Hi Himanshu, On 30/09/2025 06:03, Himanshu Dewangan wrote: > Exynos MFC new driver upstream proposal > +++++++++++++++++++++++++++++++++++++++ > > The s5p-mfc driver in the kernel is quite outdated and has not kept up with > the hardware advances of the MFC IP. > Going forward, we want to provide support for all the later versions of MFC > in open source (both mobile and > ExynosAuto would be supported by Samsung) > > We (Samsung) would like to propose a new driver for the latest generation of > Samsung MFC (Multi-Format Codec) hardware. > Although the kernel already contains a Samsung MFC driver > (drivers/media/platform/s5p-mfc/), the newer hardware > diverges significantly from the previous generations, in features supported, > register interface and in system integration. > This has necessitated a new driver, rather than updating the existing one.
I did some (admittedly limited) comparison between the MFC hardware registers in patch 04/29 and what is in s5p-mfc and it did look like an incremental update, not a complete register redesign. So I am not convinced from that that a new driver is needed. In addition, a huge patch bomb like this is unreviewable and so I am just going to give a few high-level remarks based on a quick scan of the patches. 1) Clearly you never ran v4l2-compliance with this new driver as it would fail immediately on the VIDIOC_QUERYCAP ioctl. It's a M2M device, so it should use either V4L2_CAP_VIDEO_M2M or V4L2_CAP_VIDEO_M2M_MPLANE, not a mix of output and capture caps. I suspect that v4l2-compliance will fail on many issues. 2) I noticed that there is no VB2_MMAP support. No idea why not, and all drivers with streaming I/O support must support VB2_MMAP. 3) Lots of controls are added, none of them documented or even defined in a public header. It's part of the public API, so that must all be present in include/uapi/linux. Just 'git grep' for CID_MPEG_MFC51 to see how it should be done. I suspect that more than a few of these controls are either duplicated of already existing controls or should be promoted from MFC-specific controls to generic controls. But without documentation we can't tell. 4) Since this is a new M2M driver I would expect it to use the v4l2-mem2mem framework, instead it appears to be all homegrown. The only reason the existing s5p-mfc driver doesn't use that framework is because it predates it. 5) It clearly doesn't follow the stateful encoder/decoder interface spec as detailed in the V4L2 spec: https://linuxtv.org/downloads/v4l-dvb-apis-new/userspace-api/v4l/dev-mem2mem.html Even s5p-mfc does at least attempt to follow that (I'm not sure how complete support is, given that it's an old driver, but it tries). 6) Minor issue: don't set the .wait_prepare/finish vb2_ops callbacks: these callbacks are slated for removal. Instead set the vb2_queue lock field to the mutex &dev->mfc_mutex. There are probably many other things that need addressing, but I stopped there. I would need convincing (and based on his reply, Krzysztof as well) that a new driver is the right approach. If it is, then start small: just the decoder supporting just one codec. Exclude all the fancy features, just start with the basics. The recently merged Qualcomm iris driver can serve as inspiration: drivers/media/platform/qcom/iris/ I'll mark this series as Rejected in patchwork. It's always a very bad idea to try to upstream a huge driver with zillions of