[v2] ASoC: ti: omap-mcpdm: Add support for pdmclk clock handling

Message ID 20191025130528.3556-1-peter.ujfalusi@ti.com
State New
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Series
  • [v2] ASoC: ti: omap-mcpdm: Add support for pdmclk clock handling
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Commit Message

Peter Ujfalusi Oct. 25, 2019, 1:05 p.m.
McPDM module receives it's functional clock from external source. This
clock is the pdmclk provided by the twl6040 audio IC. If the clock is not
available all register accesses to McPDM fails and the module is not
operational.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>

Acked-by: Jarkko Nikula <jarkko.nikula@bitmer.com>

---
Hi,

this has been lurking in my next-wip branch for some time...
It might not needed anymore as I have not heard about issues with McPDM for a
while.

It was dropped back then because some core parts were not picked in time and
this caused some issues, but can not find the exact reason

Regards,
Peter

 sound/soc/ti/omap-mcpdm.c | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

-- 
Peter

Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki.
Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki

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Comments

Tony Lindgren Oct. 25, 2019, 5:17 p.m. | #1
Hi,

* Peter Ujfalusi <peter.ujfalusi@ti.com> [191025 13:05]:
> McPDM module receives it's functional clock from external source. This

> clock is the pdmclk provided by the twl6040 audio IC. If the clock is not

> available all register accesses to McPDM fails and the module is not

> operational.

> 

> this has been lurking in my next-wip branch for some time...

> It might not needed anymore as I have not heard about issues with McPDM for a

> while.

> 

> It was dropped back then because some core parts were not picked in time and

> this caused some issues, but can not find the exact reason


Yes it's a strange solution to clock the internal mcpdm module
externally :)

AFAIK it's now already handled properly by ti-sysc. We have a common
omap4-mcpdm.dtsi configure mcpdm clock forthe module, then ti-sysc
driver defers probe until the mcpdm clock is available. And for omap5
we have omap5-board-common.dtsi configure it.

So probably the only thing omap-mcpdm.c driver needs to do is to
call PM runtime functions, maybe it's already doing that.

Regards,

Tony
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Peter Ujfalusi Oct. 25, 2019, 6:55 p.m. | #2
On 10/25/19 8:17 PM, Tony Lindgren wrote:
> Hi,

> 

> * Peter Ujfalusi <peter.ujfalusi@ti.com> [191025 13:05]:

>> McPDM module receives it's functional clock from external source. This

>> clock is the pdmclk provided by the twl6040 audio IC. If the clock is not

>> available all register accesses to McPDM fails and the module is not

>> operational.

>>

>> this has been lurking in my next-wip branch for some time...

>> It might not needed anymore as I have not heard about issues with McPDM for a

>> while.

>>

>> It was dropped back then because some core parts were not picked in time and

>> this caused some issues, but can not find the exact reason

> 

> Yes it's a strange solution to clock the internal mcpdm module

> externally :)


Strange is a bit of understatement ;)

> AFAIK it's now already handled properly by ti-sysc. We have a common

> omap4-mcpdm.dtsi configure mcpdm clock forthe module, then ti-sysc

> driver defers probe until the mcpdm clock is available. And for omap5

> we have omap5-board-common.dtsi configure it.


I see that the

clocks = <&twl6040>;
clock-names = "pdmclk";

are added to the mcpdm node (some patch from me, some new). But the
McPDM driver itself never requests this clock w/o this patch.

> So probably the only thing omap-mcpdm.c driver needs to do is to

> call PM runtime functions, maybe it's already doing that.


Yes, it has support for pm_runtime.

Looking at ti-sci I think I know why it works. ti-sci will get the
'pdmclk' as a clock for the device and going to manage it because the
SYSC_QUIRK_EXT_OPT_CLOCK is set for McPDM.
So pm_runtime is going to handle the clock coming from twl6040.

And now I remember to test these ti-sci changes :o
I wonder why I have not dropped this patch back then from my wip branch.

Let's just ignore this patch.

- Peter

Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki.
Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki
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Patch

diff --git a/sound/soc/ti/omap-mcpdm.c b/sound/soc/ti/omap-mcpdm.c
index b8c8290265c7..2c536947b69f 100644
--- a/sound/soc/ti/omap-mcpdm.c
+++ b/sound/soc/ti/omap-mcpdm.c
@@ -17,6 +17,7 @@ 
 #include <linux/err.h>
 #include <linux/io.h>
 #include <linux/irq.h>
+#include <linux/clk.h>
 #include <linux/slab.h>
 #include <linux/pm_runtime.h>
 #include <linux/of_device.h>
@@ -42,6 +43,7 @@  struct omap_mcpdm {
 	int irq;
 	struct pm_qos_request pm_qos_req;
 	int latency[2];
+	struct clk *pdmclk;
 
 	struct mutex mutex;
 
@@ -416,6 +418,10 @@  static int omap_mcpdm_probe(struct snd_soc_dai *dai)
 	struct omap_mcpdm *mcpdm = snd_soc_dai_get_drvdata(dai);
 	int ret;
 
+	ret = clk_prepare_enable(mcpdm->pdmclk);
+	if (ret)
+		return ret;
+
 	pm_runtime_enable(mcpdm->dev);
 
 	/* Disable lines while request is ongoing */
@@ -454,6 +460,7 @@  static int omap_mcpdm_remove(struct snd_soc_dai *dai)
 	if (pm_qos_request_active(&mcpdm->pm_qos_req))
 		pm_qos_remove_request(&mcpdm->pm_qos_req);
 
+	clk_disable_unprepare(mcpdm->pdmclk);
 	return 0;
 }
 
@@ -473,12 +480,19 @@  static int omap_mcpdm_suspend(struct snd_soc_dai *dai)
 		mcpdm->pm_active_count++;
 	}
 
+	clk_disable_unprepare(mcpdm->pdmclk);
+
 	return 0;
 }
 
 static int omap_mcpdm_resume(struct snd_soc_dai *dai)
 {
 	struct omap_mcpdm *mcpdm = snd_soc_dai_get_drvdata(dai);
+	int ret;
+
+	ret = clk_prepare_enable(mcpdm->pdmclk);
+	if (ret)
+		return ret;
 
 	if (mcpdm->pm_active_count) {
 		while (mcpdm->pm_active_count--)
@@ -573,6 +587,15 @@  static int asoc_mcpdm_probe(struct platform_device *pdev)
 
 	mcpdm->dev = &pdev->dev;
 
+	mcpdm->pdmclk = devm_clk_get(&pdev->dev, "pdmclk");
+	if (IS_ERR(mcpdm->pdmclk)) {
+		if (PTR_ERR(mcpdm->pdmclk) == -EPROBE_DEFER)
+			return -EPROBE_DEFER;
+		dev_warn(&pdev->dev, "Error getting pdmclk (%ld)!\n",
+			 PTR_ERR(mcpdm->pdmclk));
+		mcpdm->pdmclk = NULL;
+	}
+
 	ret =  devm_snd_soc_register_component(&pdev->dev,
 					       &omap_mcpdm_component,
 					       &omap_mcpdm_dai, 1);