Message-ID: <ed7a463e-9654-41c3-91f6-f3f877fd9a20@imgtec.com>
Date: Fri, 31 Jan 2025 15:39:17 +0000
From: Matt Coster <Matt.Coster@...tec.com>
To: Michal Wilczynski <m.wilczynski@...sung.com>,
        "mturquette@...libre.com"
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        Frank Binns
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CC: "linux-clk@...r.kernel.org" <linux-clk@...r.kernel.org>,
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Subject: Re: [PATCH v4 00/18] Enable drm/imagination BXM-4-64 Support for
 LicheePi 4A

On 28/01/2025 19:47, Michal Wilczynski wrote:
> The LicheePi 4A board, featuring the T-HEAD TH1520 SoC, includes an Imagination
> Technologies BXM-4-64 GPU. Initial support for this GPU was provided through a
> downstream driver [1]. Recently, efforts have been made to upstream support for
> the Rogue family GPUs, which the BXM-4-64 is part of [2].
> 
> While the initial upstream driver focused on the AXE-1-16 GPU, newer patches
> have introduced support for the BXS-4-64 GPU [3]. The modern upstream
> drm/imagination driver is expected to support the BXM-4-64 as well [4][5]. As
> this support is being developed, it's crucial to upstream the necessary glue
> code including clock and power-domain drivers so they're ready for integration
> with the drm/imagination driver.
> 
> Recent Progress:
> 
> Firmware Improvements:
> Since August, the vendor has provided updated firmware
> [6][7] that correctly initiates the firmware for the BXM-4-64.
> 
> Mesa Driver Testing:
> The vendor-supplied Mesa driver [8] partially works with Vulkan examples, such
> as rendering a triangle using Sascha Willems' Vulkan samples [9]. Although the
> triangle isn't rendered correctly (only the blue background appears), shader
> job submissions function properly, and IOCTL calls are correctly invoked.  For
> testing, we used the following resources:
> 
> Kernel Source: Custom kernel with necessary modifications [10].
> Mesa Driver: Vendor-provided Mesa implementation [11].
> 
> Dependencies:
> Testing required a functional Display Processing Unit (DPU) and HDMI driver,
> which are currently not upstreamed. Efforts are underway to upstream the DPU
> DC8200 driver used in StarFive boards [12], which is the same DPU used on the
> LicheePi 4A. Once the DPU and HDMI drivers are upstreamed, GPU support can be
> fully upstream.
> 
> Testing Status:
> This series has been tested by performing a probe-only operation, confirming
> that the firmware begins execution. The probe function initiates firmware
> execution and waits for the firmware to flip a specific status bit.
> 
> [   12.637880] powervr ffef400000.gpu: [drm] loaded firmware powervr/rogue_36.52.104.182_v1.fw
> [   12.648979] powervr ffef400000.gpu: [drm] FW version v1.0 (build 6645434 OS)
> [   12.678906] [drm] Initialized powervr 1.0.0 for ffef400000.gpu on minor 0
> 
> Power Management:
> Full power management capabilities require implementing the T-HEAD SoC AON
> protocol messaging via the hardware mailbox. Support for the mailbox was merged
> in kernel 6.13 [13], and the AON protocol implementation is part of this
> series, since v2. Therefore this series support full power management
> capabilities for the GPU driver.
> 
> Thanks everyone for taking the time to review the last revision ! Your
> guidance and the direction was very helpful.

Hi Michal,

This is awesome, thanks for contributing! I apologise for not responding
to earlier versions (things have been pretty busy here), but they have
very much been on my radar.

I see you're already aware of my other B-Series patchs[3]; would you
mind rebasing these changes on top of those? We're making some not
insignificant changes to the bindings which will conflict with any new
GPUs added in the meantime. I'll leave comments in this series where I
suspect the conflicts will appear.