features. If, like this one, it has serious design issues, then you did a lot of work for nothing :-( Apologies for the bad news, Regards, Hans > > > Current driver vs targetted driver comparison > +++++++++++++++++++++++++++++++++++++++++++++ > > Target Feature > Current mainline : Simple V4L2/ VB2 interface based encoder/ decoder > New proposed driver: Dual core support, NAL-q support, LLC, Coredump, > performance > measurement, plugin driver architecture, hardware manager(meerkat), DRM/OTF, > Resource manager, bandwidth compression, New Pixel formats (NV12N, YV12, > P010, > SBWC, RGB family), 10 bit support, HDR support, Prio and RR Process > Scheduler support, > > Register map > Current mainline : Fixed register layout, compatible across s5p variants > New proposed driver: Completely redesigned register set, incompatible with > old layout > > Command model > Current mainline : Mailbox-style command queue > New proposed driver: Ring-buffer command queue with different signaling > > Memory management > Current mainline : CMA-backed contiguous buffers, ION legacy > New proposed driver: dma-heap / scatter-gather buffers with strict alignment > rules > > Firmware > Current mainline : Supports up to Firmware v12, Legacy binary format, loaded > via shared mechanism > New proposed driver: New firmware format, different protocol for control > messages. Support Firmware v13 onwards > > DT bindings > Current mainline : Single clock + reset, simple PM > New proposed driver: Multiple clocks, reset domains, runtime PM dependencies > > Error handling > Current mainline : Simple IRQ error flags > New proposed driver: Detailed error codes, recovery sequences required > > Code impact > Current mainline :~8k LOC, minimal conditionals > New proposed driver: ~65KLOC with full features > > > Plan for supporting latest MFC (Best balance between code clarity and > long-term kernel health, while still respecting ABI and legacy users.) > 1 We propose a new driver (exynos-mfc) for the latest generation of > Samsung MFC (Multi-Format Codec) hardware. > 2 MFC FW V6 to V12 will be supported by existing mainline (s5p-mfc) and > later versions by Exynos-mfc driver > 3 The existing MFC driver will remain available for older SoC’s and will > not be broken. The new driver will only bind > to new compatible strings in DT, avoiding regressions for legacy > hardware. Samsung will take responsibility for > maintaining both drivers until the old one can be formally marked as > “legacy.” > 4 Keep it buildable for old SoCs but clearly say new SoCs should use the > new driver. > 5 VIDEO_SAMSUNG_S5P_MFC and VIDEO_EXYNOS_MFC will both be supported for > an agreed time > 6 Long term Support for new driver - commitment from Samsung > 7 The hardware has diverged to the point where conditionally supporting > both in one codebase is worse for long-term kernel health > 8 Splitting keeps the code clean, testable, and reviewable, while > ensuring legacy users aren’t broken due to user space ABI guarantees. > This seems more clean and easier approach Both can coexist without code > spaghetti. > > Features and description supported > ++++++++++++++++++++++++++++++++++ > > 1 MFC driver registration Probe functionality and video nodes registration > 2 MFC driver open & close support MFC firmware loading, "ls" & "cat" on > the video nodes and udev rules on the video nodes > 3 H264 decoding H264 decoding support - HW supported