From: Michael Walle <michael@walle.cc>
To: Sameer Pujar <spujar@nvidia.com>
Cc: devicetree@vger.kernel.org, alsa-devel@alsa-project.org,
kuninori.morimoto.gx@renesas.com, robh@kernel.org,
linux-kernel@vger.kernel.org, jonathanh@nvidia.com,
sharadg@nvidia.com, Mark Brown <broonie@kernel.org>,
thierry.reding@gmail.com, linux-tegra@vger.kernel.org
Subject: Re: [PATCH 1/3] ASoC: simple-card-utils: Fix device module clock
Date: Mon, 15 Mar 2021 16:33:57 +0100 [thread overview]
Message-ID: <33a5c89d15ca04ad75f9993bd5d22cb9@walle.cc> (raw)
In-Reply-To: <6af6439c-bdb8-cd0f-635d-069040ba5b65@nvidia.com>
Am 2021-03-15 16:19, schrieb Sameer Pujar:
> On 3/15/2021 5:35 PM, Michael Walle wrote:
>> External email: Use caution opening links or attachments
>>
>>
>> Am 2021-03-12 14:46, schrieb Mark Brown:
>>> On Fri, Mar 12, 2021 at 01:30:02PM +0100, Michael Walle wrote:
>>>
>>>> The card calls set_sysclk(), which eventually ends up in the codec.
>>>> The codec therefore, could figure out if it needs to configure the
>>>> clock or if it can use its internal FLL.
>>>> Is that what you mean?
>>>
>>> Yes.
>>>
>>>> But the set_sysclk() of the codec isn't even called, because the
>>>> card itself already tries to call clk_set_rate() on the Codec's
>>>> MCLK,
>>>> which returns with an error [0].
>>>
>>> OK, so I think we need to push this down a level so that the clock
>>> setting is implemented by the core/CODEC rather than by simple-card,
>>> with the helpers being something the CODEC can opt out of.
>>
>> Sameer, it looks like the proper fix should be to add the clock
>> support to your codec.
>
> I agree that complicated clock relationships should be handled within
> the codec itself, however MCLK rate setting depends on "mclk-fs"
> factor and this property is specified as part of
> simple-card/audio-graph-card codec subnode. Right now codec, in
> general, does not have a way to know this. The set_sysclk() callback
> takes rate argument and not the factor.
Why would you need the factor?
> Moreover the same codec is
> used by other platform vendors too and unless a new DT property is
> added for codec, runtime MCLK update based on the scaling factor
> cannot be supported.
Could you test the following:
diff --git a/sound/soc/codecs/rt5659.c b/sound/soc/codecs/rt5659.c
index 67f0ab817135..7fd41f51f856 100644
--- a/sound/soc/codecs/rt5659.c
+++ b/sound/soc/codecs/rt5659.c
@@ -3426,12 +3426,18 @@ static int rt5659_set_component_sysclk(struct
snd_soc_component *component, int
{
struct rt5659_priv *rt5659 =
snd_soc_component_get_drvdata(component);
unsigned int reg_val = 0;
+ int ret;
if (freq == rt5659->sysclk && clk_id == rt5659->sysclk_src)
return 0;
switch (clk_id) {
case RT5659_SCLK_S_MCLK:
+ ret = clk_set_rate(rt5659->mclk, freq);
+ if (ret)
+ return ret;
reg_val |= RT5659_SCLK_SRC_MCLK;
break;
case RT5659_SCLK_S_PLL1:
-michael
> This would mean that we will be having two
> methods to specify "mclk-fs" factor, one from
> simple-card/audio-graph-card and one from respective codec nodes,
> which does not seem ideal.
>
> Also it does not seem consistent with the way we handle MCLK clock
> based on where it is specified.
>
> a) If specified in simple-card/audio-graph-card, MCLK clock
> rate/enable/disable updates are allowed.
>
> b) If specified in codec device node, it is not expected to touch
> the MCLK clock. This patch tried to treat it the same way as (a) does.
