Received-SPF: pass (google.com: domain of linux-kernel+bounces-100306-linux.lists.archive=gmail.com@vger.kernel.org designates 2604:1380:4601:e00::3 as permitted sender) client-ip=2604:1380:4601:e00::3;
Date: Tue, 12 Mar 2024 13:51:02 +0000
From: Charles Keepax <ckeepax@opensource.cirrus.com>
To: Andrejs Cainikovs <andrejs.cainikovs@toradex.com>
CC: Andrejs Cainikovs <andrejs.cainikovs@gmail.com>,
        <patches@opensource.cirrus.com>, <linux-sound@vger.kernel.org>,
        <linux-kernel@vger.kernel.org>, Liam Girdwood <lgirdwood@gmail.com>,
        "Mark
 Brown" <broonie@kernel.org>, Jaroslav Kysela <perex@perex.cz>,
        Takashi Iwai
	<tiwai@suse.com>
Subject: Re: [RFC PATCH v1] ASoC: wm8904: enable fll with fixed mclk
Message-ID: <ZfBdxrzX3EnPuGOn@ediswmail9.ad.cirrus.com>
References: <20240308155831.141229-1-andrejs.cainikovs@gmail.com>
 <Ze7smWSeoCVIcxIo@ediswmail9.ad.cirrus.com>
 <ZfBG9IMFEjjIdgdi@toradex.com>
Precedence: bulk
MIME-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-Disposition: inline
In-Reply-To: <ZfBG9IMFEjjIdgdi@toradex.com>

On Tue, Mar 12, 2024 at 01:13:40PM +0100, Andrejs Cainikovs wrote:
> On Mon, Mar 11, 2024 at 11:35:53AM +0000, Charles Keepax wrote:
> > On Fri, Mar 08, 2024 at 04:58:31PM +0100, Andrejs Cainikovs wrote:
> > > From: Andrejs Cainikovs <andrejs.cainikovs@toradex.com>
> With or without mclk-fs wm8904_set_sysclk() is called always during probe,
> with following parameters:
> 
> clk_id = 0
> dir = 0
> freq = 25000000
> mclk_freq = 25000000
> 
> When mclk-fs is set, wm8904_set_sysclk() is also called before each
> playback [1]. In case of 44.1kHz:
> 
> clk_id = 0
> dir = 0
> freq = 11289600
> mclk_freq = 11235955
> 
> In both scenarios, clk_id is always WM8904_CLK_AUTO.

Ah, ok I see what I was missing here. simple_card_utils calls
clk_set_rate if you specify mclk_fs. Which you don't want in this
case. My gut reaction is that really the problem here is the machine
driver doesn't support the clocking setup you have.

Having a quick look through the simple card stuff can you remove:

	clocks = <&audio_refclk1>;

From the machine driver DT stuff, and add mclk-fs. I think that
should cause the simple card to call the codec dai_set_sysclk
but without ever touching the audio_refclk. A small change in
simple_util_parse_clk might also be needed to allow it to return
without finding a clock. Which feels like a much simpler and less
scary change.

My only slight reservation is the automatic clocking thing only
really exists as a hack to support simple card anyway. But overal
I think it might be better to try to move the direction of travel
more to adding support for the clocking systems that exist into
simple-card rather than tweaking the codec driver to work around
it.

Thanks,
Charles