profiles & levels > (YUV420 Semi-Planar, 8-bit, min/max resolution) > 4 HEVC decoding HEVC decoding support - HW supported profiles & levels > (YUV420 Semi-Planar, 8-bit, min/max resolution) > 5 VP8 decoding VP8 decoding support - HW supported profiles & levels > (YUV420 Semi-Planar, 8-bit, min/max resolution) > 6 VP9 decoding VP9 decoding support - HW supported profiles & levels > (YUV420 Semi-Planar, 8-bit, min/max resolution) > 7 AV1 decoding AV1 decoding support - HW supported profiles & levels > (YUV420 Semi-Planar, 8-bit, min/max resolution) > 8 H264 encoding H264 encoding support - Basic encoding (YUV420 > Semi-Planar, 8-bit, min/max resolution) > 9 HEVC encoding HEVC encoding support - Basic encoding (YUV420 > Semi-Planar, 8-bit, min/max resolution) > 10 VP8 encoding VP8 encoding support - Basic encoding (YUV420 > Semi-Planar, 8-bit, min/max resolution) > 11 VP9 encoding VP9 encoding support - Basic encoding (YUV420 > Semi-Planar, 8-bit, min/max resolution) > 12 Debug fs support Debug fs to control the MFC > functionalities > 13 Debug log support Debug logs to get on the dmesg prompt > for debug purpose > 14 Debug SFR dump support MFC SFR dumps during failures > 15 NAL Queue mode control NAL Queue mode support > 16 Batch mode control Batch mode support > 17 HW supported YUV formats YUV 420, 422, 444 (planar, semi-planar) > formats support as per MFC HW specification > 18 HW supported RGB formats RGB format support as per MFC HW > specification > 19 Multi instance decoding/encoding Multi instance decoding/encoding > 20 Suspend and resume Suspend and resume support > 21 Runtime suspend and resume Runtime suspend and resume support > 22 Priority decoding (decoders) Priority decoding support > 23 Frame delay configuration (decoders) Frame delay configuration > support > 24 Error handling and conceal control (decoders) HW/Platform limitations > should be gracefully exited and, > bit stream errors > should be reported or concealed with warning indication > 25 Reference frame control (encoders) Reference frame control support > 26 SPS/PPS control (encoders) SPS/PPS control support > 27 Loop filter control (encoders) Loop filter control support > 28 B frame support (encoders) B frame support > 29 GOP control (encoders) GOP control support > 30 Frame rate control (encoders) Frame rate control support > > Features to be supported in 2026 > +++++++++++++++++++++++++++++++++ > > 31 Bit rate control (encoders) Bit rate control support > 32 QP control (encoders) QP control support > 33 I/IDR control (encoders) I/IDR control support > 34 Scalable control (encoders) Scalable control support > 35 ROI control (encoders) ROI control support > 36 Multi slice control (encoders) Multi slice control support > 37 Profile/Level control (encoders) Profile/Level control support > 38 Padding control (encoders) Padding control support > 39 Aspect ratio control (encoders) Aspect ratio control support > 40 Buffer full handling (encoders) Buffer full handling support > 41 SBWC SBWC bandwidth compression > support > 42 10-bit support 10-bit support as per MFC HW > specification > 43 Secure signed FW support Security signed FW support > 44 Secure playback DRM content playback for > decoders > 45 HDR Support (decoders) HDR metadata support > 46 Dynamic resolution change Dynamic resolution change > support > > Nagaraju Siddineni (29): > dt-bindings: media: mfc: Add Exynos MFC devicetree binding > arm64: dts: mfc: Add MFC device tree for Auto V920 SoC > media: mfc: Add MFC driver data structures and debugging macros > media: mfc: Add full register map and bit definitions for MFC hardware > media: mfc: Add MFC driver header files and core utilities > media: mfc: Add MFC core hardware register and debugfs APIs > media: mfc: Add MFC core command, hwlock, ISR and run functionalities > media: mfc: Add Exynos‑MFC driver probe support > media: mfc: Add bus‑devfreq, QoS, multi‑view and control > infrastructure > media: mfc: Add buffer‑queue and IOVMM support > media: mfc: Add rate‑calculation framework and memory utilities > media: mfc: Introduce QoS support and instance context handling > media: mfc: Add decoder core sync functions > media: mfc: Add buffer‑control framework > media: mfc: Add decoder resource‑management (RM) support and > load‑balancing > media: mfc: Enhance HW‑lock handling, scheduling and error recovery > media: mfc: Add VB2 decoder support > media: mfc: Add V4L2 decoder driver > media: mfc: Add QoS, Butler workqueue, and priority‑based scheduling > media: mfc: Add H264 decoder support > media: mfc: Add multi‑codec support & QoS improvements > media: mfc: Add H.264 encoder support with buffer and QoS improvements > media: mfc: Add encoder parameters, ROI & QoS support > media: mfc: Add encoder VB2 support to driver > media: mfc: Add encoder v4l2 driver interface > media: mfc: Add full encoder support > media: mfc: Add H.264 encoder support > media: mfc: Add AVC, VP8, VP9, and HEVC encoding support > media: mfc: Hardware‑accelerated encoding support > > .../bindings/media/samsung,exynos-mfc.yaml | 77 + > MAINTAINERS | 10 + > .../dts/exynos/exynosautov920-evt2-mfc.dtsi | 630 +++ > .../arm64/boot/dts/exynos/exynosautov920.dtsi | 1 + > drivers/media/platform/samsung/Kconfig | 7 + > drivers/media/platform/samsung/Makefile | 1 + > .../media/platform/samsung/exynos-mfc/Kconfig | 34 + > .../platform/samsung/exynos-mfc/Makefile | 26 + > .../samsung/exynos-mfc/base/mfc_buf.c | 765 +++ > .../samsung/exynos-mfc/base/mfc_buf.h | 43 + > .../samsung/exynos-mfc/base/mfc_common.h | 444 ++ > .../samsung/exynos-mfc/base/mfc_data_struct.h | 2014 +++++++ > .../samsung/exynos-mfc/base/mfc_debug.h | 247 + > .../samsung/exynos-mfc/base/mfc_format.h | 316 ++ > .../samsung/exynos-mfc/base/mfc_macros.h | 95 + > .../samsung/exynos-mfc/base/mfc_media.h | 554 ++ > .../samsung/exynos-mfc/base/mfc_mem.c | 995 ++++ > .../samsung/exynos-mfc/base/mfc_mem.h | 155 + > .../samsung/exynos-mfc/base/mfc_qos.c | 1070 ++++ > .../samsung/exynos-mfc/base/mfc_qos.h | 99 + > .../samsung/exynos-mfc/base/mfc_queue.c | 966 ++++ > .../samsung/exynos-mfc/base/mfc_queue.h | 158 + > .../exynos-mfc/base/mfc_rate_calculate.c | 640 +++ > .../exynos-mfc/base/mfc_rate_calculate.h | 106 + > .../samsung/exynos-mfc/base/mfc_regs.h | 58 + > .../samsung/exynos-mfc/base/mfc_regs_mfc.h | 1002 ++++ > .../samsung/exynos-mfc/base/mfc_sched.h | 30 + > .../samsung/exynos-mfc/base/mfc_utils.c | 401 ++ > .../samsung/exynos-mfc/base/mfc_utils.h | 481 ++ > .../media/platform/samsung/exynos-mfc/mfc.c | 1366 +++++ > .../platform/samsung/exynos-mfc/mfc_core.c | 703 +++ > .../samsung/exynos-mfc/mfc_core_buf_ctrl.c | 543 ++ > .../samsung/exynos-mfc/mfc_core_cmd.c | 576 ++ > .../samsung/exynos-mfc/mfc_core_cmd.h | 41 + > .../samsung/exynos-mfc/mfc_core_enc_param.c | 1463 ++++++ > .../samsung/exynos-mfc/mfc_core_enc_param.h | 23 + > .../samsung/exynos-mfc/mfc_core_hw_reg_api.c | 122 + > .../samsung/exynos-mfc/mfc_core_hw_reg_api.h | 144 + > .../samsung/exynos-mfc/mfc_core_hwlock.c | 761 +++ > .../samsung/exynos-mfc/mfc_core_hwlock.h | 80 + > .../samsung/exynos-mfc/mfc_core_intlock.c | 98 + > .../samsung/exynos-mfc/mfc_core_intlock.h | 20 + > .../samsung/exynos-mfc/mfc_core_isr.c | 2104 ++++++++ > .../samsung/exynos-mfc/mfc_core_isr.h | 25 + > .../samsung/exynos-mfc/mfc_core_ops.c | 813 +++ > .../samsung/exynos-mfc/mfc_core_ops.h | 16 + > .../platform/samsung/exynos-mfc/mfc_core_pm.c | 209 + > .../platform/samsung/exynos-mfc/mfc_core_pm.h | 33 + > .../samsung/exynos-mfc/mfc_core_reg_api.c | 597 +++ > .../samsung/exynos-mfc/mfc_core_reg_api.h | 380 ++ > .../samsung/exynos-mfc/mfc_core_run.c | 541 ++ > .../samsung/exynos-mfc/mfc_core_run.h | 35 + > .../samsung/exynos-mfc/mfc_core_sched_prio.c | 431 ++ > .../samsung/exynos-mfc/mfc_core_sync.c | 423 ++ > .../samsung/exynos-mfc/mfc_core_sync.h | 34 + > .../samsung/exynos-mfc/mfc_ctx_ctrl.c | 1469 ++++++ > .../platform/samsung/exynos-mfc/mfc_debugfs.c | 248 + > .../platform/samsung/exynos-mfc/mfc_debugfs.h | 20 + > .../samsung/exynos-mfc/mfc_dec_v4l2.c | 1739 +++++++ > .../samsung/exynos-mfc/mfc_dec_v4l2.h | 20 + > .../platform/samsung/exynos-mfc/mfc_dec_vb2.c | 394 ++ > .../platform/samsung/exynos-mfc/mfc_dec_vb2.h | 19 + > .../samsung/exynos-mfc/mfc_enc_v4l2.c | 4614 +++++++++++++++++ > .../samsung/exynos-mfc/mfc_enc_v4l2.h | 20 + > .../platform/samsung/exynos-mfc/mfc_enc_vb2.c | 443 ++ > .../platform/samsung/exynos-mfc/mfc_enc_vb2.h | 19 + > .../platform/samsung/exynos-mfc/mfc_rm.c | 2652 ++++++++++ > .../platform/samsung/exynos-mfc/mfc_rm.h | 110 + > 68 files changed, 34773 insertions(+) > create mode 100644 > Documentation/devicetree/bindings/media/samsung,exynos-mfc.yaml > create mode 100644 arch/arm64/boot/dts/exynos/exynosautov920-evt2-mfc.dtsi > create mode 100644 drivers/media/platform/samsung/exynos-mfc/Kconfig > create mode 100644 drivers/media/platform/samsung/exynos-mfc/Makefile > create mode 100644 drivers/media/platform/samsung/exynos-mfc/base/mfc_buf.c > create mode 100644 drivers/media/platform/samsung/exynos-mfc/base/mfc_buf.h > create mode 100644 > drivers/media/platform/samsung/exynos-mfc/base/mfc_common.h > create mode 100644 > drivers/media/platform/samsung/exynos-mfc/base/mfc_data_struct.h > create mode 100644 drivers/media/platform/samsung/exynos-mfc/base/mfc_debug.h > create mode 100644 > drivers/media/platform/samsung/exynos-mfc/base/mfc_format.h > create mode 100644 > drivers/media/platform/samsung/exynos-mfc/base/mfc_macros.h > create mode 100644 drivers/media/platform/samsung/exynos-mfc/base/mfc_media.h > create mode 100644 drivers/media/platform/samsung/exynos-mfc/base/mfc_mem.c > create mode 100644 drivers/media/platform/samsung/exynos-mfc/base/mfc_mem.h > create mode 100644 drivers/media/platform/samsung/exynos-mfc/base/mfc_qos.c > create mode 100644 drivers/media/platform/samsung/exynos-mfc/base/mfc_qos.h > create mode 100644 drivers/media/platform/samsung/exynos-mfc/base/mfc_queue.c > create mode 100644 drivers/media/platform/samsung/exynos-mfc/base/mfc_queue.h > create mode 100644 > drivers/media/platform/samsung/exynos-mfc/base/mfc_rate_calculate.c > create mode 100644 > drivers/media/platform/samsung/exynos-mfc/base/mfc_rate_calculate.h > create mode 100644 drivers/media/platform/samsung/exynos-mfc/base/mfc_regs.h > create mode 100644 > drivers/media/platform/samsung/exynos-mfc/base/mfc_regs_mfc.h > create mode 100644 drivers/media/platform/samsung/exynos-mfc/base/mfc_sched.h > create mode 100644 drivers/media/platform/samsung/exynos-mfc/base/mfc_utils.c > create mode 100644 drivers/media/platform/samsung/exynos-mfc/base/mfc_utils.h > create mode 100644 drivers/media/platform/samsung/exynos-mfc/mfc.c > create mode 100644 drivers/media/platform/samsung/exynos-mfc/mfc_core.c > create mode 100644 > drivers/media/platform/samsung/exynos-mfc/mfc_core_buf_ctrl.c > create mode 100644 drivers/media/platform/samsung/exynos-mfc/mfc_core_cmd.c > create mode 100644 drivers/media/platform/samsung/exynos-mfc/mfc_core_cmd.h > create mode 100644 > drivers/media/platform/samsung/exynos-mfc/mfc_core_enc_param.c > create mode 100644 > drivers/media/platform/samsung/exynos-mfc/mfc_core_enc_param.h > create mode 100644 > drivers/media/platform/samsung/exynos-mfc/mfc_core_hw_reg_api.c > create mode 100644 > drivers/media/platform/samsung/exynos-mfc/mfc_core_hw_reg_api.h > create mode 100644 > drivers/media/platform/samsung/exynos-mfc/mfc_core_hwlock.c > create mode 100644 > drivers/media/platform/samsung/exynos-mfc/mfc_core_hwlock.h > create mode 100644 > drivers/media/platform/samsung/exynos-mfc/mfc_core_intlock.c > create mode 100644 > drivers/media/platform/samsung/exynos-mfc/mfc_core_intlock.h > create mode 100644 drivers/media/platform/samsung/exynos-mfc/mfc_core_isr.c > create mode 100644 drivers/media/platform/samsung/exynos-mfc/mfc_core_isr.h > create mode 100644 drivers/media/platform/samsung/exynos-mfc/mfc_core_ops.c > create mode 100644 drivers/media/platform/samsung/exynos-mfc/mfc_core_ops.h > create mode 100644 drivers/media/platform/samsung/exynos-mfc/mfc_core_pm.c > create mode 100644 drivers/media/platform/samsung/exynos-mfc/mfc_core_pm.h > create mode 100644 > drivers/media/platform/samsung/exynos-mfc/mfc_core_reg_api.c > create mode 100644 > drivers/media/platform/samsung/exynos-mfc/mfc_core_reg_api.h > create mode 100644 drivers/media/platform/samsung/exynos-mfc/mfc_core_run.c > create mode 100644 drivers/media/platform/samsung/exynos-mfc/mfc_core_run.h > create mode 100644 > drivers/media/platform/samsung/exynos-mfc/mfc_core_sched_prio.c > create mode 100644 drivers/media/platform/samsung/exynos-mfc/mfc_core_sync.c > create mode 100644 drivers/media/platform/samsung/exynos-mfc/mfc_core_sync.h > create mode 100644 drivers/media/platform/samsung/exynos-mfc/mfc_ctx_ctrl.c > create mode 100644 drivers/media/platform/samsung/exynos-mfc/mfc_debugfs.c > create mode 100644 drivers/media/platform/samsung/exynos-mfc/mfc_debugfs.h > create mode 100644 drivers/media/platform/samsung/exynos-mfc/mfc_dec_v4l2.c > create mode 100644 drivers/media/platform/samsung/exynos-mfc/mfc_dec_v4l2.h > create mode 100644 drivers/media/platform/samsung/exynos-mfc/mfc_dec_vb2.c > create mode 100644 drivers/media/platform/samsung/exynos-mfc/mfc_dec_vb2.h > create mode 100644 drivers/media/platform/samsung/exynos-mfc/mfc_enc_v4l2.c > create mode 100644 drivers/media/platform/samsung/exynos-mfc/mfc_enc_v4l2.h > create mode 100644 drivers/media/platform/samsung/exynos-mfc/mfc_enc_vb2.c > create mode 100644 drivers/media/platform/samsung/exynos-mfc/mfc_enc_vb2.h > create mode 100644 drivers/media/platform/samsung/exynos-mfc/mfc_rm.c > create mode 100644 drivers/media/platform/samsung/exynos-mfc/mfc_rm.h >