> Advantage of this is, all codec drivers need not explicitly handle
> MCLK, instead it is done at a central place. The platforms which use
> specific machine drivers do the same and that is why probably the
> codec driver patch was never required. It is about just setting MCLK
> clock as a factor of sample rate, whenever the factor is available. I
> understand that it is breaking your use case, but I am not sure if the
> usage of set_sysclk() is consistent. I mean, it takes the "freq"
> argument. Does it refer to MCLK rate or system-clock (sysclk) rate?
> MCLK and sysclk are not really the same when codec PLL is involved. So
> I would like to understand clearly about what "freq" argument means.
> Also when "mclk-fs" factor is specified, is it related to MCLK or
> sysclk? My understanding is that it should be strictly viewed as
> related to MCLK.
>
>
> Does it help if a separate helper is used for audio-graph-card with
> current change and reverting the simple-card to its previous state?
> Morimoto-san, does it affect any other users of audio-graph-card?
>
>>
>> I've also looked at other users of "simple-audio-card" and
>> it looks like they will break too. For example,
>> - arch/arm64/boot/dts/rockchip/rk3399.dtsi
>> If I'm not mistaken, this will try to set the first clock
>> of hdmi@ff940000 there, which is "iahb".
>> - arch/arm/boot/dts/sun8i-a33.dtsi
>> There "&ccu CLK_BUS_CODEC" of codec@1c22e00 will be changed
>>
>> And it doesn't stop there, it also sets the first clock
>> of the CPU endpoint, which I guess just works because .set_rate
>> is a noop for the most clocks which are used there.
>
> Yes this is a problem, unfortunately I missed checking some of the
> simple-card examples. I wonder we should be specifically looking for
> "mclk" clock here.
next prev parent reply other threads:[~2021-03-15 15:35 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-10 6:43 [PATCH 0/3] Use clocks property in a device node Sameer Pujar
2021-02-10 6:43 ` [PATCH 1/3] ASoC: simple-card-utils: Fix device module clock Sameer Pujar
2021-02-11 23:44 ` Kuninori Morimoto
2021-02-14 17:56 ` Sameer Pujar
2021-02-14 23:25 ` Kuninori Morimoto
2021-03-09 14:41 ` Michael Walle
2021-03-09 16:27 ` Sameer Pujar
2021-03-09 22:30 ` Michael Walle
2021-03-10 14:50 ` Sameer Pujar
2021-03-10 18:14 ` Michael Walle
2021-03-10 19:19 ` Sameer Pujar
2021-03-11 10:27 ` Michael Walle
2021-03-11 11:05 ` Sameer Pujar
2021-03-11 11:16 ` Michael Walle
2021-03-11 14:29 ` Sameer Pujar
2021-03-11 15:43 ` Michael Walle
2021-03-11 16:41 ` Mark Brown
2021-03-11 16:15 ` Mark Brown
2021-03-11 22:11 ` Michael Walle
2021-03-12 11:35 ` Mark Brown
2021-03-12 12:01 ` Michael Walle
2021-03-12 12:04 ` Mark Brown
2021-03-12 12:30 ` Michael Walle
2021-03-12 13:46 ` Mark Brown
2021-03-15 12:05 ` Michael Walle
2021-03-15 15:19 ` Sameer Pujar
2021-03-15 15:33 ` Michael Walle [this message]
2021-03-15 15:57 ` Sameer Pujar
2021-03-15 15:39 ` Mark Brown
2021-03-15 17:10 ` Sameer Pujar
2021-03-15 17:13 ` Michael Walle
2021-03-11 16:00 ` Mark Brown
2021-03-11 21:34 ` Michael Walle
2021-02-10 6:43 ` [PATCH 2/3] Revert "ASoC: audio-graph-card: Add clocks property to endpoint node" Sameer Pujar
2021-02-11 13:00 ` Mark Brown
2021-02-10 6:43 ` [PATCH 3/3] arm64: tegra: Move clocks from RT5658 endpoint to device node Sameer Pujar
2021-02-11 15:38 ` [PATCH 0/3] Use clocks property in a " Mark Brown
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