[PATCH 0/2] ASoC: Extended SPDIF support to Allwinner A31 SoCs

[PATCH 0/2] ASoC: Extended SPDIF support to Allwinner A31 SoCs

[codekipper]

From: Marcus Cooper <codekipper@gmail.com>

This patch set extends the current support of the Allwinner SPDIF
transceiver to include the A31 SoC.

For now just the SPDIF transmitter has been tested on the Mele I7.

In order for this patch set to be functional then we require changes
to the clocks and the device tree. For those that are interested I've
pushed all the required patches here

https://github.com/codekipper/linux-sunxi/commits/a31-spdif

Thanks in advance,
CK

Marcus Cooper (2):
  ASoC: sunxi: Add bindings for sun6i to SPDIF
  ASoC: sunxi: compatibility for sun6i to SPDIF

 .../devicetree/bindings/sound/sunxi,sun4i-spdif.txt     |  3 +++
 sound/soc/sunxi/sun4i-spdif.c                           | 17 ++++++++++++++++-
 2 files changed, 19 insertions(+), 1 deletion(-)

-- 
2.9.2

[PATCH 1/2] ASoC: sunxi: Add bindings for sun6i to SPDIF

[codekipper]

From: Marcus Cooper <codekipper@gmail.com>

The A31 SoC uses the same SPDIF block as found in earlier SoCs, but its
reset is controlled via a separate reset controller.

Signed-off-by: Marcus Cooper <codekipper@gmail.com>
---
 Documentation/devicetree/bindings/sound/sunxi,sun4i-spdif.txt | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/Documentation/devicetree/bindings/sound/sunxi,sun4i-spdif.txt b/Documentation/devicetree/bindings/sound/sunxi,sun4i-spdif.txt
index 13503aa..4fe80f7 100644
--- a/Documentation/devicetree/bindings/sound/sunxi,sun4i-spdif.txt
+++ b/Documentation/devicetree/bindings/sound/sunxi,sun4i-spdif.txt
@@ -9,6 +9,7 @@ Required properties:
 
   - compatible		: should be one of the following:
     - "allwinner,sun4i-a10-spdif": for the Allwinner A10 SoC
+    - "allwinner,sun6i-a31-spdif": for the Allwinner A31 SoC
 
   - reg			: Offset and length of the register set for the device.
 
@@ -25,6 +26,8 @@ Required properties:
 	"apb"		  clock for the spdif bus.
 	"spdif"		  clock for spdif controller.
 
+  - reset		: reset specifier for the ahb reset (A31 and newer only)
+
 Example:
 
 spdif: spdif@01c21000 {
-- 
2.9.2

[PATCH 2/2] ASoC: sunxi: compatibility for sun6i to SPDIF

[codekipper]

From: Marcus Cooper <codekipper@gmail.com>

The A31 SoC uses the same SPDIF block as found in earlier SoCs, but its
reset is controlled via a separate reset controller.

The DMA also complains when the maxburst is set to 4 so it's been adjusted
to 8 which suites both the older and newer SoCs.

Signed-off-by: Marcus Cooper <codekipper@gmail.com>
---
 sound/soc/sunxi/sun4i-spdif.c | 17 ++++++++++++++++-
 1 file changed, 16 insertions(+), 1 deletion(-)

diff --git a/sound/soc/sunxi/sun4i-spdif.c b/sound/soc/sunxi/sun4i-spdif.c
index 0b04fb0..88fbb3a 100644
--- a/sound/soc/sunxi/sun4i-spdif.c
+++ b/sound/soc/sunxi/sun4i-spdif.c
@@ -29,6 +29,7 @@
 #include <linux/module.h>
 #include <linux/platform_device.h>
 #include <linux/pm_runtime.h>
+#include <linux/reset.h>
 #include <sound/dmaengine_pcm.h>
 #include <sound/pcm_params.h>
 #include <sound/soc.h>
@@ -162,6 +163,7 @@ struct sun4i_spdif_dev {
 	struct platform_device *pdev;
 	struct clk *spdif_clk;
 	struct clk *apb_clk;
+	struct reset_control *rst;
 	struct snd_soc_dai_driver cpu_dai_drv;
 	struct regmap *regmap;
 	struct snd_dmaengine_dai_dma_data dma_params_tx;
@@ -411,6 +413,7 @@ static const struct snd_soc_dapm_route dit_routes[] = {
 
