When there is no device to attach to the IOMMU domain, as may be the
case when the device-tree does not contain the proper iommu node, it is
best to keep going without IOMMU support rather than failing.
This allows the driver to probe and function instead of taking down
all of the tegra drm driver, leading to missing display support.

Signed-off-by: Paul Kocialkowski <contact@paulk.fr>
Fixes: 404bfb78daf3 ("gpu: host1x: Add IOMMU support")
Reviewed-by: Mikko Perttunen <mperttunen@nvidia.com>
Tested-by: Marcel Ziswiler <marcel.ziswiler@toradex.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20170710193305.5987-1-contact@paulk.fr

Backmerging airlied/drm-next

This is largely a rewrite of the Host1x channel allocation code, bringing
several changes:

- The previous code could deadlock due to an interaction
  between the 'reflock' mutex and CDMA timeout handling.
  This gets rid of the mutex.
- Support for more than 32 channels, required for Tegra186
- General refactoring, including better encapsulation
  of channel ownership handling into channel.c

Signed-off-by: Mikko Perttunen <mperttunen@nvidia.com>
Reviewed-by: Dmitry Osipenko <digetx@gmail.com>
Tested-by: Dmitry Osipenko <digetx@gmail.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>

If 'devm_reset_control_get' returns an error, then we erroneously return
success because error code is taken from 'host->clk' instead of
'host->rst'.

Fixes: b386c6b73ac6 ("gpu: host1x: Support module reset")
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Reviewed-by: Mikko Perttunen <mperttunen@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170410202922.17665-1-christophe.jaillet@wanadoo.fr

Newer versions of Tegra come with early boot software that aggressively
puts various modules in reset. Add support to the host1x driver to take
the module out of reset on probe, and assert reset on removal.

Signed-off-by: Thierry Reding <treding@nvidia.com>

Sorting includes alphabetically makes it easier and less conflict-prone
to add new includes subsequently.

Signed-off-by: Thierry Reding <treding@nvidia.com>

Add support for the Host1x unit to be located behind
an IOMMU. This is required when gather buffers may be
allocated non-contiguously in physical memory, as can
be the case when TegraDRM is also using the IOMMU.

Signed-off-by: Mikko Perttunen <mperttunen@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>

Insert a number of blank lines in places where they increase readability
of the code. Also collapse various variable declarations to shorten some
functions and finally rewrite some code for readability.

Signed-off-by: Thierry Reding <treding@nvidia.com>

Fix a couple of occurrences where no blank line was used to separate
variable declarations from code or where block comments were wrongly
formatted.

Signed-off-by: Thierry Reding <treding@nvidia.com>

The default DMA mask covers a 32 bits address range, but host1x devices
can address a larger range on TK1 and TX1. Set the DMA mask to the range
addressable when we use the IOMMU to prevent the use of bounce buffers.

Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>