[PATCH v4 00/37] Introduce memory interconnect for NVIDIA Tegra SoCs

Dmitry Osipenko
2020-06-09T13:14:43Z

Hello,

This series brings initial support for memory interconnect to Tegra20 and
Tegra30 SoCs.

For the starter only display controllers are getting interconnect API
support, others could be supported later on. The display controllers
have the biggest demand for interconnect API right now because dynamic
memory frequency scaling can't be done safely without taking into account
bandwidth requirement from the displays.

Changelog:

v4: - All drivers that use interconnect API now select it in the Kconfig in
order to properly express the build dependency.

- The IS_ENABLED(CONFIG_INTERCONNECT) is dropped now from all patches.

- Added MODULE_AUTHOR() to the modularized drivers, for completeness.

- Added missed TEGRA_MC Kconfig dependency for the Tegra20 EMC driver.

- Added more acks from Rob Herring that I accidentally missed to add in v3.

v3: - Added acks from Rob Herring that were given to some of the v2 patches.

- Specified name of the TRM documentation chapter in the patch
"dt-bindings: host1x: Document new interconnect properties", which was
suggested by Rob Herring in the review comment to v2.

- Added patches that allow EMC drivers to be compiled as a loadable kernel
modules. This came up during of the v2 review when Georgi Djakov pointed
out that interconnect-core could be compiled as a kernel module. Please
note that the Tegra124 EMC driver is compile-tested only, I don't have
Tegra124 HW.

- In the review comment to [1] Stephen Boyd suggested that it will be
better not to make changes to clk API, which was needed in order to
avoid clashing of the interconnect driver with the devfreq in regards
to memory clk-rate rounding.

[1] https://patchwork.ozlabs.org/project/linux-tegra/patch/20200330231617.17079-3-digetx@gmail.com/

Stephen Boyd suggested that instead we should provide OPP table via DT.
I tried to investigate whether this could be done and turned out
it's a bit complicated. Technically it should be doable, but:

1. For now we don't fully support voltage scaling of the CORE regulator
and so OPP table in the DT isn't really needed today. We can
generate table from the memory timings, which is what Tegra devfreq
drivers already do.

2. The OPP table should be defined in the DT for the Memory Controller
node and then its usage somehow should be shared by both interconnect
and devfreq drivers. It's not obvious what's the best way to do it.

So, it will be much better to postpone the DT OPP table addition
until these questions are resolved. We can infer OPPs from the
memory timings and we could get the memory rates from the memory
driver directly, avoiding the problems induced by the clk API usage.
This idea is implemented in v3, see these patches:

PM / devfreq: tegra20: Use MC timings for building OPP table
PM / devfreq: tegra30: Use MC timings for building OPP table

v2: - Instead of a single dma-mem interconnect path, the paths are now
defined per memory client.

- The EMC provider now uses #interconnect-cells=<0>.

- Dropped Tegra124 because there is no enough information about how to
properly calculate required EMC clock rate for it and I don't have
hardware for testing. Somebody else will have to work on it.

- Moved interconnect providers code into drivers/memory/tegra/*.

- Added "Create tegra20-devfreq device" patch because interconnect
is not very usable without the devfreq memory auto-scaling since
memory freq will be fixed to the display's requirement.

Artur Świgoń (1):
interconnect: Relax requirement in of_icc_get_from_provider()