 static const struct of_device_id sun4i_spdif_of_match[] = {
 	{ .compatible = "allwinner,sun4i-a10-spdif", },
+	{ .compatible = "allwinner,sun6i-a31-spdif", },
 	{ /* sentinel */ }
 };
 MODULE_DEVICE_TABLE(of, sun4i_spdif_of_match);
@@ -482,11 +485,23 @@ static int sun4i_spdif_probe(struct platform_device *pdev)
 	}
 
 	host->dma_params_tx.addr = res->start + SUN4I_SPDIF_TXFIFO;
-	host->dma_params_tx.maxburst = 4;
+	host->dma_params_tx.maxburst = 8;
 	host->dma_params_tx.addr_width = DMA_SLAVE_BUSWIDTH_2_BYTES;
 
 	platform_set_drvdata(pdev, host);
 
+	if (of_device_is_compatible(pdev->dev.of_node,
+				    "allwinner,sun6i-a31-spdif")) {
+		host->rst = devm_reset_control_get_optional(&pdev->dev, NULL);
+		if (IS_ERR(host->rst) && PTR_ERR(host->rst) == -EPROBE_DEFER) {
+			ret = -EPROBE_DEFER;
+			dev_err(&pdev->dev, "Failed to get reset: %d\n", ret);
+			goto err_disable_apb_clk;
+		}
+		if (!IS_ERR(host->rst))
+			reset_control_deassert(host->rst);
+	}
+
 	ret = devm_snd_soc_register_component(&pdev->dev,
 				&sun4i_spdif_component, &sun4i_spdif_dai, 1);
 	if (ret)
-- 
2.9.2

Re: [linux-sunxi] [PATCH 2/2] ASoC: sunxi: compatibility for sun6i to SPDIF

[Julian Calaby]

Hi Marcus,

On Sun, Jul 31, 2016 at 12:27 AM,  <codekipper@gmail.com> wrote:
> From: Marcus Cooper <codekipper@gmail.com>
>
> The A31 SoC uses the same SPDIF block as found in earlier SoCs, but its
> reset is controlled via a separate reset controller.
>
> The DMA also complains when the maxburst is set to 4 so it's been adjusted
> to 8 which suites both the older and newer SoCs.
>
> Signed-off-by: Marcus Cooper <codekipper@gmail.com>
> ---
>  sound/soc/sunxi/sun4i-spdif.c | 17 ++++++++++++++++-
>  1 file changed, 16 insertions(+), 1 deletion(-)
>
> diff --git a/sound/soc/sunxi/sun4i-spdif.c b/sound/soc/sunxi/sun4i-spdif.c
> index 0b04fb0..88fbb3a 100644
> --- a/sound/soc/sunxi/sun4i-spdif.c
> +++ b/sound/soc/sunxi/sun4i-spdif.c
> @@ -482,11 +485,23 @@ static int sun4i_spdif_probe(struct platform_device *pdev)
>         }
>
>         host->dma_params_tx.addr = res->start + SUN4I_SPDIF_TXFIFO;
> -       host->dma_params_tx.maxburst = 4;
> +       host->dma_params_tx.maxburst = 8;
>         host->dma_params_tx.addr_width = DMA_SLAVE_BUSWIDTH_2_BYTES;
>
>         platform_set_drvdata(pdev, host);
>
> +       if (of_device_is_compatible(pdev->dev.of_node,
> +                                   "allwinner,sun6i-a31-spdif")) {

Given how much Allwinner likes to shuffle stuff around with each SoC
generation, would it make sense to add a flag for this in some
compatible specific config structure instead of checking against the
compatible?

Thanks,

-- 
Julian Calaby

Email: julian.calaby@gmail.com
Profile: http://www.google.com/profiles/julian.calaby/

Re: [PATCH 1/2] ASoC: sunxi: Add bindings for sun6i to SPDIF

[Maxime Ripard]