Cheers,
Matt

> Since this patchset is slowly getting closer to being ready I'm dropping the
> RFC prefix with the v4.
> 
> v4:
> 
> Device Tree Changes:
> - restructured power device tree bindings by abstracting power-domain IDs from
>   firmware IDs, with the mappings now defined in a dedicated header file
> - retained existing clock-names in img,powervr-rogue.yaml to maintain ABI
>   compatibility, despite having only one downstream user
> - enhanced documentation for new Video Output (VO) clock inputs in device tree
>   bindings
> 
> Reset Driver Changes:
> - reverted reset-cells configuration to single cell as in v2
> - maintained reset definitions in device tree bindings while deferring
>   implementation of watchdog timer (WDT) reset functionality
> - addressed implementation issues in the DRM/Imagination reset driver
> 
> Power Domain Changes:
> - added workaround to disable AUDIO power domain to prevent firmware crashes
> 
> v3:
> 
> Device Tree Changes:
>  - consolidated device tree representation by merging aon and power-domain nodes
>    while maintaining separate drivers internally
>  - power-domain driver is now instantiated from within the aon driver
>  - updated img,powervr-rogue.yaml to use allOf and oneOf for better schema
>    organization
> 
> AP Clock Driver Improvements:
>  - reworked driver to support multiple clock controllers through .compatible
>    and .data instead of using multiple address spaces in dt-binding. This change
>    allows to re-use the driver code for multiple clock controllers
> 
> Code Quality and Documentation:
>  - fixed optional module dependencies in Kconfig
>  - added kernel-doc comments for all exported functions
>  - implemented th1520_aon_remove() to properly clean up mailbox channel
>    resources
>  - removed unnecessary of.h header in multiple drivers
>  - refactored reset driver to use zero cells
> 
> v2:
> 
> Removed AP_SUBSYS clock refactoring commits (1-6):
>  - instead of refactoring, I opted to extend the current driver and its
>    associated device tree node to include support for a second address space.
> 
> Expanded patchset scope to fully support power management capabilities:
>  - introduced a new firmware driver to manage power-related operations.
>  - rewrote the power-domain driver to function alongside the firmware driver.
>    These nodes in the device tree lack direct address spaces, despite
>    representing HW blocks. Control is achieved via firmware protocol messages
>    transmitted through a mailbox to the E902 core.
> 
> Implemented a reset controller for the TH1520 SoC:
>  - developed a reset controller driver for the TH1520 to manage reset
>    sequences.
>  - updated the drm/imagination driver to act as a reset controller consumer.
>    While this patchset is focused on the LPI4A board, the reset controller is
>    designed to be useful for other boards, such as the BPI-3F, which also require
>    a reset sequence after power-up.
> 
> Updated dt-bindings:
>  - added new dt-bindings for power, reset, and firmware nodes.
>  - updated the powervr dt-binding to include reset support and new compatibles.
>  - ran dtbs_check and dt_binding_check to ensure compliance.
> 
> Addressed code quality:
>  - resolved all checkpatch issues using --strict, except for the call to
>    devm_clk_hw_register_gate_parent_data().  The current implementation remains
>    preferable in this context, and clang-format aligns with this choice.
> 
> References:
> 
> [1] Downstream Driver Source:
>     https://gitlab.freedesktop.org/frankbinns/powervr/-/blob/cb1929932095649a24f051b9cfdd2cd2ceab35cb/drivers/gpu/drm/img-rogue/Kconfig
> 
> [2] Initial Upstream Driver Series:
>     https://lore.kernel.org/all/cover.1700668843.git.donald.robson@imgtec.com/
> 
> [3] BXS-4-64 GPU Support Patches:
>     https://lore.kernel.org/all/20241105-sets-bxs-4-64-patch-v1-v1-0-4ed30e865892@imgtec.com/
> 
> [4] Firmware Issue Discussion 1:
>     https://gitlab.freedesktop.org/imagination/linux-firmware/-/issues/1
> 
> [5] Firmware Issue Discussion 2:
>     https://gitlab.freedesktop.org/imagination/linux-firmware/-/issues/2
> 
> [6] Firmware Update Commit 1:
>     https://gitlab.freedesktop.org/imagination/linux-firmware/-/commit/6ac2247e9a1d1837af495fb6d0fbd6f35547c2d1
> 
> [7] Firmware Update Commit 2:
>     https://gitlab.freedesktop.org/imagination/linux-firmware/-/commit/efbebc90f25adb2b2e1499e3cc24ea3f3c3e4f4c
> 
> [8] Vendor-Provided Mesa Driver:
>     https://gitlab.freedesktop.org/imagination/mesa/-/tree/dev/devinfo
> 
> [9] Sascha Willems' Vulkan Samples:
>     https://github.com/SaschaWillems/Vulkan
> 
> [10] Test Kernel Source:
>     https://github.com/mwilczy/linux/tree/2_December_reference_linux_kernel_imagination
> 
> [11] Test Mesa Driver:
>     https://github.com/mwilczy/mesa-reference
> 
> [12] DPU DC8200 Driver Upstream Attempt:
>     https://lore.kernel.org/all/20241120061848.196754-1-keith.zhao@starfivetech.com/
> 
> [13] Pull request kernel 6.13 for mailbox
>     https://lore.kernel.org/all/CABb+yY33qnivK-PzqpSMgmtbFid4nS8wcNvP7wED9DXrYAyLKg@mail.gmail.com/
> 
> Michal Wilczynski (18):
>   dt-bindings: clock: thead: Add TH1520 VO clock controller
>   clk: thead: Add clock support for VO subsystem in T-Head TH1520 SoC
>   dt-bindings: firmware: thead,th1520: Add support for firmware node
>   firmware: thead: Add AON firmware protocol driver
>   dt-bindings: power: Add TH1520 SoC power domains
>   pmdomain: thead: Add power-domain driver for TH1520
>   riscv: Enable PM_GENERIC_DOMAINS for T-Head SoCs
>   dt-bindings: reset: Add T-HEAD TH1520 SoC Reset Controller
>   reset: thead: Add TH1520 reset controller driver
>   drm/imagination: Add reset controller support for GPU initialization
>   dt-bindings: gpu: Add 'resets' property for GPU initialization
>   dt-bindings: gpu: Add support for T-HEAD TH1520 GPU
>   drm/imagination: Add support for IMG BXM-4-64 GPU
>   drm/imagination: Enable PowerVR driver for RISC-V
>   riscv: dts: thead: Add device tree VO clock controller
>   riscv: dts: thead: Introduce power domain nodes with aon firmware
>   riscv: dts: thead: Introduce reset controller node
>   riscv: dts: thead: Add GPU node to TH1520 device tree
> 
>  .../bindings/clock/thead,th1520-clk-ap.yaml   |  17 +-
>  .../bindings/firmware/thead,th1520-aon.yaml   |  53 ++++
>  .../bindings/gpu/img,powervr-rogue.yaml       |  42 ++-
>  .../bindings/reset/thead,th1520-reset.yaml    |  44 +++
>  MAINTAINERS                                   |   8 +
>  arch/riscv/Kconfig.socs                       |   1 +
>  arch/riscv/boot/dts/thead/th1520.dtsi         |  34 +++
>  drivers/clk/thead/clk-th1520-ap.c             | 197 +++++++++++--
>  drivers/firmware/Kconfig                      |   9 +
>  drivers/firmware/Makefile                     |   1 +
>  drivers/firmware/thead,th1520-aon.c           | 268 ++++++++++++++++++
>  drivers/gpu/drm/imagination/Kconfig           |   2 +-
>  drivers/gpu/drm/imagination/pvr_device.c      |  21 ++
>  drivers/gpu/drm/imagination/pvr_device.h      |   9 +
>  drivers/gpu/drm/imagination/pvr_drv.c         |   1 +
>  drivers/gpu/drm/imagination/pvr_power.c       |  12 +-
>  drivers/pmdomain/Kconfig                      |   1 +
>  drivers/pmdomain/Makefile                     |   1 +
>  drivers/pmdomain/thead/Kconfig                |  12 +
>  drivers/pmdomain/thead/Makefile               |   2 +
>  drivers/pmdomain/thead/th1520-pm-domains.c    | 193 +++++++++++++
>  drivers/reset/Kconfig                         |  10 +
>  drivers/reset/Makefile                        |   1 +
>  drivers/reset/reset-th1520.c                  | 178 ++++++++++++
>  .../dt-bindings/clock/thead,th1520-clk-ap.h   |  33 +++
>  .../dt-bindings/power/thead,th1520-power.h    |  19 ++
>  .../dt-bindings/reset/thead,th1520-reset.h    |  15 +
>  .../linux/firmware/thead/thead,th1520-aon.h   | 197 +++++++++++++
>  28 files changed, 1344 insertions(+), 37 deletions(-)
>  create mode 100644 Documentation/devicetree/bindings/firmware/thead,th1520-aon.yaml
>  create mode 100644 Documentation/devicetree/bindings/reset/thead,th1520-reset.yaml
>  create mode 100644 drivers/firmware/thead,th1520-aon.c
>  create mode 100644 drivers/pmdomain/thead/Kconfig
>  create mode 100644 drivers/pmdomain/thead/Makefile
>  create mode 100644 drivers/pmdomain/thead/th1520-pm-domains.c
>  create mode 100644 drivers/reset/reset-th1520.c
>  create mode 100644 include/dt-bindings/power/thead,th1520-power.h
>  create mode 100644 include/dt-bindings/reset/thead,th1520-reset.h
>  create mode 100644 include/linux/firmware/thead/thead,th1520-aon.h
> 

-- 
Matt Coster
E: matt.coster@...tec.com


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