos, both > implemented in V4L2 and DRM, for similar rational, all DRM ones are > being deprecated/removed. > > I think 2D blitters in V4L2 are fine, but they terribly lack something > to differentiate them from converters/scalers when looking up the HW > list. Could be as simple as a capability flag, if I can suggest. For > the reference, the 2D blitter on IMX6 has been used to implement a live > video mixer in GStreamer. > > https://bugzilla.gnome.org/show_bug.cgi?id=772766 If we decide that 2D blitters should be supported by V4L2 (and I'm open to get convinced about that), we really need to define a proper API before merging a bunch of drivers that will implement things in slightly different ways, otherwise the future will be very painful. Among the issues that need to be solved are - stateful vs. stateless operation (as mentioned by Jacob in this mail thread), a.k.a. the request API - exposing capabilities to userspace (a single capability flag would be enough only if all blitters expose the same API, which I'm not sure we can assume) - single input (a.k.a. in-place blitters as you mentioned below) vs. multiple inputs - API for 2D-accelerated operations other than blitting (filling, point and line drawing, ...) > > Additionally, V4L2 M2M has one source and one destination. How do you > > implement alpha blending in that case, which by definition requires at > > least two sources ? > > This type of HW only do in-place blits. When using such a node, the > buffer queued on the V4L2_CAPTURE contains the destination image, and > the buffer queued on the V4L2_OUTPUT is the source image. > > >> The code in rga-hw.c is used to configure regs accroding to operations. > >> > >> The code in rga-buf.c is used to create private mmu table for RGA. > >> The tables is stored in a list, and be removed when buffer is cleanup. > > > > Looking at the implementation it seems to be a scatter-gather list, not an > > MMU. Is that right ? Does the hardware documentation refer to it as an MMU > > ? > > > >> Signed-off-by: Jacob Chen <jacob-chen@xxxxxxxxxx> > >> --- > >> > >> drivers/media/platform/Kconfig | 11 + > >> drivers/media/platform/Makefile | 2 + > >> drivers/media/platform/rockchip-rga/Makefile | 3 + > >> drivers/media/platform/rockchip-rga/rga-buf.c | 122 ++++ > >> drivers/media/platform/rockchip-rga/rga-hw.c | 652 ++++++++++++++++++ > >> drivers/media/platform/rockchip-rga/rga-hw.h | 437 ++++++++++++ > >> drivers/media/platform/rockchip-rga/rga.c | 958 +++++++++++++++++++ > >> drivers/media/platform/rockchip-rga/rga.h | 111 +++ > >> 8 files changed, 2296 insertions(+) > >> create mode 100644 drivers/media/platform/rockchip-rga/Makefile > >> create mode 100644 drivers/media/platform/rockchip-rga/rga-buf.c > >> create mode 100644 drivers/media/platform/rockchip-rga/rga-hw.c > >> create mode 100644 drivers/media/platform/rockchip-rga/rga-hw.h > >> create mode 100644 drivers/media/platform/rockchip-rga/rga.c > >> create mode 100644 drivers/media/platform/rockchip-rga/rga.h -- Regards, Laurent Pinchart -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
