This patchset adds interconnect API support for the Exynos SoC "samsung, exynos-bus" compatible devices, which already have their corresponding exynos-bus driver in the devfreq subsystem. Complementing the devfreq driver with an interconnect functionality allows to ensure the QoS requirements of devices accessing the system memory (e.g. video processing devices) are fulfilled and aallows to avoid issues like the one discussed in thread [1].
This patch series adds implementation of the interconnect provider per each "samsung,exynos-bus" compatible DT node, with one interconnect node per provider. The interconnect code which was previously added as a part of the devfreq driver has been converted to a separate platform driver. In the devfreq a corresponding virtual child platform device is registered. Integration of devfreq and interconnect frameworks is achieved through the PM QoS API.
A sample interconnect consumer for exynos-mixer is added in patches 5/6, 6/6, it is currently added only for exynos4412 and allows to address the mixer DMA underrun error issues [1].
Main changes since v5 [3] is an addition of "bus-width: DT property, which specifies data width of the interconnect bus (patches 1...2/6 and addition of synchronization of the interconnect bandwidth setting with VSYNC (patch 6/6).
The series has been tested on Odroid U3 board. It is based on icc-next branch, which already includes required patches [2]: 26c205e interconnect: Allow inter-provider pairs to be configured 0db4ee05 interconnect: Relax requirement in of_icc_get_from_provider() 6998a7c interconnect: Export of_icc_get_from_provider()
-- Regards, Sylwester
Changes since v3 [4] (v4 skipped to align with patchset [1]), detailed changes are listed in each patch: - conversion to a separate interconnect (platform) driver, - an update of the DT binding documenting new optional properties: #interconnect-cells, samsung,interconnect-parent in "samsung,exynos-bus" nodes, - new DT properties added to the SoC, rather than to the board specific files.
Changes since v2 [5]: - Use icc_std_aggregate(). - Implement a different modification of apply_constraints() in drivers/interconnect/core.c (patch 03). - Use 'exynos,interconnect-parent-node' in the DT instead of 'devfreq'/'parent', depending on the bus. - Rebase on DT patches that deprecate the 'devfreq' DT property. - Improve error handling, including freeing generated IDs on failure. - Remove exynos_bus_icc_connect() and add exynos_bus_icc_get_parent().
Changes since v1 [6]: - Rebase on coupled regulators patches. - Use dev_pm_qos_*() API instead of overriding frequency in exynos_bus_target(). - Use IDR for node ID allocation. - Reverse order of multiplication and division in mixer_set_memory_bandwidth() (patch 07) to avoid integer overflow.
References: [1] https://patchwork.kernel.org/patch/10861757/ (original issue) [2] https://www.spinics.net/lists/linux-samsung-soc/msg70014.html [3] https://www.spinics.net/lists/arm-kernel/msg810722.html [4] https://lore.kernel.org/linux-pm/20191220115653.6487-1-a.swigon@samsung.com [5] https://patchwork.kernel.org/cover/11054417/ (v1 of this RFC) [6] https://patchwork.kernel.org/cover/11152595/ (v2 of this RFC)
Artur Świgoń (1): ARM: dts: exynos: Add interconnects to Exynos4412 mixer
Sylwester Nawrocki (5): dt-bindings: exynos-bus: Add documentation for interconnect properties interconnect: Add generic interconnect driver for Exynos SoCs PM / devfreq: exynos-bus: Add registration of interconnect child device ARM: dts: exynos: Add interconnect properties to Exynos4412 bus nodes drm: exynos: mixer: Add interconnect support
.../devicetree/bindings/devfreq/exynos-bus.txt | 68 +++++++- arch/arm/boot/dts/exynos4412.dtsi | 7 + drivers/devfreq/exynos-bus.c | 17 ++ drivers/gpu/drm/exynos/exynos_mixer.c | 150 +++++++++++++++- drivers/interconnect/Kconfig | 1 + drivers/interconnect/Makefile | 1 + drivers/interconnect/exynos/Kconfig | 6 + drivers/interconnect/exynos/Makefile | 4 + drivers/interconnect/exynos/exynos.c | 192 +++++++++++++++++++++ 9 files changed, 436 insertions(+), 10 deletions(-) create mode 100644 drivers/interconnect/exynos/Kconfig create mode 100644 drivers/interconnect/exynos/Makefile create mode 100644 drivers/interconnect/exynos/exynos.c
-- 2.7.4