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On Sat, Jul 30, 2016 at 04:27:15PM +0200, codekipper@gmail.com wrote:
> From: Marcus Cooper <codekipper@gmail.com>
> 
> The A31 SoC uses the same SPDIF block as found in earlier SoCs, but its
> reset is controlled via a separate reset controller.
> 
> Signed-off-by: Marcus Cooper <codekipper@gmail.com>
> ---
>  Documentation/devicetree/bindings/sound/sunxi,sun4i-spdif.txt | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/sound/sunxi,sun4i-spdif.txt b/Documentation/devicetree/bindings/sound/sunxi,sun4i-spdif.txt
> index 13503aa..4fe80f7 100644
> --- a/Documentation/devicetree/bindings/sound/sunxi,sun4i-spdif.txt
> +++ b/Documentation/devicetree/bindings/sound/sunxi,sun4i-spdif.txt
> @@ -9,6 +9,7 @@ Required properties:
>  
>    - compatible		: should be one of the following:
>      - "allwinner,sun4i-a10-spdif": for the Allwinner A10 SoC
> +    - "allwinner,sun6i-a31-spdif": for the Allwinner A31 SoC
>  
>    - reg			: Offset and length of the register set for the device.
>  
> @@ -25,6 +26,8 @@ Required properties:
>  	"apb"		  clock for the spdif bus.
>  	"spdif"		  clock for spdif controller.
>  
> +  - reset		: reset specifier for the ahb reset (A31 and newer only)

Isn't it resets ? (plural)

Thanks,
Maxime

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

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Re: [PATCH 2/2] ASoC: sunxi: compatibility for sun6i to SPDIF

[Maxime Ripard]

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On Sat, Jul 30, 2016 at 04:27:16PM +0200, codekipper@gmail.com wrote:
> From: Marcus Cooper <codekipper@gmail.com>
> 
> The A31 SoC uses the same SPDIF block as found in earlier SoCs, but its
> reset is controlled via a separate reset controller.
> 
> The DMA also complains when the maxburst is set to 4 so it's been adjusted
> to 8 which suites both the older and newer SoCs.
> 
> Signed-off-by: Marcus Cooper <codekipper@gmail.com>

Acked-by: Maxime Ripard <maxime.ripard@free-electrons.com>

Thanks,
Maxime

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

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Re: [PATCH 2/2] ASoC: sunxi: compatibility for sun6i to SPDIF

[maxime.ripard]

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On Sat, Jul 30, 2016 at 10:52:45PM +0800, Icenowy Zheng wrote:
> > + if (of_device_is_compatible(pdev->dev.of_node,
> > + "allwinner,sun6i-a31-spdif")) {
> > + host->rst = devm_reset_control_get_optional(&pdev->dev, NULL);
> > + if (IS_ERR(host->rst) && PTR_ERR(host->rst) == -EPROBE_DEFER) {
> > + ret = -EPROBE_DEFER;
> > + dev_err(&pdev->dev, "Failed to get reset: %d\n", ret);
> > + goto err_disable_apb_clk;
> > + }
> > + if (!IS_ERR(host->rst))
> > + reset_control_deassert(host->rst);
> > + }
> > +
> I think you do not need the compatible.
> You can just detect whether the reset is present.

That would weaken the error check. If we're running on the A31 and are
missing our reset property, it would go unnoticed.

Maxime

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

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Re: [linux-sunxi] [PATCH 2/2] ASoC: sunxi: compatibility for sun6i to SPDIF

[Maxime Ripard]

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On Sun, Jul 31, 2016 at 12:40:48AM +1000, Julian Calaby wrote:
> Hi Marcus,
> 
> On Sun, Jul 31, 2016 at 12:27 AM,  <codekipper@gmail.com> wrote:
> > From: Marcus Cooper <codekipper@gmail.com>
> >
> > The A31 SoC uses the same SPDIF block as found in earlier SoCs, but its
> > reset is controlled via a separate reset controller.
> >
> > The DMA also complains when the maxburst is set to 4 so it's been adjusted
> > to 8 which suites both the older and newer SoCs.
> >
> > Signed-off-by: Marcus Cooper <codekipper@gmail.com>
> > ---
> >  sound/soc/sunxi/sun4i-spdif.c | 17 ++++++++++++++++-
> >  1 file changed, 16 insertions(+), 1 deletion(-)
> >
> > diff --git a/sound/soc/sunxi/sun4i-spdif.c b/sound/soc/sunxi/sun4i-spdif.c
> > index 0b04fb0..88fbb3a 100644
> > --- a/sound/soc/sunxi/sun4i-spdif.c
> > +++ b/sound/soc/sunxi/sun4i-spdif.c
> > @@ -482,11 +485,23 @@ static int sun4i_spdif_probe(struct platform_device *pdev)
> >         }
> >
> >         host->dma_params_tx.addr = res->start + SUN4I_SPDIF_TXFIFO;
> > -       host->dma_params_tx.maxburst = 4;
> > +       host->dma_params_tx.maxburst = 8;
> >         host->dma_params_tx.addr_width = DMA_SLAVE_BUSWIDTH_2_BYTES;
> >
> >         platform_set_drvdata(pdev, host);
> >
> > +       if (of_device_is_compatible(pdev->dev.of_node,
> > +                                   "allwinner,sun6i-a31-spdif")) {
> 
> Given how much Allwinner likes to shuffle stuff around with each SoC
> generation, would it make sense to add a flag for this in some
> compatible specific config structure instead of checking against the
> compatible?

