linux-kernel - [PATCH v2 0/3] clk: Implement a clock request API

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Date:   Tue, 14 Sep 2021 11:35:12 +0200
From:   Maxime Ripard <maxime@...no.tech>
To:     Mike Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>,
        dri-devel@...ts.freedesktop.org,
        Daniel Vetter <daniel.vetter@...el.com>,
        David Airlie <airlied@...ux.ie>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        Maxime Ripard <maxime@...no.tech>
Cc:     Maxime Ripard <mripard@...nel.org>, linux-clk@...r.kernel.org,
        Dave Stevenson <dave.stevenson@...pberrypi.com>,
        Phil Elwell <phil@...pberrypi.com>,
        Tim Gover <tim.gover@...pberrypi.com>,
        Dom Cobley <dom@...pberrypi.com>,
        Emma Anholt <emma@...olt.net>, linux-kernel@...r.kernel.org,
        Russell King <linux@...linux.org.uk>
Subject: [PATCH v2 0/3] clk: Implement a clock request API

Hi,

This is a follow-up of the discussion here:
https://lore.kernel.org/linux-clk/20210319150355.xzw7ikwdaga2dwhv@gilmour/

This implements a mechanism to raise and lower clock rates based on consumer
workloads, with an example of such an implementation for the RaspberryPi4 HDMI
controller.

There's a couple of things worth discussing:

  - The name is in conflict with clk_request_rate, and even though it feels
    like the right name to me, we should probably avoid any confusion

  - The code so far implements a policy of always going for the lowest rate
    possible. While we don't have an use-case for something else, this should
    maybe be made more flexible?

Let me know what you think
Maxime

Changes from v1:
  - Return NULL in clk_request_start if clk pointer is NULL
  - Test for clk_req pointer in clk_request_done
  - Add another user in vc4
  - Rebased on top of v5.15-rc1

Dom Cobley (1):
  drm/vc4: hvs: Convert to the new clock request API

Maxime Ripard (2):
  clk: Introduce a clock request API
  drm/vc4: hdmi: Convert to the new clock request API

 drivers/clk/clk.c              | 126 +++++++++++++++++++++++++++++++++
 drivers/gpu/drm/vc4/vc4_hdmi.c |  15 ++--
 drivers/gpu/drm/vc4/vc4_hdmi.h |   3 +
 drivers/gpu/drm/vc4/vc4_kms.c  |   5 +-
 include/linux/clk.h            |   4 ++
 5 files changed, 146 insertions(+), 7 deletions(-)

-- 
2.31.1