[PATCH 0/2] rockchip: i2s: patches to add optional clock output from

[PATCH 0/2] rockchip: i2s: patches to add optional clock output from

[Jianqun Xu]

The clock output from rockchip SoCs' CRU to chip outside is from the same source
as hclk which is for i2s controller. We make it optional because some audio
codec outside not need the master clock from SoC but from other clock source.

Jianqun Xu (2):
  ASoC: rockchip-i2s: dt: add an optional property "i2s_clk_out"
  ASoC: rockchip: i2s: add support for grabbing output clock to codec

 Documentation/devicetree/bindings/sound/rockchip-i2s.txt |  8 ++++++--
 sound/soc/rockchip/rockchip_i2s.c                        | 11 +++++++++++
 2 files changed, 17 insertions(+), 2 deletions(-)

-- 
1.9.1

[PATCH 1/2] ASoC: rockchip-i2s: dt: add an optional property "i2s_clk_out"

[Jianqun Xu]

Add an property "i2s_clk_out", which enables to output clock to outside
of rockchip SoCs. Let's make it optional since not each board needs it.

Signed-off-by: Jianqun Xu <jay.xu@rock-chips.com>
---
 Documentation/devicetree/bindings/sound/rockchip-i2s.txt | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/Documentation/devicetree/bindings/sound/rockchip-i2s.txt b/Documentation/devicetree/bindings/sound/rockchip-i2s.txt
index 9b82c20..c8f5ac0 100644
--- a/Documentation/devicetree/bindings/sound/rockchip-i2s.txt
+++ b/Documentation/devicetree/bindings/sound/rockchip-i2s.txt
@@ -22,6 +22,10 @@ Required properties:
    - "i2s_hclk": clock for I2S BUS
    - "i2s_clk" : clock for I2S controller
 
+Optional property:
+- "i2s_clk_out" : clock output to outside of chip, usally as master clock for audio
+	codec chip
+
 Example for rk3288 I2S controller:
 
 i2s@ff890000 {
@@ -32,6 +36,6 @@ i2s@ff890000 {
 	#size-cells = <0>;
 	dmas = <&pdma1 0>, <&pdma1 1>;
 	dma-names = "tx", "rx";
-	clock-names = "i2s_hclk", "i2s_clk";
-	clocks = <&cru HCLK_I2S0>, <&cru SCLK_I2S0>;
+	clock-names = "i2s_hclk", "i2s_clk", "i2s_clk_out";
+	clocks = <&cru HCLK_I2S0>, <&cru SCLK_I2S0>, <&cru SCLK_I2S0_CLKOUT>;
 };
-- 
1.9.1

Re: [PATCH 1/2] ASoC: rockchip-i2s: dt: add an optional property "i2s_clk_out"

[Doug Anderson]

Jianqun,

On Tue, Dec 2, 2014 at 6:49 AM, Jianqun Xu <jay.xu@rock-chips.com> wrote:
> Add an property "i2s_clk_out", which enables to output clock to outside
> of rockchip SoCs. Let's make it optional since not each board needs it.
>
> Signed-off-by: Jianqun Xu <jay.xu@rock-chips.com>
> ---
>  Documentation/devicetree/bindings/sound/rockchip-i2s.txt | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)

You forgot to mention that this is a v3 in the subject line and forgot
to mention what changed between v2 and v3 (nothing changed, but you
should say that).

Despite that, this patch looks reasonable to me.

Reviewed-by: Doug Anderson <dianders@chromium.org>

[PATCH 2/2] ASoC: rockchip: i2s: add support for grabbing output clock to codec

[Jianqun Xu]

From: Sonny Rao <sonnyrao@chromium.org>

We need to claim the clock which is driving the codec so that when we enable
clock gating, we continue to clock the codec when needed.  I make this an
optional clock since there might be some applications where we don't need it
but can still use the I2S block.