It really depends on the size of the quirks you have to maintain. If
it's just a single one like here, I'd say it's less of a hassle (and
actually easier and conciser to implement).

Maxime

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

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Re: [PATCH 1/2] ASoC: sunxi: Add bindings for sun6i to SPDIF

[Code Kipper]

On 30 July 2016 at 17:17, Maxime Ripard
<maxime.ripard@free-electrons.com> wrote:
> On Sat, Jul 30, 2016 at 04:27:15PM +0200, codekipper@gmail.com wrote:
>> From: Marcus Cooper <codekipper@gmail.com>
>>
>> The A31 SoC uses the same SPDIF block as found in earlier SoCs, but its
>> reset is controlled via a separate reset controller.
>>
>> Signed-off-by: Marcus Cooper <codekipper@gmail.com>
>> ---
>>  Documentation/devicetree/bindings/sound/sunxi,sun4i-spdif.txt | 3 +++
>>  1 file changed, 3 insertions(+)
>>
>> diff --git a/Documentation/devicetree/bindings/sound/sunxi,sun4i-spdif.txt b/Documentation/devicetree/bindings/sound/sunxi,sun4i-spdif.txt
>> index 13503aa..4fe80f7 100644
>> --- a/Documentation/devicetree/bindings/sound/sunxi,sun4i-spdif.txt
>> +++ b/Documentation/devicetree/bindings/sound/sunxi,sun4i-spdif.txt
>> @@ -9,6 +9,7 @@ Required properties:
>>
>>    - compatible               : should be one of the following:
>>      - "allwinner,sun4i-a10-spdif": for the Allwinner A10 SoC
>> +    - "allwinner,sun6i-a31-spdif": for the Allwinner A31 SoC
>>
>>    - reg                      : Offset and length of the register set for the device.
>>
>> @@ -25,6 +26,8 @@ Required properties:
>>       "apb"             clock for the spdif bus.
>>       "spdif"           clock for spdif controller.
>>
>> +  - reset            : reset specifier for the ahb reset (A31 and newer only)
>
> Isn't it resets ? (plural)

Dohh..yes it is. Do you want me to send an updated patch series, a
single patch change or could I beg for your commit massaging?
Thanks,
CK
>
> Thanks,
> Maxime
>
> --
> Maxime Ripard, Free Electrons
> Embedded Linux and Kernel engineering
> http://free-electrons.com

Re: [PATCH 1/2] ASoC: sunxi: Add bindings for sun6i to SPDIF

[Maxime Ripard]

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On Sat, Jul 30, 2016 at 05:34:11PM +0200, Code Kipper wrote:
> On 30 July 2016 at 17:17, Maxime Ripard
> <maxime.ripard@free-electrons.com> wrote:
> > On Sat, Jul 30, 2016 at 04:27:15PM +0200, codekipper@gmail.com wrote:
> >> From: Marcus Cooper <codekipper@gmail.com>
> >>
> >> The A31 SoC uses the same SPDIF block as found in earlier SoCs, but its
> >> reset is controlled via a separate reset controller.
> >>
> >> Signed-off-by: Marcus Cooper <codekipper@gmail.com>
> >> ---
> >>  Documentation/devicetree/bindings/sound/sunxi,sun4i-spdif.txt | 3 +++
> >>  1 file changed, 3 insertions(+)
> >>
> >> diff --git a/Documentation/devicetree/bindings/sound/sunxi,sun4i-spdif.txt b/Documentation/devicetree/bindings/sound/sunxi,sun4i-spdif.txt
> >> index 13503aa..4fe80f7 100644
> >> --- a/Documentation/devicetree/bindings/sound/sunxi,sun4i-spdif.txt
> >> +++ b/Documentation/devicetree/bindings/sound/sunxi,sun4i-spdif.txt
> >> @@ -9,6 +9,7 @@ Required properties:
> >>
> >>    - compatible               : should be one of the following:
> >>      - "allwinner,sun4i-a10-spdif": for the Allwinner A10 SoC
> >> +    - "allwinner,sun6i-a31-spdif": for the Allwinner A31 SoC
> >>
> >>    - reg                      : Offset and length of the register set for the device.
> >>
> >> @@ -25,6 +26,8 @@ Required properties:
> >>       "apb"             clock for the spdif bus.
> >>       "spdif"           clock for spdif controller.
> >>
> >> +  - reset            : reset specifier for the ahb reset (A31 and newer only)
> >
> > Isn't it resets ? (plural)
> 
> Dohh..yes it is. Do you want me to send an updated patch series, a
> single patch change or could I beg for your commit massaging?

