linux-kernel - Re: [PATCH 0/2] clk: Implement a clock request API

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Message-ID: <161981637939.1363782.4943687720432536625@swboyd.mtv.corp.google.com>
Date:   Fri, 30 Apr 2021 13:59:39 -0700
From:   Stephen Boyd <sboyd@...nel.org>
To:     Daniel Vetter <daniel.vetter@...el.com>,
        David Airlie <airlied@...ux.ie>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Maxime Ripard <maxime@...no.tech>,
        Mike Turquette <mturquette@...libre.com>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        dri-devel@...ts.freedesktop.org
Cc:     Eric Anholt <eric@...olt.net>, Daniel Vetter <daniel@...ll.ch>,
        linux-kernel@...r.kernel.org, Russell King <linux@...linux.org.uk>,
        Dave Stevenson <dave.stevenson@...pberrypi.com>,
        Phil Elwell <phil@...pberrypi.com>,
        Tim Gover <tim.gover@...pberrypi.com>,
        Dom Cobley <dom@...pberrypi.com>, linux-clk@...r.kernel.org,
        Maxime Ripard <mripard@...nel.org>
Subject: Re: [PATCH 0/2] clk: Implement a clock request API

Quoting Maxime Ripard (2021-04-13 03:13:18)
> 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?

I'm definitely confused how it is different from the
clk_set_rate_exclusive() API and associated
clk_rate_exclusive_get()/clk_rate_exclusive_put(). Can you explain
further the differences in the cover letter here?

> 
> Let me know what you think
> Maxime
>