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From: Vivek Gautam <>
	Vivek Gautam <>
Subject: [PATCH v4 0/3] Qcom smmu-500 wait-for-safe handling for sdm845
Date: Fri, 23 Aug 2019 12:02:45 +0530	[thread overview]
Message-ID: <> (raw)

Previous version of the patches are at [1]:

Qcom's implementation of smmu-500 on sdm845 adds a hardware logic called
wait-for-safe. This logic helps in meeting the invalidation requirements
from 'real-time clients', such as display and camera. This wait-for-safe
logic ensures that the invalidations happen after getting an ack from these
In this patch-series we are disabling this wait-for-safe logic from the
arm-smmu driver's probe as with this enabled the hardware tries to
throttle invalidations from 'non-real-time clients', such as USB and UFS.

For detailed information please refer to patch [3/4] in this series.
I have included the device tree patch too in this series for someone who
would like to test out this. Here's a branch [2] that gets display on MTP
SDM845 device.

This patch series is inspired from downstream work to handle under-performance
issues on real-time clients on sdm845. In downstream we add separate page table
ops to handle TLB maintenance and toggle wait-for-safe in tlb_sync call so that
achieve required performance for display and camera [3, 4].

Changes since v3:
 * Based on arm-smmu implementation cleanup series [5] by Robin Murphy which is
   already merged in Will's tree [6].
 * Implemented the sdm845 specific reset hook which does arm_smmu_device_reset()
   followed by making SCM call to disable the wait-for-safe logic.
 * Removed depedency for SCM call on any dt flag. We invariably try to disable
   the wait-for-safe logic on sdm845. The platforms such as mtp845, and db845
   that implement handlers for this particular SCM call should be able disable
   wait-for-safe logic.
   Other platforms such as cheza don't enable the wait-for-safe logic at all
   from their bootloaders. So there's no need to disable the same.
 * No change in SCM call patches 1 & 2.

Changes since v2:
 * Dropped the patch to add atomic io_read/write scm API.
 * Removed support for any separate page table ops to handle wait-for-safe.
   Currently just disabling this wait-for-safe logic from arm_smmu_device_probe()
   to achieve performance on USB/UFS on sdm845.
 * Added a device tree patch to add smmu option for fw-implemented support
   for SCM call to take care of SAFE toggling.

Changes since v1:
 * Addressed Will and Robin's comments:
    - Dropped the patch[4] that forked out __arm_smmu_tlb_inv_range_nosync(),
      and __arm_smmu_tlb_sync().
    - Cleaned up the errata patch further to use downstream polling mechanism
      for tlb sync.
 * No change in SCM call patches - patches 1 to 3.


Vivek Gautam (3):
  firmware: qcom_scm-64: Add atomic version of qcom_scm_call
  firmware/qcom_scm: Add scm call to handle smmu errata
  iommu: arm-smmu-impl: Add sdm845 implementation hook

 drivers/firmware/qcom_scm-32.c |   5 ++
 drivers/firmware/qcom_scm-64.c | 149 +++++++++++++++++++++++++++++------------
 drivers/firmware/qcom_scm.c    |   6 ++
 drivers/firmware/qcom_scm.h    |   5 ++
 drivers/iommu/arm-smmu-impl.c  |  27 +++++++-
 include/linux/qcom_scm.h       |   2 +
 6 files changed, 149 insertions(+), 45 deletions(-)

QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member
of Code Aurora Forum, hosted by The Linux Foundation

             reply	other threads:[~2019-08-23  6:33 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-23  6:32 Vivek Gautam [this message]
2019-08-23  6:32 ` [PATCH v4 1/3] firmware: qcom_scm-64: Add atomic version of qcom_scm_call Vivek Gautam
2019-09-06 15:12   ` Stephen Boyd
2019-09-16  9:48     ` Sai Prakash Ranjan
2019-08-23  6:32 ` [PATCH v4 2/3] firmware/qcom_scm: Add scm call to handle smmu errata Vivek Gautam
2019-08-23  6:32 ` [PATCH v4 3/3] iommu: arm-smmu-impl: Add sdm845 implementation hook Vivek Gautam
2019-09-06  6:32   ` Vivek Gautam
2019-09-06 15:07   ` Stephen Boyd
2019-09-16  9:47     ` Sai Prakash Ranjan
2019-09-10 13:26   ` Robin Murphy
2019-09-16  9:46     ` Sai Prakash Ranjan

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