Signed-off-by: Sonny Rao <sonnyrao@chromium.org>
---
 sound/soc/rockchip/rockchip_i2s.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/sound/soc/rockchip/rockchip_i2s.c b/sound/soc/rockchip/rockchip_i2s.c
index c74ba37..2820ade 100644
--- a/sound/soc/rockchip/rockchip_i2s.c
+++ b/sound/soc/rockchip/rockchip_i2s.c
@@ -28,6 +28,7 @@ struct rk_i2s_dev {
 
 	struct clk *hclk;
 	struct clk *mclk;
+	struct clk *oclk;
 
 	struct snd_dmaengine_dai_dma_data capture_dma_data;
 	struct snd_dmaengine_dai_dma_data playback_dma_data;
@@ -439,6 +440,14 @@ static int rockchip_i2s_probe(struct platform_device *pdev)
 		return PTR_ERR(i2s->mclk);
 	}
 
+	i2s->oclk = devm_clk_get(&pdev->dev, "i2s_clk_out");
+	if (IS_ERR(i2s->oclk)) {
+		dev_dbg(&pdev->dev, "Didn't find output clock\n");
+		i2s->oclk = NULL;
+	}
+	if (i2s->oclk)
+		ret = clk_prepare_enable(i2s->oclk);
+
 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	regs = devm_ioremap_resource(&pdev->dev, res);
 	if (IS_ERR(regs))
@@ -505,6 +514,8 @@ static int rockchip_i2s_remove(struct platform_device *pdev)
 	if (!pm_runtime_status_suspended(&pdev->dev))
 		i2s_runtime_suspend(&pdev->dev);
 
+	if (i2s->oclk)
+		clk_disable_unprepare(i2s->oclk);
 	clk_disable_unprepare(i2s->mclk);
 	clk_disable_unprepare(i2s->hclk);
 	snd_dmaengine_pcm_unregister(&pdev->dev);
-- 
1.9.1

Re: [PATCH 2/2] ASoC: rockchip: i2s: add support for grabbing output clock to codec

[Doug Anderson]

Jianqun,

This ought to be a "v3" patch and ideally ought to describe
differences from v2 (after the cut).  Please have Kever or Chris
review your next patch before sending it out since I think they are
familiar with the process.


On Tue, Dec 2, 2014 at 6:52 AM, Jianqun Xu <jay.xu@rock-chips.com> wrote:
> From: Sonny Rao <sonnyrao@chromium.org>
>
> We need to claim the clock which is driving the codec so that when we enable
> clock gating, we continue to clock the codec when needed.  I make this an
> optional clock since there might be some applications where we don't need it
> but can still use the I2S block.
>
> Signed-off-by: Sonny Rao <sonnyrao@chromium.org>

You still forgot your own signed-off-by.  Please try again.  See
<https://patchwork.kernel.org/patch/5334991/>


> +       i2s->oclk = devm_clk_get(&pdev->dev, "i2s_clk_out");
> +       if (IS_ERR(i2s->oclk)) {
> +               dev_dbg(&pdev->dev, "Didn't find output clock\n");
> +               i2s->oclk = NULL;
> +       }

You still forgot the blank line here requested by Heiko.  Please try
again.  See <https://patchwork.kernel.org/patch/5334991/>


> +       if (i2s->oclk)
> +               ret = clk_prepare_enable(i2s->oclk);
> +

Re: [PATCH 2/2] ASoC: rockchip: i2s: add support for grabbing output clock to codec

[Jianqun]

Hi Doug:

在 12/03/2014 01:54 AM, Doug Anderson 写道:
> Jianqun,
> 
> This ought to be a "v3" patch and ideally ought to describe
> differences from v2 (after the cut).  Please have Kever or Chris
> review your next patch before sending it out since I think they are
> familiar with the process.
> 
> 
> On Tue, Dec 2, 2014 at 6:52 AM, Jianqun Xu <jay.xu@rock-chips.com> wrote:
>> From: Sonny Rao <sonnyrao@chromium.org>
>>
>> We need to claim the clock which is driving the codec so that when we enable
>> clock gating, we continue to clock the codec when needed.  I make this an
>> optional clock since there might be some applications where we don't need it
>> but can still use the I2S block.
>>
>> Signed-off-by: Sonny Rao <sonnyrao@chromium.org>
> 
> You still forgot your own signed-off-by.  Please try again.  See
> <https://patchwork.kernel.org/patch/5334991/>
ok, I will add my signed-off-by
> 
> 
>> +       i2s->oclk = devm_clk_get(&pdev->dev, "i2s_clk_out");
>> +       if (IS_ERR(i2s->oclk)) {
>> +               dev_dbg(&pdev->dev, "Didn't find output clock\n");
>> +               i2s->oclk = NULL;
>> +       }
> 
> You still forgot the blank line here requested by Heiko.  Please try
> again.  See <https://patchwork.kernel.org/patch/5334991/>
Although I thought there needn't a blank ~, I wll add it next patch
> 
> 
>> +       if (i2s->oclk)
>> +               ret = clk_prepare_enable(i2s->oclk);
>> +
> 
> 
> 

-- 
Jianqun Xu

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Re: [PATCH 2/2] ASoC: rockchip: i2s: add support for grabbing output clock to codec

[Doug Anderson]

On Tue, Dec 2, 2014 at 5:03 PM, Jianqun <xjq@rock-chips.com> wrote:
> Hi Doug:
>
> 在 12/03/2014 01:54 AM, Doug Anderson 写道:
>> Jianqun,
>>
>> This ought to be a "v3" patch and ideally ought to describe
>> differences from v2 (after the cut).  Please have Kever or Chris
>> review your next patch before sending it out since I think they are
>> familiar with the process.

You still seem to be missing versions in your subject line and missing
info on what changed version to version.  The latest version you just
sent (v4?) is still missing it.

Unless Mark says so then I don't think you need to spin this series,
but please try to add that in the future.


>> You still forgot the blank line here requested by Heiko.  Please try
>> again.  See <https://patchwork.kernel.org/patch/5334991/>
> Although I thought there needn't a blank ~, I wll add it next patch

That would have been OK, but in that case you should have responded to
Heiko's patch and explained that you weren't taking his feedback (and
why you weren't).

-Doug

Re: [PATCH 2/2] ASoC: rockchip: i2s: add support for grabbing output clock to codec

[Mark Brown]

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On Tue, Dec 02, 2014 at 09:18:35PM -0800, Doug Anderson wrote:

> You still seem to be missing versions in your subject line and missing
> info on what changed version to version.  The latest version you just
> sent (v4?) is still missing it.

> Unless Mark says so then I don't think you need to spin this series,
> but please try to add that in the future.

Don't resubmit.  I actually don't care much about any of that stuff and
mostly ignore it unless the change set is saying something other than
"addressed review comments".

One thing you should avoid doing is posting new versions in reply to old
versions as has been done here, that just makes for a confusing and hard
to follow mail archive with new serieses buried in the middle of threads.

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[PATCH v2 0/2] ASoC: rockchip: i2s: driver could output "i2s-clk-out" optionally

[Jianqun Xu]

Clock generate unit in rockchip SoCs could generate clock named "i2s-clk-out"
separate from clock named "i2s-hclk", which is for i2s controller.

Since there may not need the "i2s-clk-out" outside, we make it optional in
driver, that could be decided in dts by add "i2s-clk-out" or not.

Tested on devices based on rk3288 with max98090 codec.

