[alsa-devel] [PATCH v3 1/4] ASoC: es8316: judge PCM rate at later timing
This patch change the judge timing about playing/capturing PCM rate.
Original code set constraints list of PCM rate limits at set_sysclk. This strategy works well if system is using fixed rate clock.
But some boards and SoC (such as RockPro64 and RockChip I2S) has connected SoC MCLK out to ES8316 MCLK in. In this case, SoC side I2S will choose suitable frequency of MCLK such as fs * mclk-fs when user starts playing or capturing.
Bad scenario as follows (mclk-fs = 256): - Initialize sysclk by correct value (Ex. 12.288MHz) - ES8316 set constraints of PCM rate by sysclk 48kHz (1/256), 32kHz (1/384), 30.720kHz (1/400), 24kHz (1/512), 16kHz (1/768), 12kHz (1/1024) - Play 48kHz sound, it's acceptable - Sysclk is not changed
- Play 32kHz sound, it's acceptable - Set sysclk by 8.192MHz (= fs * mclk-fs = 32k * 256) - ES8316 set constraints of PCM rate by sysclk 32kHz (1/256), 21.33kHz (1/384), 20.48kHz (1/400), 16kHz (1/512), 10.66kHz (1/768), 8kHz (1/1024)
- Play 48kHz again, but it's NOT acceptable because constraints list does not allow 48kHz
Root cause of this strange behavior is changing constraints list at set_sysclk timing. It seems that is too early to determine. So this patch does not use constraints list and check PCM rate limit more later timing at hw_params.
Signed-off-by: Katsuhiro Suzuki katsuhiro@katsuster.net --- sound/soc/codecs/es8316.c | 37 +++++++++++++++---------------------- 1 file changed, 15 insertions(+), 22 deletions(-)
diff --git a/sound/soc/codecs/es8316.c b/sound/soc/codecs/es8316.c index ed2959dbe1fb..229808fa627c 100644 --- a/sound/soc/codecs/es8316.c +++ b/sound/soc/codecs/es8316.c @@ -363,27 +363,12 @@ static int es8316_set_dai_sysclk(struct snd_soc_dai *codec_dai, { struct snd_soc_component *component = codec_dai->component; struct es8316_priv *es8316 = snd_soc_component_get_drvdata(component); - int i; - int count = 0;
es8316->sysclk = freq;
if (freq == 0) return 0;
- /* Limit supported sample rates to ones that can be autodetected - * by the codec running in slave mode. - */ - for (i = 0; i < NR_SUPPORTED_MCLK_LRCK_RATIOS; i++) { - const unsigned int ratio = supported_mclk_lrck_ratios[i]; - - if (freq % ratio == 0) - es8316->allowed_rates[count++] = freq / ratio; - } - - es8316->sysclk_constraints.list = es8316->allowed_rates; - es8316->sysclk_constraints.count = count; - return 0; }
@@ -449,13 +434,6 @@ static int es8316_pcm_startup(struct snd_pcm_substream *substream, return -EINVAL; }
- /* The set of sample rates that can be supported depends on the - * MCLK supplied to the CODEC. - */ - snd_pcm_hw_constraint_list(substream->runtime, 0, - SNDRV_PCM_HW_PARAM_RATE, - &es8316->sysclk_constraints); - return 0; }
@@ -466,12 +444,27 @@ static int es8316_pcm_hw_params(struct snd_pcm_substream *substream, struct snd_soc_component *component = dai->component; struct es8316_priv *es8316 = snd_soc_component_get_drvdata(component); u8 wordlen = 0; + int i;
if (!es8316->sysclk) { dev_err(component->dev, "No MCLK configured\n"); return -EINVAL; }
+ /* Limit supported sample rates to ones that can be autodetected + * by the codec running in slave mode. + */ + for (i = 0; i < NR_SUPPORTED_MCLK_LRCK_RATIOS; i++) { + const unsigned int ratio = supported_mclk_lrck_ratios[i]; + + if (es8316->sysclk % ratio != 0) + continue; + if (es8316->sysclk / ratio == params_rate(params)) + break; + } + if (i == NR_SUPPORTED_MCLK_LRCK_RATIOS) + return -EINVAL; + switch (params_format(params)) { case SNDRV_PCM_FORMAT_S16_LE: wordlen = ES8316_SERDATA2_LEN_16;
This patch introduce clock property for MCLK master freq control. Driver will set rate of MCLK master if set_sysclk is called and changing sysclk by board driver.