I'm not the one who is going to apply that patch, so I don't know :)

Maxime

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

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Re: [linux-sunxi] Re: [PATCH 2/2] ASoC: sunxi: compatibility for sun6i to SPDIF

[Chen-Yu Tsai]

Hi,

On Sat, Jul 30, 2016 at 11:20 PM, maxime.ripard@free-electrons.com
<maxime.ripard@free-electrons.com> wrote:
> On Sat, Jul 30, 2016 at 10:52:45PM +0800, Icenowy Zheng wrote:
>> > + if (of_device_is_compatible(pdev->dev.of_node,
>> > + "allwinner,sun6i-a31-spdif")) {
>> > + host->rst = devm_reset_control_get_optional(&pdev->dev, NULL);
>> > + if (IS_ERR(host->rst) && PTR_ERR(host->rst) == -EPROBE_DEFER) {
>> > + ret = -EPROBE_DEFER;
>> > + dev_err(&pdev->dev, "Failed to get reset: %d\n", ret);
>> > + goto err_disable_apb_clk;
>> > + }
>> > + if (!IS_ERR(host->rst))
>> > + reset_control_deassert(host->rst);
>> > + }
>> > +
>> I think you do not need the compatible.
>> You can just detect whether the reset is present.
>
> That would weaken the error check. If we're running on the A31 and are
> missing our reset property, it would go unnoticed.

We've been doing it this way with the mmc controller and the usb hosts though.
IIRC you once said in the older SoCs, the reset control is tied to the clock
gate in the hardware.

The _optional variant is also funny, though I understand it is a design
of the reset controller framework.


Regards
ChenYu

Applied "ASoC: sunxi: compatibility for sun6i to SPDIF" to the asoc tree

[Mark Brown]

The patch

   ASoC: sunxi: compatibility for sun6i to SPDIF

has been applied to the asoc tree at

   git://git.kernel.org/pub/scm/linux/kernel/git/broonie/sound.git 

All being well this means that it will be integrated into the linux-next
tree (usually sometime in the next 24 hours) and sent to Linus during
the next merge window (or sooner if it is a bug fix), however if
problems are discovered then the patch may be dropped or reverted.  

You may get further e-mails resulting from automated or manual testing
and review of the tree, please engage with people reporting problems and
send followup patches addressing any issues that are reported if needed.

If any updates are required or you are submitting further changes they
should be sent as incremental updates against current git, existing
patches will not be replaced.

Please add any relevant lists and maintainers to the CCs when replying
to this mail.

Thanks,
Mark

>From 2f6963cb52bee440105f732b3411f18e38ed6e52 Mon Sep 17 00:00:00 2001
From: Marcus Cooper <codekipper@gmail.com>
Date: Sat, 30 Jul 2016 17:56:38 +0200
Subject: [PATCH] ASoC: sunxi: compatibility for sun6i to SPDIF

The A31 SoC uses the same SPDIF block as found in earlier SoCs, but its
reset is controlled via a separate reset controller.

The DMA also complains when the maxburst is set to 4 so it's been adjusted
to 8 which suites both the older and newer SoCs.

