On Thu, Aug 25, 2016 at 7:07 PM, Horng-Shyang Liao [off-list ref] wrote:

Hi Matthias,

On Wed, 2016-08-24 at 13:00 +0200, Matthias Brugger wrote:

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On 24/08/16 05:27, HS Liao wrote:

[...]

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Changes since v12:
 - remove mediatek,gce from device tree

Why? The binding got accepted by Rob.

We can get cmdq dev from mailbox controller,
so we don't need mediatek,gce anymore.

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Best regards,
HS Liao

HS Liao (4):
  dt-bindings: soc: Add documentation for the MediaTek GCE unit
  CMDQ: Mediatek CMDQ driver
  arm64: dts: mt8173: Add GCE node
  CMDQ: save more energy in idle

 .../devicetree/bindings/soc/mediatek/gce.txt       |  44 +
 arch/arm64/boot/dts/mediatek/mt8173.dtsi           |  10 +
 drivers/soc/mediatek/Kconfig                       |  11 +
 drivers/soc/mediatek/Makefile                      |   1 +
 drivers/soc/mediatek/mtk-cmdq.c                    | 983 +++++++++++++++++++++

The driver uses the mailbox framework, so it should live in the
drivers/mailbox folder.

As you know, the maximum number of gce threads is 16.
However, we plan to support more clients in the future,
and they may need to use more than 16 gce threads.

For this issue, our plan is to let multiple clients share the same gce
thread; i.e. we will acquire gce thread for client dynamically by
internal policy in cmdq driver.
Unfortunately. mailbox channel has exclusive feature.
Quote from comment of mbox_request_channel().
"The channel is exclusively allocated and can't be used by another
client before the owner calls mbox_free_channel."
Therefore, we plan to remove mailbox framework from cmdq driver in the
future.

Platforms that need shared access to a channel, implement a 'server'
driver that serialise (which is needed still) the access to common
channel. If you think you don't need mutual exclusion and don't care
about replies, simply share the mailbox handle among different
clients.