405b4f6d21
commit a33b2431d11b4df137bbcfdd5a5adfa054c2479e upstream.
During USB transfers on the SC8280XP __arm_smmu_tlb_sync() is seen to
typically take 1-2ms to complete. As expected this results in poor
performance, something that has been mitigated by proposing running the
iommu in non-strict mode (boot with iommu.strict=0).
This turns out to be related to the SAFE logic, and programming the QOS
SAFE values in the DPU (per suggestion from Rob and Doug) reduces the
TLB sync time to below 10us, which means significant less time spent
with interrupts disabled and a significant boost in throughput.
Fixes: 4a352c2fc15a ("drm/msm/dpu: Introduce SC8280XP")
Cc: stable@vger.kernel.org
Suggested-by: Doug Anderson <dianders@chromium.org>
Suggested-by: Rob Clark <robdclark@chromium.org>
Signed-off-by: Bjorn Andersson <quic_bjorande@quicinc.com>
Tested-by: Johan Hovold <johan+linaro@kernel.org>
Tested-by: Steev Klimaszewski <steev@kali.org>
Reviewed-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
Patchwork: https://patchwork.freedesktop.org/patch/565094/
Link: https://lore.kernel.org/r/20231030-sc8280xp-dpu-safe-lut-v1-1-6d485d7b428f@quicinc.com
Signed-off-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.