Signed-off-by: Marcus Cooper <codekipper@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
---
 sound/soc/sunxi/sun4i-spdif.c | 17 ++++++++++++++++-
 1 file changed, 16 insertions(+), 1 deletion(-)

diff --git a/sound/soc/sunxi/sun4i-spdif.c b/sound/soc/sunxi/sun4i-spdif.c
index 0b04fb02125c..88fbb3a1e660 100644
--- a/sound/soc/sunxi/sun4i-spdif.c
+++ b/sound/soc/sunxi/sun4i-spdif.c
@@ -29,6 +29,7 @@
 #include <linux/module.h>
 #include <linux/platform_device.h>
 #include <linux/pm_runtime.h>
+#include <linux/reset.h>
 #include <sound/dmaengine_pcm.h>
 #include <sound/pcm_params.h>
 #include <sound/soc.h>
@@ -162,6 +163,7 @@ struct sun4i_spdif_dev {
 	struct platform_device *pdev;
 	struct clk *spdif_clk;
 	struct clk *apb_clk;
+	struct reset_control *rst;
 	struct snd_soc_dai_driver cpu_dai_drv;
 	struct regmap *regmap;
 	struct snd_dmaengine_dai_dma_data dma_params_tx;
@@ -411,6 +413,7 @@ static const struct snd_soc_dapm_route dit_routes[] = {
 
 static const struct of_device_id sun4i_spdif_of_match[] = {
 	{ .compatible = "allwinner,sun4i-a10-spdif", },
+	{ .compatible = "allwinner,sun6i-a31-spdif", },
 	{ /* sentinel */ }
 };
 MODULE_DEVICE_TABLE(of, sun4i_spdif_of_match);
@@ -482,11 +485,23 @@ static int sun4i_spdif_probe(struct platform_device *pdev)
 	}
 
 	host->dma_params_tx.addr = res->start + SUN4I_SPDIF_TXFIFO;
-	host->dma_params_tx.maxburst = 4;
+	host->dma_params_tx.maxburst = 8;
 	host->dma_params_tx.addr_width = DMA_SLAVE_BUSWIDTH_2_BYTES;
 
 	platform_set_drvdata(pdev, host);
 
+	if (of_device_is_compatible(pdev->dev.of_node,
+				    "allwinner,sun6i-a31-spdif")) {
+		host->rst = devm_reset_control_get_optional(&pdev->dev, NULL);
+		if (IS_ERR(host->rst) && PTR_ERR(host->rst) == -EPROBE_DEFER) {
+			ret = -EPROBE_DEFER;
+			dev_err(&pdev->dev, "Failed to get reset: %d\n", ret);
+			goto err_disable_apb_clk;
+		}
+		if (!IS_ERR(host->rst))
+			reset_control_deassert(host->rst);
+	}
+
 	ret = devm_snd_soc_register_component(&pdev->dev,
 				&sun4i_spdif_component, &sun4i_spdif_dai, 1);
 	if (ret)
-- 
2.8.1

Re: [linux-sunxi] Re: [PATCH 2/2] ASoC: sunxi: compatibility for sun6i to SPDIF

[Maxime Ripard]

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Hi,

On Mon, Aug 01, 2016 at 09:39:34PM +0800, Chen-Yu Tsai wrote:
> Hi,
> 
> On Sat, Jul 30, 2016 at 11:20 PM, maxime.ripard@free-electrons.com
> <maxime.ripard@free-electrons.com> wrote:
> > On Sat, Jul 30, 2016 at 10:52:45PM +0800, Icenowy Zheng wrote:
> >> > + if (of_device_is_compatible(pdev->dev.of_node,
> >> > + "allwinner,sun6i-a31-spdif")) {
> >> > + host->rst = devm_reset_control_get_optional(&pdev->dev, NULL);
> >> > + if (IS_ERR(host->rst) && PTR_ERR(host->rst) == -EPROBE_DEFER) {
> >> > + ret = -EPROBE_DEFER;
> >> > + dev_err(&pdev->dev, "Failed to get reset: %d\n", ret);
> >> > + goto err_disable_apb_clk;
> >> > + }
> >> > + if (!IS_ERR(host->rst))
> >> > + reset_control_deassert(host->rst);
> >> > + }
> >> > +
> >> I think you do not need the compatible.
> >> You can just detect whether the reset is present.
> >
> > That would weaken the error check. If we're running on the A31 and are
> > missing our reset property, it would go unnoticed.
> 
> We've been doing it this way with the mmc controller and the usb hosts though.
> IIRC you once said in the older SoCs, the reset control is tied to the clock
> gate in the hardware.
> 
> The _optional variant is also funny, though I understand it is a design
> of the reset controller framework.

Yes, I know. But that doesn't prevent that design from being better.

Maxime

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

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