Jianqun Xu (1):
  ASoC: dt-bindings: rockchip-i2s: add an optional property
    "i2s_clk_out"

Sonny Rao (1):
  ASoC: rockchip: i2s: add support for grabbing output clock to codec

 Documentation/devicetree/bindings/sound/rockchip-i2s.txt |  8 ++++++--
 sound/soc/rockchip/rockchip_i2s.c                        | 13 +++++++++++++
 2 files changed, 19 insertions(+), 2 deletions(-)

--
changes since v1:
- rework with patches commit message, reference to old commit message of the
same related files.
- generate patch again by apply sonny's patch
- fix blank line in driver, suggested by Heiko and Doug, so add my owner
singed-off-by

1.9.1

[PATCH v2 1/2] ASoC: dt-bindings: rockchip-i2s: add an optional property "i2s_clk_out"

[Jianqun Xu]

Add an property "i2s_clk_out", which enables to output clock to outside
of rockchip SoCs. Let's make it optional since not each board needs it.

Signed-off-by: Jianqun Xu <jay.xu@rock-chips.com>
Reviewed-by: Doug Anderson <dianders@chromium.org>
---
 Documentation/devicetree/bindings/sound/rockchip-i2s.txt | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/Documentation/devicetree/bindings/sound/rockchip-i2s.txt b/Documentation/devicetree/bindings/sound/rockchip-i2s.txt
index 9b82c20..c8f5ac0 100644
--- a/Documentation/devicetree/bindings/sound/rockchip-i2s.txt
+++ b/Documentation/devicetree/bindings/sound/rockchip-i2s.txt
@@ -22,6 +22,10 @@ Required properties:
    - "i2s_hclk": clock for I2S BUS
    - "i2s_clk" : clock for I2S controller
 
+Optional property:
+- "i2s_clk_out" : clock output to outside of chip, usally as master clock for audio
+	codec chip
+
 Example for rk3288 I2S controller:
 
 i2s@ff890000 {
@@ -32,6 +36,6 @@ i2s@ff890000 {
 	#size-cells = <0>;
 	dmas = <&pdma1 0>, <&pdma1 1>;
 	dma-names = "tx", "rx";
-	clock-names = "i2s_hclk", "i2s_clk";
-	clocks = <&cru HCLK_I2S0>, <&cru SCLK_I2S0>;
+	clock-names = "i2s_hclk", "i2s_clk", "i2s_clk_out";
+	clocks = <&cru HCLK_I2S0>, <&cru SCLK_I2S0>, <&cru SCLK_I2S0_CLKOUT>;
 };
-- 
1.9.1

[PATCH v2 2/2] ASoC: rockchip: i2s: add support for grabbing output clock to codec

[Jianqun Xu]

From: Sonny Rao <sonnyrao@chromium.org>

We need to claim the clock which is driving the codec so that when we enable
clock gating, we continue to clock the codec when needed.  I make this an
optional clock since there might be some applications where we don't need it
but can still use the I2S block.

Signed-off-by: Sonny Rao <sonnyrao@chromium.org>
Signed-off-by: Jianqun Xu <jay.xu@rock-chips.com>
---
 sound/soc/rockchip/rockchip_i2s.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/sound/soc/rockchip/rockchip_i2s.c b/sound/soc/rockchip/rockchip_i2s.c
index c74ba37..fd144ac 100644
--- a/sound/soc/rockchip/rockchip_i2s.c
+++ b/sound/soc/rockchip/rockchip_i2s.c
@@ -28,6 +28,7 @@ struct rk_i2s_dev {
 
 	struct clk *hclk;
 	struct clk *mclk;
+	struct clk *oclk;
 
 	struct snd_dmaengine_dai_dma_data capture_dma_data;
 	struct snd_dmaengine_dai_dma_data playback_dma_data;
@@ -439,6 +440,15 @@ static int rockchip_i2s_probe(struct platform_device *pdev)
 		return PTR_ERR(i2s->mclk);
 	}
 
+	i2s->oclk = devm_clk_get(&pdev->dev, "i2s_clk_out");
+	if (IS_ERR(i2s->oclk)) {
+		dev_dbg(&pdev->dev, "Didn't find output clock\n");
+		i2s->oclk = NULL;
+	}
+
+	if (i2s->oclk)
+		ret = clk_prepare_enable(i2s->oclk);
+
 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	regs = devm_ioremap_resource(&pdev->dev, res);
 	if (IS_ERR(regs))
@@ -505,6 +515,9 @@ static int rockchip_i2s_remove(struct platform_device *pdev)
 	if (!pm_runtime_status_suspended(&pdev->dev))
 		i2s_runtime_suspend(&pdev->dev);
 