Dmitry Osipenko (36):
clk: Export clk_hw_reparent()
clk: tegra: Remove Memory Controller lock
clk: tegra: Export Tegra20 EMC kernel symbols
memory: tegra20-emc: Make driver modular
memory: tegra30-emc: Make driver modular
memory: tegra124-emc: Make driver modular
memory: tegra124-emc: Use devm_platform_ioremap_resource
soc/tegra: fuse: Export tegra_read_ram_code()
memory: tegra20-emc: Initialize MC timings
PM / devfreq: tegra20: Silence deferred probe error
PM / devfreq: tegra30: Silence deferred probe error
PM / devfreq: tegra20: Use MC timings for building OPP table
PM / devfreq: tegra30: Use MC timings for building OPP table
PM / devfreq: tegra20: Add error messages to tegra_devfreq_target()
PM / devfreq: tegra30: Add error messages to tegra_devfreq_target()
PM / devfreq: tegra20: Adjust clocks conversion ratio and polling
interval
PM / devfreq: tegra20: Relax Kconfig dependency
dt-bindings: memory: tegra20: mc: Document new interconnect property
dt-bindings: memory: tegra20: emc: Document new interconnect property
dt-bindings: memory: tegra30: mc: Document new interconnect property
dt-bindings: memory: tegra30: emc: Document new interconnect property
dt-bindings: host1x: Document new interconnect properties
dt-bindings: memory: tegra20: Add memory client IDs
dt-bindings: memory: tegra30: Add memory client IDs
ARM: tegra: Add interconnect properties to Tegra20 device-tree
ARM: tegra: Add interconnect properties to Tegra30 device-tree
memory: tegra: Register as interconnect provider
memory: tegra20-emc: Use devm_platform_ioremap_resource
memory: tegra20-emc: Continue probing if timings are missing in
device-tree
memory: tegra20-emc: Register as interconnect provider
memory: tegra20-emc: Create tegra20-devfreq device
memory: tegra30-emc: Continue probing if timings are missing in
device-tree
memory: tegra30-emc: Register as interconnect provider
drm/tegra: dc: Support memory bandwidth management
drm/tegra: dc: Tune up high priority request controls for Tegra20
drm/tegra: dc: Extend debug stats with total number of events

.../display/tegra/nvidia,tegra20-host1x.txt | 68 +++++
.../memory-controllers/nvidia,tegra20-emc.txt | 2 +
.../memory-controllers/nvidia,tegra20-mc.txt | 3 +
.../nvidia,tegra30-emc.yaml | 6 +
.../memory-controllers/nvidia,tegra30-mc.yaml | 5 +
arch/arm/boot/dts/tegra20.dtsi | 22 +-
arch/arm/boot/dts/tegra30.dtsi | 23 +-
drivers/clk/clk.c | 1 +
drivers/clk/tegra/clk-divider.c | 4 +-
drivers/clk/tegra/clk-tegra114.c | 6 +-
drivers/clk/tegra/clk-tegra124-emc.c | 63 ++--
drivers/clk/tegra/clk-tegra124.c | 8 +-
drivers/clk/tegra/clk-tegra20-emc.c | 3 +
drivers/clk/tegra/clk-tegra20.c | 3 +-
drivers/clk/tegra/clk-tegra30.c | 3 +-
drivers/clk/tegra/clk.h | 14 +-
drivers/devfreq/Kconfig | 2 +-
drivers/devfreq/tegra20-devfreq.c | 52 ++--
drivers/devfreq/tegra30-devfreq.c | 115 +++++--
drivers/gpu/drm/tegra/Kconfig | 1 +
drivers/gpu/drm/tegra/dc.c | 289 +++++++++++++++++-
drivers/gpu/drm/tegra/dc.h | 13 +
drivers/gpu/drm/tegra/drm.c | 19 ++
drivers/gpu/drm/tegra/plane.c | 1 +
drivers/gpu/drm/tegra/plane.h | 4 +-
drivers/interconnect/core.c | 11 +-
drivers/memory/tegra/Kconfig | 9 +-
drivers/memory/tegra/mc.c | 117 +++++++
drivers/memory/tegra/mc.h | 8 +
drivers/memory/tegra/tegra124-emc.c | 36 ++-
drivers/memory/tegra/tegra20-emc.c | 215 +++++++++++--
drivers/memory/tegra/tegra30-emc.c | 156 ++++++++--
drivers/soc/tegra/fuse/tegra-apbmisc.c | 2 +
include/dt-bindings/memory/tegra20-mc.h | 53 ++++
include/dt-bindings/memory/tegra30-mc.h | 67 ++++
include/linux/clk/tegra.h | 11 +
include/soc/tegra/emc.h | 16 -
include/soc/tegra/mc.h | 3 +
38 files changed, 1235 insertions(+), 199 deletions(-)
delete mode 100644 include/soc/tegra/emc.h

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2.26.0