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git://git.kernel.org/pub/scm/linux/kernel/git/tegra/linux into next/drivers
Merge "ARM: tegra: Add EMC driver for v4.2-rc1" from Thierry Reding:
This introduces the EMC driver that's required to scale the external
memory frequency.
* tag 'tegra-for-4.2-emc' of git://git.kernel.org/pub/scm/linux/kernel/git/tegra/linux:
memory: tegra: Add EMC frequency debugfs entry
memory: tegra: Add EMC (external memory controller) driver
memory: tegra: Add API needed by the EMC driver
of: Add Tegra124 EMC bindings
of: Document timings subnode of nvidia,tegra-mc
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This file in debugfs can be used to get or set the EMC frequency.
Reading the file will return the currently set frequency in Hz, while
writing the file sets the specified frequency rounded to the next
highest frequency supported by the board.
Will be very useful when tuning memory scaling.
Signed-off-by: Mikko Perttunen <mperttunen@nvidia.com>
Signed-off-by: Tomeu Vizoso <tomeu.vizoso@collabora.com>
[treding@nvidia.com: add "emc" debugfs directory]
Signed-off-by: Thierry Reding <treding@nvidia.com>
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Implements functionality needed to change the rate of the memory bus
clock.
Signed-off-by: Mikko Perttunen <mperttunen@nvidia.com>
Signed-off-by: Tomeu Vizoso <tomeu.vizoso@collabora.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
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The EMC driver needs to know the number of external memory devices and
also needs to update the EMEM configuration based on the new rate of the
memory bus.
To know how to update the EMEM config, looks up the values of the burst
regs in the DT, for a given timing.
Signed-off-by: Mikko Perttunen <mperttunen@nvidia.com>
Signed-off-by: Tomeu Vizoso <tomeu.vizoso@collabora.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
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As this interrupt is just for development purposes, as the TRM says, and
the sheer amount of interrupts fired can seriously disrupt userspace
when testing the lower frequencies supported by the EMC.
From the TRM:
"There is one performance warning type interrupt: ARBITRATION_EMEM. It
fires when the MC detects that a request has been pending in the Row
Sorter long enough to hit the DEADLOCK_PREVENTION_SLACK_THRESHOLD. In
addition to true performance problems, this interrupt may fire in
situations such as clock-change where the EMC backpressures pending
traffic for long periods of time. This interrupt helps developers
identify and debug performance issues and configuration issues."
Signed-off-by: Tomeu Vizoso <tomeu.vizoso@collabora.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
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The memory controller on Tegra132 is very similar to the one found on
Tegra124. But the Denver CPUs don't have an outer cache, so dcache
maintenance is done slightly differently.
Signed-off-by: Thierry Reding <treding@nvidia.com>
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Subsequent patches will add debugfs files that print the status of the
SWGROUPs. Add a new names field and complement the SoC tables with the
names of the individual SWGROUPs.
Signed-off-by: Thierry Reding <treding@nvidia.com>
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The memory controller on NVIDIA Tegra exposes various knobs that can be
used to tune the behaviour of the clients attached to it.
Currently this driver sets up the latency allowance registers to the HW
defaults. Eventually an API should be exported by this driver (via a
custom API or a generic subsystem) to allow clients to register latency
requirements.
This driver also registers an IOMMU (SMMU) that's implemented by the
memory controller. It is supported on Tegra30, Tegra114 and Tegra124
currently. Tegra20 has a GART instead.
The Tegra SMMU operates on memory clients and SWGROUPs. A memory client
is a unidirectional, special-purpose DMA master. A SWGROUP represents a
set of memory clients that form a logical functional unit corresponding
to a single device. Typically a device has two clients: one client for
read transactions and one client for write transactions, but there are
also devices that have only read clients, but many of them (such as the
display controllers).
Because there is no 1:1 relationship between memory clients and devices
the driver keeps a table of memory clients and the SWGROUPs that they
belong to per SoC. Note that this is an exception and due to the fact
that the SMMU is tightly integrated with the rest of the Tegra SoC. The
use of these tables is discouraged in drivers for generic IOMMU devices
such as the ARM SMMU because the same IOMMU could be used in any number
of SoCs and keeping such tables for each SoC would not scale.
Acked-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Thierry Reding <treding@nvidia.com>
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