Add reset hook for sdm845 based platforms to turn off
the wait-for-safe sequence.
Understanding how wait-for-safe logic affects USB and UFS performance
on MTP845 and DB845 boards:
Qcom's implementation of arm,mmu-500 adds a WAIT-FOR-SAFE logic
to address under-performance issues in real-time clients, such as
Display, and Camera.
On receiving an invalidation requests, the SMMU forwards SAFE request
to these clients and waits for SAFE ack signal from real-time clients.
The SAFE signal from such clients is used to qualify the start of
invalidation.
This logic is controlled by chicken bits, one for each - MDP (display),
IFE0, and IFE1 (camera), that can be accessed only from secure software
on sdm845.
This configuration, however, degrades the performance of non-real time
clients, such as USB, and UFS etc. This happens because, with wait-for-safe
logic enabled the hardware tries to throttle non-real time clients while
waiting for SAFE ack signals from real-time clients.
On mtp845 and db845 devices, with wait-for-safe logic enabled by the
bootloaders we see degraded performance of USB and UFS when kernel
enables the smmu stage-1 translations for these clients.
Turn off this wait-for-safe logic from the kernel gets us back the perf
of USB and UFS devices until we re-visit this when we start seeing perf
issues on display/camera on upstream supported SDM845 platforms.
The bootloaders on these boards implement secure monitor callbacks to
handle a specific command - QCOM_SCM_SVC_SMMU_PROGRAM with which the
logic can be toggled.
There are other boards such as cheza whose bootloaders don't enable this
logic. Such boards don't implement callbacks to handle the specific SCM
call so disabling this logic for such boards will be a no-op.
This change is inspired by the downstream change from Patrick Daly
to address performance issues with display and camera by handling
this wait-for-safe within separte io-pagetable ops to do TLB
maintenance. So a big thanks to him for the change and for all the
offline discussions.
Without this change the UFS reads are pretty slow:
$ time dd if=/dev/sda of=/dev/zero bs=1048576 count=10 conv=sync
10+0 records in
10+0 records out
10485760 bytes (10.0MB) copied, 22.394903 seconds, 457.2KB/s
real 0m 22.39s
user 0m 0.00s
sys 0m 0.01s
With this change they are back to rock!
$ time dd if=/dev/sda of=/dev/zero bs=1048576 count=300 conv=sync
300+0 records in
300+0 records out
314572800 bytes (300.0MB) copied, 1.030541 seconds, 291.1MB/s
real 0m 1.03s
user 0m 0.00s
sys 0m 0.54s
Signed-off-by: Vivek Gautam <vivek.gautam@codeaurora.org>
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org>
Signed-off-by: Will Deacon <will@kernel.org>
Many of the device-specific implementation details in 'arm-smmu-impl.c'
are exposed to other compilation units. Whilst we may require this in
the future, let's make it all 'static' for now so that we can expose
things on a case-by-case basic.
Signed-off-by: Will Deacon <will@kernel.org>
Allocating and initialising a context for a domain is another point
where certain implementations are known to want special behaviour.
Currently the other half of the Cavium workaround comes into play here,
so let's finish the job to get the whole thing right out of the way.
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>
Reset is an activity rife with implementation-defined poking. Add a
corresponding hook, and use it to encapsulate the existing MMU-500
details.
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>
Probing the ID registers and setting up the SMMU configuration is an
area where overrides and workarounds may well be needed. Indeed, the
Cavium workaround detection lives there at the moment, so let's break
that out.
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>
Move detection of the Secure access quirk to its new home, trimming it
down in the process - time has proven that boolean DT flags are neither
ideal nor necessarily sufficient, so it's highly unlikely we'll ever add
more, let alone enough to justify the frankly overengineered parsing
machinery.
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>
Add some nascent infrastructure for handling implementation-specific
details outside the flow of the architectural code. This will allow us
to keep mutually-incompatible vendor-specific hooks in their own files
where the respective interested parties can maintain them with minimal
chance of conflicts. As somewhat of a template, we'll start with a
general place to collect the relatively trivial existing quirks.
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>
