linux-kernel - Re: [PATCH v3 0/9] add support for Sama5d2 audio PLLs and enable ClassD

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Message-ID: <b3b59278-8c7f-b3d1-e143-7f013ac0b873@free-electrons.com>
Date:   Wed, 19 Jul 2017 08:28:17 +0200
From:   Quentin Schulz <quentin.schulz@...e-electrons.com>
To:     mturquette@...libre.com, sboyd@...eaurora.org, robh+dt@...nel.org,
        mark.rutland@....com, lgirdwood@...il.com, broonie@...nel.org,
        nicolas.ferre@...rochip.com, alexandre.belloni@...e-electrons.com,
        linux@...linux.org.uk, boris.brezillon@...e-electrons.com,
        perex@...ex.cz, tiwai@...e.com
Cc:     cyrille.pitchen@...ev4u.fr, thomas.petazzoni@...e-electrons.com,
        linux-clk@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, alsa-devel@...a-project.org,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v3 0/9] add support for Sama5d2 audio PLLs and enable
 ClassD

Hi all,

It's been almost a week with no comments on this patch set, so kindly
pinging.

Thanks,
Quentin

On 13/07/2017 09:49, Quentin Schulz wrote:
> This patch series adds support for the audio PLLs and enables ClassD that
> can be found in ATMEL Sama5d2 SoC.
> 
> There are two audio PLLs (PMC and PAD) that shares the same parent (FRAC).
> FRAC can output between 620 and 700MHz and only multiply the rate of its
> parent. The two audio PLLs then divide the FRAC rate to best match the
> asked rate.
> 
> I basically took an old patch series posted by Nicolas on December, 6th
> 2016[1][2][3] and the comments Boris did on the first version[4] Nicolas
> sent on July, 15th 2015.
> 
> I also fixed the function used to compute the divisors, removed useless
> spinlocks and added a range to the audio frac PLL to stay within vendor's
> supported range. Clocks that are children of gclk (generated-clk) are now
> able to propagate rate to the audio PLL clocks when needed.
> 
> However, there are multiple children clocks that could technically
> change the rate of audio_pll (via gck). With the rate locking introduced
> in Jerome Brunet's patch series[5], the first consumer to enable the clock
> will be the one definitely setting the rate of the clock. Without the rate
> locking, the last consumer to set the rate will be able to mess with the
> rate.
> Since audio IPs are most likely to request the same rate, we enforce
> that the only clks able to modify gck rate are those of audio IPs.
> 
> To remain consistent, we deny other clocks to be children of audio_pll.
> 
> Thanks,
> Quentin
> 
> [1] https://patchwork.kernel.org/patch/9462351/
> [2] https://patchwork.kernel.org/patch/9462347/
> [3] https://patchwork.kernel.org/patch/9462349/
> [4] https://www.spinics.net/lists/arm-kernel/msg436120.html
> [5] http://www.spinics.net/lists/linux-clk/msg17927.html
> 
> Cyrille Pitchen (2):
>   ARM: dts: at91: sama5d2: add classd nodes
>   ARM: dts: at91: sama5d2_xplained: add pin muxing and enable classd
> 
> Quentin Schulz (7):
>   clk: at91: clk-generated: remove useless divisor loop
>   clk: at91: add audio plls to the compatible list in DT binding
>   clk: at91: add audio pll clock drivers
>   clk: at91: clk-generated: create function to find best_diff
>   clk: at91: clk-generated: make gclk determine audio_pll rate
>   ASoC: atmel-classd: remove aclk clock from DT binding
>   ASoC: atmel-classd: remove aclk clock
> 
>  .../devicetree/bindings/clock/at91-clock.txt       |  10 +
>  .../devicetree/bindings/sound/atmel-classd.txt     |   9 +-
>  arch/arm/boot/dts/at91-sama5d2_xplained.dts        |  16 ++
>  arch/arm/boot/dts/sama5d2.dtsi                     |  39 +++-
>  arch/arm/mach-at91/Kconfig                         |   4 +
>  drivers/clk/at91/Makefile                          |   2 +
>  drivers/clk/at91/clk-audio-pll-pad.c               | 206 ++++++++++++++++++
>  drivers/clk/at91/clk-audio-pll-pmc.c               | 174 +++++++++++++++
>  drivers/clk/at91/clk-audio-pll.c                   | 239 +++++++++++++++++++++
>  drivers/clk/at91/clk-generated.c                   | 101 +++++++--
>  include/linux/clk/at91_pmc.h                       |  25 +++
>  sound/soc/atmel/atmel-classd.c                     |  47 ++--
>  12 files changed, 813 insertions(+), 59 deletions(-)
>  create mode 100644 drivers/clk/at91/clk-audio-pll-pad.c
>  create mode 100644 drivers/clk/at91/clk-audio-pll-pmc.c
>  create mode 100644 drivers/clk/at91/clk-audio-pll.c
> 

-- 
Quentin Schulz, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com