Signed-off-by: Katsuhiro Suzuki katsuhiro@katsuster.net
---
Changes from v1: - Output logs if clock error is found - Disable and unprepare mclk when remove this driver --- sound/soc/codecs/es8316.c | 35 +++++++++++++++++++++++++++++++++++ 1 file changed, 35 insertions(+)
diff --git a/sound/soc/codecs/es8316.c b/sound/soc/codecs/es8316.c index 229808fa627c..ab41f2c056bd 100644 --- a/sound/soc/codecs/es8316.c +++ b/sound/soc/codecs/es8316.c @@ -9,6 +9,7 @@
#include <linux/module.h> #include <linux/acpi.h> +#include <linux/clk.h> #include <linux/delay.h> #include <linux/i2c.h> #include <linux/mod_devicetable.h> @@ -33,6 +34,7 @@ static const unsigned int supported_mclk_lrck_ratios[] = {
struct es8316_priv { struct mutex lock; + struct clk *mclk; struct regmap *regmap; struct snd_soc_component *component; struct snd_soc_jack *jack; @@ -363,12 +365,19 @@ static int es8316_set_dai_sysclk(struct snd_soc_dai *codec_dai, { struct snd_soc_component *component = codec_dai->component; struct es8316_priv *es8316 = snd_soc_component_get_drvdata(component); + int ret;
es8316->sysclk = freq;
if (freq == 0) return 0;
+ if (es8316->mclk) { + ret = clk_set_rate(es8316->mclk, freq); + if (ret) + return ret; + } + return 0; }
@@ -693,9 +702,26 @@ static int es8316_set_jack(struct snd_soc_component *component, static int es8316_probe(struct snd_soc_component *component) { struct es8316_priv *es8316 = snd_soc_component_get_drvdata(component); + int ret;
es8316->component = component;
+ es8316->mclk = devm_clk_get(component->dev, "mclk"); + if (PTR_ERR(es8316->mclk) == -EPROBE_DEFER) + return -EPROBE_DEFER; + if (IS_ERR(es8316->mclk)) { + dev_err(component->dev, "clock is invalid, ignored\n"); + es8316->mclk = NULL; + } + + if (es8316->mclk) { + ret = clk_prepare_enable(es8316->mclk); + if (ret) { + dev_err(component->dev, "unable to enable clock\n"); + return ret; + } + } + /* Reset codec and enable current state machine */ snd_soc_component_write(component, ES8316_RESET, 0x3f); usleep_range(5000, 5500); @@ -718,8 +744,17 @@ static int es8316_probe(struct snd_soc_component *component) return 0; }
+static void es8316_remove(struct snd_soc_component *component) +{ + struct es8316_priv *es8316 = snd_soc_component_get_drvdata(component); + + if (es8316->mclk) + clk_disable_unprepare(es8316->mclk); +} + static const struct snd_soc_component_driver soc_component_dev_es8316 = { .probe = es8316_probe, + .remove = es8316_remove, .set_jack = es8316_set_jack, .controls = es8316_snd_controls, .num_controls = ARRAY_SIZE(es8316_snd_controls),
The patch
ASoC: es8316: add clock control of MCLK
has been applied to the asoc tree at
https://git.kernel.org/pub/scm/linux/kernel/git/broonie/sound.git for-5.4
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 6dd567dc964878c04269a44114ef13693712edf1 Mon Sep 17 00:00:00 2001
From: Katsuhiro Suzuki katsuhiro@katsuster.net Date: Wed, 4 Sep 2019 01:53:20 +0900 Subject: [PATCH] ASoC: es8316: add clock control of MCLK
This patch introduce clock property for MCLK master freq control. Driver will set rate of MCLK master if set_sysclk is called and changing sysclk by board driver.
