From: Alex Riesen <alexander.riesen@cetitec.com>
To: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
Geert Uytterhoeven <geert@linux-m68k.org>,
Kieran Bingham <kieran.bingham@ideasonboard.com>,
Mauro Carvalho Chehab <mchehab@kernel.org>,
Hans Verkuil <hverkuil-cisco@xs4all.nl>,
Rob Herring <robh+dt@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Driver Development <devel@driverdev.osuosl.org>,
Linux Media <linux-media@vger.kernel.org>,
Linux Kernel <linux-kernel@vger.kernel.org>,
Device Tree <devicetree@vger.kernel.org>,
Renesas SoC <linux-renesas-soc@vger.kernel.org>
Subject: Re: [PATCH 8/8] arm64: dts: renesas: salvator: add a connection from adv748x codec (HDMI input) to the R-Car SoC
Date: Tue, 10 Mar 2020 09:17:14 +0100 [thread overview]
Message-ID: <20200310081714.GA11274@pflmari> (raw)
In-Reply-To: <87a74pvwz8.wl-kuninori.morimoto.gx@renesas.com>
Hello Morimoto-san,
Kuninori Morimoto, Tue, Mar 10, 2020 02:07:23 +0100:
> > Should the adv748x driver also implement anything to configure the frequency
> > of MCLK clock? I mean something like .set_sysclk and .set_fmt callbacks of
> > snd_soc_dai_ops?
> >
> > Or is the driver implementation, which depends on mclk-fs to be 256, the audio
> > stream format to be 8x S24_LE, and requires strictly 48kHz sampling rate on
> > the HDMI input, a totally acceptable first attempt at writing a DAI driver?
> >
> > I'm a bit bothered by that, as the hardware is also capable of decoding
> > stereo, sampling rate 32-192kHz, a variety of PCM and compressed/encrypted
> > formats, 128-768fs MCLK multipliers, and a row of I2S options.
> >
> > I just find it confusing to place the configuration interfaces.
> > For instance, the patches use the media ioctl for audio output selection to
> > select I2S protocol. While works, it does not feel right (shouldn't it be in
> > the device tree?)
> >
> > Maybe you can point me at a driver doing something similar? I'm studying media
> > drivers now, but not many of them use ASoC interfaces for devices providing a
> > clock. Or maybe I should better look at sound/soc/...?
>
> Setting Sound Clock for all cases/patterns are very complex and difficult actually.
> (ADV7482 configuration) x (ADG divider / selector) x etc, etc...
>
> Thus, Current R-Car sound is assuming that audio_clk_a/b/c/i are providing
> route clock (= no configuration, fixed clock), and ADG divides it,
> and provide best clock to each SSIx.
> Current Salvator/ULCB already have 44.1/48kHz route clock (= CS2000 and Audio_CLK_A),
> and we can reuse it for all SSIx. Thus, ADV7482 clock is not necessary, I guess ?
> Or providing specific clock for some case is enough
> (ADG will automatically select it if necessary).
In this particular case, the ADV7482 *must* provide the clock, I believe: it
extracts the audio stream from the HDMI connection (in addition to everything
else) and serves the stream on I2S. Its MCLK line is physically connected to
the CLK_C line (which is an input) of the R-Car SoC. The I2S audio
transmission does not work if the ADV7482 clock is not programmed (or
programmed incorrectly).
Yes, I tried (I also tried programming it incorrectly, just because I didn't
know what I was doing).
> If ADV7482 needs more detail clock settings combination,
> then, there is no method to adjust to it.
> We need to consider such system somehow.
Not encouraging...
Maybe I should leave the clock fixed, with the frequency configuration in the
device tree, e.g. as adv7482 port node property "clock-frequency".
Which feels rather pathetic, but at least serves my purpose (48k, 8x24).
But let me describe the situation as I see it first.