+	if (i2s->oclk)
+		clk_disable_unprepare(i2s->oclk);
+
 	clk_disable_unprepare(i2s->mclk);
 	clk_disable_unprepare(i2s->hclk);
 	snd_dmaengine_pcm_unregister(&pdev->dev);
-- 
1.9.1

Re: [PATCH v2 2/2] ASoC: rockchip: i2s: add support for grabbing output clock to codec

[Mark Brown]

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On Wed, Dec 03, 2014 at 03:18:38PM +0800, Jianqun Xu wrote:
> From: Sonny Rao <sonnyrao@chromium.org>
> 
> We need to claim the clock which is driving the codec so that when we enable
> clock gating, we continue to clock the codec when needed.  I make this an
> optional clock since there might be some applications where we don't need it
> but can still use the I2S block.

I would expect that the clock for the CODEC should be managed by the
CODEC if at all possible - that seems more logical than having the CPU
I2S controller request and manage it if it's a separate clock.  Why add
this to the CPU side driver?

We've not always done this for older systems due to the lack of a usable
clock API but that's starting to be addressed.

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Re: [PATCH v2 2/2] ASoC: rockchip: i2s: add support for grabbing output clock to codec

[Sonny Rao]

On Wed, Dec 3, 2014 at 11:20 AM, Mark Brown <broonie@kernel.org> wrote:
> On Wed, Dec 03, 2014 at 03:18:38PM +0800, Jianqun Xu wrote:
>> From: Sonny Rao <sonnyrao@chromium.org>
>>
>> We need to claim the clock which is driving the codec so that when we enable
>> clock gating, we continue to clock the codec when needed.  I make this an
>> optional clock since there might be some applications where we don't need it
>> but can still use the I2S block.
>
> I would expect that the clock for the CODEC should be managed by the
> CODEC if at all possible - that seems more logical than having the CPU
> I2S controller request and manage it if it's a separate clock.  Why add
> this to the CPU side driver?

It's a good question.  Right now the way I'm running this stuff we're
mostly setting all the i2s the clock rates from the codec driver, but
I think this isn't the correct way to go, and the i2s driver needs to
set it's rate based on the hw params, but that isn't happening (yet).

This output clock has a mux and can either be a fixed 12Mhz output or
can be derived from the same fractional divider which drives the i2s
block.   I thought it was simpler to keep them all the same, but need
to put ownership in the i2s in anticipation of the i2s driver setting
it's own clock rate.

If you think this is an implementation detail and this output clock
should just be owned by the codec driver, even though I'm guessing it
will just have to be the same as i2s, then I think we can drop this
and make sure simple card (or whatever other codec driver) claims this
clock.


>
> We've not always done this for older systems due to the lack of a usable
> clock API but that's starting to be addressed.

Re: [PATCH v2 2/2] ASoC: rockchip: i2s: add support for grabbing output clock to codec

[Mark Brown]

[-- Attachment #1: Type: text/plain, Size: 1325 bytes --]

On Wed, Dec 03, 2014 at 11:38:13AM -0800, Sonny Rao wrote:
> On Wed, Dec 3, 2014 at 11:20 AM, Mark Brown <broonie@kernel.org> wrote:

> > I would expect that the clock for the CODEC should be managed by the
> > CODEC if at all possible - that seems more logical than having the CPU
> > I2S controller request and manage it if it's a separate clock.  Why add
> > this to the CPU side driver?

> This output clock has a mux and can either be a fixed 12Mhz output or
> can be derived from the same fractional divider which drives the i2s
> block.   I thought it was simpler to keep them all the same, but need
> to put ownership in the i2s in anticipation of the i2s driver setting
> it's own clock rate.