[Modified slightly to apply without an earlier patch in the series due to context diffs -- broonie]
Signed-off-by: Katsuhiro Suzuki katsuhiro@katsuster.net Link: https://lore.kernel.org/r/20190903165322.20791-2-katsuhiro@katsuster.net Signed-off-by: Mark Brown broonie@kernel.org --- sound/soc/codecs/es8316.c | 36 +++++++++++++++++++++++++++++++++++- 1 file changed, 35 insertions(+), 1 deletion(-)
diff --git a/sound/soc/codecs/es8316.c b/sound/soc/codecs/es8316.c index 6db002cc2058..6248b01ca049 100644 --- a/sound/soc/codecs/es8316.c +++ b/sound/soc/codecs/es8316.c @@ -9,6 +9,7 @@
#include <linux/module.h> #include <linux/acpi.h> +#include <linux/clk.h> #include <linux/delay.h> #include <linux/i2c.h> #include <linux/mod_devicetable.h> @@ -33,6 +34,7 @@ static const unsigned int supported_mclk_lrck_ratios[] = {
struct es8316_priv { struct mutex lock; + struct clk *mclk; struct regmap *regmap; struct snd_soc_component *component; struct snd_soc_jack *jack; @@ -360,7 +362,7 @@ static int es8316_set_dai_sysclk(struct snd_soc_dai *codec_dai, { struct snd_soc_component *component = codec_dai->component; struct es8316_priv *es8316 = snd_soc_component_get_drvdata(component); - int i; + int i, ret; int count = 0;
es8316->sysclk = freq; @@ -368,6 +370,12 @@ static int es8316_set_dai_sysclk(struct snd_soc_dai *codec_dai, if (freq == 0) return 0;
+ if (es8316->mclk) { + ret = clk_set_rate(es8316->mclk, freq); + if (ret) + return ret; + } + /* Limit supported sample rates to ones that can be autodetected * by the codec running in slave mode. */ @@ -697,9 +705,26 @@ static int es8316_set_jack(struct snd_soc_component *component, static int es8316_probe(struct snd_soc_component *component) { struct es8316_priv *es8316 = snd_soc_component_get_drvdata(component); + int ret;
es8316->component = component;
+ es8316->mclk = devm_clk_get(component->dev, "mclk"); + if (PTR_ERR(es8316->mclk) == -EPROBE_DEFER) + return -EPROBE_DEFER; + if (IS_ERR(es8316->mclk)) { + dev_err(component->dev, "clock is invalid, ignored\n"); + es8316->mclk = NULL; + } + + if (es8316->mclk) { + ret = clk_prepare_enable(es8316->mclk); + if (ret) { + dev_err(component->dev, "unable to enable clock\n"); + return ret; + } + } + /* Reset codec and enable current state machine */ snd_soc_component_write(component, ES8316_RESET, 0x3f); usleep_range(5000, 5500); @@ -722,8 +747,17 @@ static int es8316_probe(struct snd_soc_component *component) return 0; }
+static void es8316_remove(struct snd_soc_component *component) +{ + struct es8316_priv *es8316 = snd_soc_component_get_drvdata(component); + + if (es8316->mclk) + clk_disable_unprepare(es8316->mclk); +} + static const struct snd_soc_component_driver soc_component_dev_es8316 = { .probe = es8316_probe, + .remove = es8316_remove, .set_jack = es8316_set_jack, .controls = es8316_snd_controls, .num_controls = ARRAY_SIZE(es8316_snd_controls),
On Tue, Sep 3, 2019 at 7:54 PM Katsuhiro Suzuki katsuhiro@katsuster.net wrote:
This patch introduce clock property for MCLK master freq control. Driver will set rate of MCLK master if set_sysclk is called and changing sysclk by board driver.
Signed-off-by: Katsuhiro Suzuki katsuhiro@katsuster.net
if (es8316->mclk) {
You don't need this if clock has been requested as optional (clk_get_optional() or so).
ret = clk_set_rate(es8316->mclk, freq);if (ret)return ret;}
es8316->mclk = devm_clk_get(component->dev, "mclk");if (PTR_ERR(es8316->mclk) == -EPROBE_DEFER)return -EPROBE_DEFER;if (IS_ERR(es8316->mclk)) {dev_err(component->dev, "clock is invalid, ignored\n");es8316->mclk = NULL;}
devm_clk_get_optional()
if (es8316->mclk) {
Ditto as above.
ret = clk_prepare_enable(es8316->mclk);if (ret) {dev_err(component->dev, "unable to enable clock\n");return ret;}}
if (es8316->mclk)
Ditto.
clk_disable_unprepare(es8316->mclk);+}
Hello Andy,
Thank you for reviewing.
On 2019/09/04 23:37, Andy Shevchenko wrote:
On Tue, Sep 3, 2019 at 7:54 PM Katsuhiro Suzuki katsuhiro@katsuster.net wrote:
This patch introduce clock property for MCLK master freq control. Driver will set rate of MCLK master if set_sysclk is called and changing sysclk by board driver.
