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  1. 09 Aug, 2019 3 commits
    • Suman Anna's avatar
      iommu/omap: streamline enable/disable through runtime pm callbacks · db8918f6
      Suman Anna authored 
      The OMAP IOMMU devices are typically present within the respective
client processor subsystem and have their own dedicated hard-reset
line. Enabling an IOMMU requires the reset line to be deasserted
and the clocks to be enabled before programming the necessary IOMMU
registers. The IOMMU disable sequence follow the reverse order of
enabling. The OMAP IOMMU driver programs the reset lines through
pdata ops to invoke the omap_device_assert/deassert_hardreset API.
The clocks are managed through the pm_runtime framework, and the
callbacks associated with the device's pm_domain, implemented in
the omap_device layer.

Streamline the enable and disable sequences in the OMAP IOMMU
driver by implementing all the above operations within the
runtime pm callbacks. All the OMAP devices have device pm_domain
callbacks plugged in the omap_device layer for automatic runtime
management of the clocks. Invoking the reset management functions
within the runtime pm callbacks in OMAP IOMMU driver therefore
requires that the default device's pm domain callbacks in the
omap_device layer be reset, as the ordering sequence for managing
the reset lines and clocks from the pm_domain callbacks don't gel
well with the implementation in the IOMMU driver callbacks. The
omap_device_enable/omap_device_idle functions are invoked through
the newly added pdata ops.

Consolidating all the device management sequences within the
runtime pm callbacks allows the driver to easily support both
system suspend/resume and runtime suspend/resume using common
code.
Signed-off-by: default avatarSuman Anna <s-anna@ti.com>
Signed-off-by: default avatarJoerg Roedel <jroedel@suse.de>
      db8918f6
    • Suman Anna's avatar
      iommu/omap: add pdata ops for omap_device_enable/idle · 74c116df
      Suman Anna authored 
      Add two new platform data ops to allow the OMAP iommu driver to
be able to invoke the omap_device_enable and omap_device_idle
from within the driver. These are being added to streamline the
sequence between managing the hard reset lines and the clocks
during the suspend path, as the default device pm_domain callback
sequences in omap_device layer are not conducive for the OMAP
IOMMU driver.

This could have been done by expanding the existing pdata ops
for reset management (like in the OMAP remoteproc driver), but
this was chosen to avoid adding additional code in the separate
file in the mach-omap2 layer.
Signed-off-by: default avatarSuman Anna <s-anna@ti.com>
Signed-off-by: default avatarJoerg Roedel <jroedel@suse.de>
      74c116df
    • Suman Anna's avatar
      iommu/omap: fix boot issue on remoteprocs with AMMU/Unicache · 3846a3b9
      Suman Anna authored 
      Support has been added to the OMAP IOMMU driver to fix a boot hang
issue on OMAP remoteprocs with AMMU/Unicache, caused by an improper
AMMU/Unicache state upon initial deassertion of the processor reset.
The issue is described in detail in the next three paragraphs.

All the Cortex M3/M4 IPU processor subsystems in OMAP SoCs have a
AMMU/Unicache IP that dictates the memory attributes for addresses
seen by the processor cores. The AMMU/Unicache is configured/enabled
by the SCACHE_CONFIG.BYPASS bit - a value of 1 enables the cache and
mandates all addresses accessed by M3/M4 be defined in the AMMU. This
bit is not programmable from the host processor. The M3/M4 boot
sequence starts out with the AMMU/Unicache in disabled state, and
SYS/BIOS programs the AMMU regions and enables the Unicache during
one of its initial boot steps. This SCACHE_CONFIG.BYPASS bit is
however enabled by default whenever a RET reset is applied to the IP,
irrespective of whether it was previously enabled or not. The AMMU
registers lose their context whenever this reset is applied. The reset
is effective as long as the MMU portion of the subsystem is enabled
and clocked. This behavior is common to all the IPU and DSP subsystems
that have an AMMU/Unicache.

The IPU boot sequence involves enabling and programming the MMU, and
loading the processor and releasing the reset(s) for the processor.
The PM setup code currently sets the target state for most of the
power domains to RET. The L2 MMU can be enabled, programmed and
accessed properly just fine with the domain in hardware supervised
mode, while the power domain goes through a RET->ON->RET transition
during the programming sequence. However, the ON->RET transition
asserts a RET reset, and the SCACHE_CONFIG.BYPASS bit gets auto-set.
An AMMU fault is thrown immediately when the M3/M4 core's reset is
released since the first instruction address itself will not be
defined in any valid AMMU regions. The ON->RET transition happens
automatically on the power domain after enabling the iommu due to
the hardware supervised mode.

This patch adds and invokes the .set_pwrdm_constraint pdata ops, if
present, during the OMAP IOMMU enable and disable functions to resolve
the above boot hang issue. The ops will allow to invoke a mach-omap2
layer API pwrdm_set_next_pwrst() in a multi-arch kernel environment.
The ops also returns the current power domain state while enforcing
the constraint so that the driver can store it and use it to set back
the power domain state while releasing the constraint. The pdata ops
implementation restricts the target power domain to ON during enable,
and back to the original power domain state during disable, and thereby
eliminating the conditions for the boot issue. The implementation is
effective only when the original power domain state is either RET or
OFF, and is a no-op when it is ON or INACTIVE.

The .set_pwrdm_constraint ops need to be plugged in pdata-quirks
for the affected remote processors to be able to boot properly.

Note that the current issue is seen only on kernels with the affected
power domains programmed to enter RET. For eg., IPU1 on DRA7xx is in a
separate domain and is susceptible to this bug, while the IPU2 subsystem
is within CORE power domain, and CORE RET is not supported on this SoC.
IPUs on OMAP4 and OMAP5 are also susceptible since they are in CORE power
domain, and CORE RET is a valid power target on these SoCs.
Signed-off-by: default avatarSuman Anna <s-anna@ti.com>
Signed-off-by: default avatarJoerg Roedel <jroedel@suse.de>
      3846a3b9
  3. 05 Aug, 2019 1 commit
  5. 04 Aug, 2019 10 commits
  7. 03 Aug, 2019 26 commits
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