> If you think this is an implementation detail and this output clock
> should just be owned by the codec driver, even though I'm guessing it
> will just have to be the same as i2s, then I think we can drop this
> and make sure simple card (or whatever other codec driver) claims this
> clock.

simple-card obviously isn't a CODEC driver...  For generality I think
the clock does need to be exposed to the CODEC driver, otherwise this
will work differently to how other systems are working and we can't
substitute in a different clock on the CODEC side so easily if it
doesn't happen to use the output from the I2S block.

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Re: [PATCH v2 2/2] ASoC: rockchip: i2s: add support for grabbing output clock to codec

[Sonny Rao]

On Wed, Dec 3, 2014 at 12:03 PM, Mark Brown <broonie@kernel.org> wrote:
> On Wed, Dec 03, 2014 at 11:38:13AM -0800, Sonny Rao wrote:
>> On Wed, Dec 3, 2014 at 11:20 AM, Mark Brown <broonie@kernel.org> wrote:
>
>> > I would expect that the clock for the CODEC should be managed by the
>> > CODEC if at all possible - that seems more logical than having the CPU
>> > I2S controller request and manage it if it's a separate clock.  Why add
>> > this to the CPU side driver?
>
>> This output clock has a mux and can either be a fixed 12Mhz output or
>> can be derived from the same fractional divider which drives the i2s
>> block.   I thought it was simpler to keep them all the same, but need
>> to put ownership in the i2s in anticipation of the i2s driver setting
>> it's own clock rate.
>
>> If you think this is an implementation detail and this output clock
>> should just be owned by the codec driver, even though I'm guessing it
>> will just have to be the same as i2s, then I think we can drop this
>> and make sure simple card (or whatever other codec driver) claims this
>> clock.
>
> simple-card obviously isn't a CODEC driver...

Yeah, sorry.

> For generality I think
> the clock does need to be exposed to the CODEC driver, otherwise this
> will work differently to how other systems are working and we can't
> substitute in a different clock on the CODEC side so easily if it
> doesn't happen to use the output from the I2S block.

Ok, then I think what we will do is abandon this patch and I will send
something that adds this functionality to the particular codec that
I'm interested in -- max98090.

I'm a little tied up at the moment so I'm not going to send that for a
little while, but will come eventually.

Thanks for the advice!

Re: [alsa-devel] [PATCH v2 2/2] ASoC: rockchip: i2s: add support for grabbing output clock to codec

[Dylan Reid]

On Wed, Dec 3, 2014 at 3:03 PM, Sonny Rao <sonnyrao@chromium.org> wrote:
> On Wed, Dec 3, 2014 at 12:03 PM, Mark Brown <broonie@kernel.org> wrote:
>> On Wed, Dec 03, 2014 at 11:38:13AM -0800, Sonny Rao wrote:
>>> On Wed, Dec 3, 2014 at 11:20 AM, Mark Brown <broonie@kernel.org> wrote:
>>
>>> > I would expect that the clock for the CODEC should be managed by the
>>> > CODEC if at all possible - that seems more logical than having the CPU
>>> > I2S controller request and manage it if it's a separate clock.  Why add
>>> > this to the CPU side driver?
>>
>>> This output clock has a mux and can either be a fixed 12Mhz output or
>>> can be derived from the same fractional divider which drives the i2s
>>> block.   I thought it was simpler to keep them all the same, but need
>>> to put ownership in the i2s in anticipation of the i2s driver setting
>>> it's own clock rate.
>>
>>> If you think this is an implementation detail and this output clock
>>> should just be owned by the codec driver, even though I'm guessing it
>>> will just have to be the same as i2s, then I think we can drop this
>>> and make sure simple card (or whatever other codec driver) claims this
>>> clock.
>>
>> simple-card obviously isn't a CODEC driver...
>
> Yeah, sorry.
>
>> For generality I think
>> the clock does need to be exposed to the CODEC driver, otherwise this
>> will work differently to how other systems are working and we can't
>> substitute in a different clock on the CODEC side so easily if it
>> doesn't happen to use the output from the I2S block.
>
> Ok, then I think what we will do is abandon this patch and I will send
> something that adds this functionality to the particular codec that
> I'm interested in -- max98090.