Signed-off-by: Katsuhiro Suzuki katsuhiro@katsuster.net
if (es8316->mclk) {You don't need this if clock has been requested as optional (clk_get_optional() or so).
ret = clk_set_rate(es8316->mclk, freq);if (ret)return ret;}
es8316->mclk = devm_clk_get(component->dev, "mclk");if (PTR_ERR(es8316->mclk) == -EPROBE_DEFER)return -EPROBE_DEFER;if (IS_ERR(es8316->mclk)) {dev_err(component->dev, "clock is invalid, ignored\n");es8316->mclk = NULL;}devm_clk_get_optional()
if (es8316->mclk) {Ditto as above.
ret = clk_prepare_enable(es8316->mclk);if (ret) {dev_err(component->dev, "unable to enable clock\n");return ret;}}
if (es8316->mclk)Ditto.
clk_disable_unprepare(es8316->mclk);+}
Indeed, NULL check of MCLK is not needed. I'll make and send fixup patch.
Best Regards, Katsuhiro Suzuki
This patch supports some type of machine drivers that use fixed clock rate. After applied this patch, sysclk == 0 means there is no constraint of sound rate and other values will set constraints which is derived by sysclk setting.
Signed-off-by: Katsuhiro Suzuki katsuhiro@katsuster.net
---
Changes from v2: - Newly added --- sound/soc/codecs/es8316.c | 24 ++++-------------------- 1 file changed, 4 insertions(+), 20 deletions(-)
diff --git a/sound/soc/codecs/es8316.c b/sound/soc/codecs/es8316.c index ab41f2c056bd..bf390bc64177 100644 --- a/sound/soc/codecs/es8316.c +++ b/sound/soc/codecs/es8316.c @@ -432,20 +432,6 @@ static int es8316_set_dai_fmt(struct snd_soc_dai *codec_dai, return 0; }
-static int es8316_pcm_startup(struct snd_pcm_substream *substream, - struct snd_soc_dai *dai) -{ - struct snd_soc_component *component = dai->component; - struct es8316_priv *es8316 = snd_soc_component_get_drvdata(component); - - if (es8316->sysclk == 0) { - dev_err(component->dev, "No sysclk provided\n"); - return -EINVAL; - } - - return 0; -} - static int es8316_pcm_hw_params(struct snd_pcm_substream *substream, struct snd_pcm_hw_params *params, struct snd_soc_dai *dai) @@ -455,17 +441,16 @@ static int es8316_pcm_hw_params(struct snd_pcm_substream *substream, u8 wordlen = 0; int i;
- if (!es8316->sysclk) { - dev_err(component->dev, "No MCLK configured\n"); - return -EINVAL; - } - /* Limit supported sample rates to ones that can be autodetected * by the codec running in slave mode. */ for (i = 0; i < NR_SUPPORTED_MCLK_LRCK_RATIOS; i++) { const unsigned int ratio = supported_mclk_lrck_ratios[i];
+ /* Accept any rates if sysclk is 0. */ + if (es8316->sysclk == 0) + break; + if (es8316->sysclk % ratio != 0) continue; if (es8316->sysclk / ratio == params_rate(params)) @@ -509,7 +494,6 @@ static int es8316_mute(struct snd_soc_dai *dai, int mute) SNDRV_PCM_FMTBIT_S24_LE)
static const struct snd_soc_dai_ops es8316_ops = { - .startup = es8316_pcm_startup, .hw_params = es8316_pcm_hw_params, .set_fmt = es8316_set_dai_fmt, .set_sysclk = es8316_set_dai_sysclk,
On Wed, Sep 04, 2019 at 01:53:21AM +0900, Katsuhiro Suzuki wrote:
This patch supports some type of machine drivers that use fixed clock rate. After applied this patch, sysclk == 0 means there is no constraint of sound rate and other values will set constraints which is derived by sysclk setting.
This is to support variable clock rate isn't it?
This patch adds missing DT-bindings document for Everest ES8316.
Signed-off-by: Katsuhiro Suzuki katsuhiro@katsuster.net --- .../bindings/sound/everest,es8316.txt | 20 +++++++++++++++++++ 1 file changed, 20 insertions(+) create mode 100644 Documentation/devicetree/bindings/sound/everest,es8316.txt
diff --git a/Documentation/devicetree/bindings/sound/everest,es8316.txt b/Documentation/devicetree/bindings/sound/everest,es8316.txt new file mode 100644 index 000000000000..aefcff9c48a2 --- /dev/null +++ b/Documentation/devicetree/bindings/sound/everest,es8316.txt @@ -0,0 +1,20 @@ +Everest ES8316 audio CODEC + +This device supports both I2C and SPI. + +Required properties: + + - compatible : should be "everest,es8316" + - reg : the I2C address of the device for I2C + - clocks : a list of phandle, should contain entries for clock-names + - clock-names : should include as follows: + "mclk" : master clock (MCLK) of the device + +Example: + +es8316: codec@11 { + compatible = "everest,es8316"; + reg = <0x11>; + clocks = <&clks 10>; + clock-names = "mclk"; +};
The patch
ASoC: es8316: add DT-bindings
has been applied to the asoc tree at
https://git.kernel.org/pub/scm/linux/kernel/git/broonie/sound.git for-5.4
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 3a3edd6ffe671115c4b3d715f08ed0cf4e927ce1 Mon Sep 17 00:00:00 2001
From: Katsuhiro Suzuki katsuhiro@katsuster.net Date: Wed, 4 Sep 2019 01:53:22 +0900 Subject: [PATCH] ASoC: es8316: add DT-bindings
This patch adds missing DT-bindings document for Everest ES8316.