As far as I understand, the SSI4 (Salvator-X board) should be programmed by
the snd-soc-rcar driver in the "slave receiver" mode for this use case, which
is HDMI input ADV7482 (I2S master, TDM) -> SSI4 (I2S slave)):
[ 63.305990] asoc_simple_card_parse_clk: asoc-audio-graph-card sound: rsnd-dai.1 : sysclk = 66666664, direction 0
[ 63.306028] asoc_simple_card_parse_clk: asoc-audio-graph-card sound: adv748x-i2s : sysclk = 12288000, direction 1
I am a bit bothered by the fact that sysclk of rsnd-dai.1 does not match that
sysclk of adv7482-i2s, but I think it's just DT node configuration.
[ 63.306033] asoc_simple_card_set_dailink_name: asoc-audio-graph-card sound: name : rsnd-dai.1-adv748x-i2s
...
[ 63.332641] asoc-audio-graph-card sound: adv748x.4-0070 <-> rsnd-dai.1 mapping ok
...
[ 63.341317] dapm_connect_dai_link_widgets: rsnd-dai.1-adv748x-i2s: connected DAI link adv748x.4-0070:Capture -> ec500000.sound:DAI1 Capture
...
[ 128.961389] rsnd_write: rcar_sound ec500000.sound: w ssi[4] - SSICR ( 124) : 9ceb0100
Decoding this last line (9ceb0100) gives SSICR.TRMD (bit1) =0, SSICR.SCKD
(bit15) =0, SSICR.SWSD (bit14) =0. The combination is documented as "slave
receiver". Which, I assume, makes SSI4 use the external clock. Given the
received stream looks ok, something also must have set the dividers correctly.
From the above, I conclude, whatever the complexity of the audio system clock
configuration, it seems to be implemented for the case.
I only miss a more or less clear way to configure the I2S master (ADV7482, that is).
Regards,
Alex
next prev parent reply other threads:[~2020-03-10 8:17 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-13 14:19 [PATCH 0/8] media: i2c: adv748x: add support for HDMI audio Alex Riesen
2020-01-13 14:15 ` [PATCH 1/8] media: adv748x: add a device-specific wrapper for register block read Alex Riesen
2020-01-13 14:15 ` [PATCH 2/8] media: adv748x: add audio mute control and output selection ioctls Alex Riesen
2020-03-13 8:16 ` Hans Verkuil
2020-03-13 10:26 ` Alex Riesen
2020-03-13 10:52 ` Hans Verkuil
2020-03-13 11:00 ` Alex Riesen
2020-01-13 14:15 ` [PATCH 3/8] media: adv748x: add log_status ioctl Alex Riesen
2020-01-13 14:15 ` [PATCH 4/8] media: adv748x: reserve space for the audio (I2S) port in the driver structures Alex Riesen
2020-01-13 14:15 ` [PATCH 5/8] media: adv748x: add an ASoC DAI definition to the driver Alex Riesen
2020-01-13 14:15 ` [PATCH 6/8] media: adv748x: reduce amount of code for bitwise modification of device registers Alex Riesen
2020-01-13 14:15 ` [PATCH 7/8] dt-bindings: adv748x: add information about serial audio interface (I2S/TDM) Alex Riesen
2020-01-13 22:32 ` Rob Herring
2020-01-13 14:15 ` [PATCH 8/8] arm64: dts: renesas: salvator: add a connection from adv748x codec (HDMI input) to the R-Car SoC Alex Riesen
2020-03-02 12:28 ` Geert Uytterhoeven
2020-03-02 13:40 ` Alex Riesen
2020-03-02 13:47 ` Geert Uytterhoeven
2020-03-02 15:07 ` Alex Riesen
2020-03-02 15:32 ` Geert Uytterhoeven
2020-03-02 16:09 ` Alex Riesen
2020-03-02 16:13 ` Geert Uytterhoeven
2020-03-05 14:36 ` Alex Riesen
2020-03-06 12:21 ` Geert Uytterhoeven
2020-03-06 13:16 ` Laurent Pinchart
2020-03-06 13:41 ` Alex Riesen
2020-03-06 13:45 ` Laurent Pinchart
2020-03-09 1:31 ` Kuninori Morimoto
2020-03-09 11:09 ` Alex Riesen
2020-03-10 1:07 ` Kuninori Morimoto
2020-03-10 8:17 ` Alex Riesen [this message]
2020-03-10 10:39 ` Laurent Pinchart
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