Sorry I didn't read this earlier.  I don't think that this belongs in
the max98090.  The original patch description is a bit confusing.  The
clock being grabbed here is actually i2s mclk.  My understanding is
that, on this SoC, the mclk is driven from a different IP block than
the rest of the i2s signals.  The i2s driver needs to be told about
the clock and enable/disable it at the appropriate times.  I'm
assuming it's optional because there are boards using this SoC with
i2s slave mode that don't drive mclk at all.

Please correct me if I'm wrong on any of the above.

Re: [alsa-devel] [PATCH v2 2/2] ASoC: rockchip: i2s: add support for grabbing output clock to codec

[Sonny Rao]

On Wed, Dec 3, 2014 at 3:22 PM, Dylan Reid <dgreid@chromium.org> wrote:
> On Wed, Dec 3, 2014 at 3:03 PM, Sonny Rao <sonnyrao@chromium.org> wrote:
>> On Wed, Dec 3, 2014 at 12:03 PM, Mark Brown <broonie@kernel.org> wrote:
>>> On Wed, Dec 03, 2014 at 11:38:13AM -0800, Sonny Rao wrote:
>>>> On Wed, Dec 3, 2014 at 11:20 AM, Mark Brown <broonie@kernel.org> wrote:
>>>
>>>> > I would expect that the clock for the CODEC should be managed by the
>>>> > CODEC if at all possible - that seems more logical than having the CPU
>>>> > I2S controller request and manage it if it's a separate clock.  Why add
>>>> > this to the CPU side driver?
>>>
>>>> This output clock has a mux and can either be a fixed 12Mhz output or
>>>> can be derived from the same fractional divider which drives the i2s
>>>> block.   I thought it was simpler to keep them all the same, but need
>>>> to put ownership in the i2s in anticipation of the i2s driver setting
>>>> it's own clock rate.
>>>
>>>> If you think this is an implementation detail and this output clock
>>>> should just be owned by the codec driver, even though I'm guessing it
>>>> will just have to be the same as i2s, then I think we can drop this
>>>> and make sure simple card (or whatever other codec driver) claims this
>>>> clock.
>>>
>>> simple-card obviously isn't a CODEC driver...
>>
>> Yeah, sorry.
>>
>>> For generality I think
>>> the clock does need to be exposed to the CODEC driver, otherwise this
>>> will work differently to how other systems are working and we can't
>>> substitute in a different clock on the CODEC side so easily if it
>>> doesn't happen to use the output from the I2S block.
>>
>> Ok, then I think what we will do is abandon this patch and I will send
>> something that adds this functionality to the particular codec that
>> I'm interested in -- max98090.
>
> Sorry I didn't read this earlier.  I don't think that this belongs in
> the max98090.  The original patch description is a bit confusing.  The
> clock being grabbed here is actually i2s mclk.  My understanding is
> that, on this SoC, the mclk is driven from a different IP block than
> the rest of the i2s signals.  The i2s driver needs to be told about
> the clock and enable/disable it at the appropriate times.  I'm
> assuming it's optional because there are boards using this SoC with
> i2s slave mode that don't drive mclk at all.
>
> Please correct me if I'm wrong on any of the above.

I don't think you're wrong, and I'm an audio/i2s neophyte so I think
you're probably right and hopefully Mark can confirm that this is how
we want it.

One important thing to point out, which might be causing confusion, is
that this driver is claiming a clock which it internally calls "mclk"
but the way it's specified for rk3288 in the DT, that one is just the
one which drives the internal logic and has a gate.

This clock I'm adding is the actual mclk which is being driven to the
i2s slave device, and it has it's own gate and also has a mux, and we
need to claim both to be able to enable proper clock gating.