Signed-off-by: Katsuhiro Suzuki katsuhiro@katsuster.net Link: https://lore.kernel.org/r/20190903165322.20791-4-katsuhiro@katsuster.net Signed-off-by: Mark Brown broonie@kernel.org --- .../bindings/sound/everest,es8316.txt | 20 +++++++++++++++++++ 1 file changed, 20 insertions(+) create mode 100644 Documentation/devicetree/bindings/sound/everest,es8316.txt
diff --git a/Documentation/devicetree/bindings/sound/everest,es8316.txt b/Documentation/devicetree/bindings/sound/everest,es8316.txt new file mode 100644 index 000000000000..aefcff9c48a2 --- /dev/null +++ b/Documentation/devicetree/bindings/sound/everest,es8316.txt @@ -0,0 +1,20 @@ +Everest ES8316 audio CODEC + +This device supports both I2C and SPI. + +Required properties: + + - compatible : should be "everest,es8316" + - reg : the I2C address of the device for I2C + - clocks : a list of phandle, should contain entries for clock-names + - clock-names : should include as follows: + "mclk" : master clock (MCLK) of the device + +Example: + +es8316: codec@11 { + compatible = "everest,es8316"; + reg = <0x11>; + clocks = <&clks 10>; + clock-names = "mclk"; +};
On Wed, Sep 04, 2019 at 01:53:19AM +0900, Katsuhiro Suzuki wrote:
Root cause of this strange behavior is changing constraints list at set_sysclk timing. It seems that is too early to determine. So this patch does not use constraints list and check PCM rate limit more later timing at hw_params.
hw_params is a bit late to impose constraints, you want them to be available to be available to the application before it gets as far as picking the parameters it wants so that you don't get hw_params failing due to an invalid configuration. That makes everything run more smoothly, applications should be able to trust the constraints they got and some will not handle failures well.
The way this works with the variable MCLKs is that you end up in one of two cases (wm8731 and wm8741 do this):
1. The system is idle, MCLK is set to 0. In this case no constraints are set and we just set MCLK to whatever is required in hw_params() in the machine driver. 2. One direction is active, MCLK is set to whatever that needed. In this case startup() sets constraints derived from the MCLK.
There are races in this if streams are being started and torn down simultaneously, there's not much we can do about them with the API the way it is so we do have to validate in hw_params() anyway but it should be validation not constraint imposition.
If the system has a fixed MCLK it just sets that on probe then we always get the constraints applied on startup through the same code that handles case 2.
Hello Mark,
On 2019/09/04 2:48, Mark Brown wrote:
On Wed, Sep 04, 2019 at 01:53:19AM +0900, Katsuhiro Suzuki wrote:
Root cause of this strange behavior is changing constraints list at set_sysclk timing. It seems that is too early to determine. So this patch does not use constraints list and check PCM rate limit more later timing at hw_params.
hw_params is a bit late to impose constraints, you want them to be available to be available to the application before it gets as far as picking the parameters it wants so that you don't get hw_params failing due to an invalid configuration. That makes everything run more smoothly, applications should be able to trust the constraints they got and some will not handle failures well.
The way this works with the variable MCLKs is that you end up in one of two cases (wm8731 and wm8741 do this):
1. The system is idle, MCLK is set to 0. In this case no constraints are set and we just set MCLK to whatever is required in hw_params() in the machine driver. 2. One direction is active, MCLK is set to whatever that needed. In this case startup() sets constraints derived from the MCLK.There are races in this if streams are being started and torn down simultaneously, there's not much we can do about them with the API the way it is so we do have to validate in hw_params() anyway but it should be validation not constraint imposition.
If the system has a fixed MCLK it just sets that on probe then we always get the constraints applied on startup through the same code that handles case 2.
Thank you for explanation. I agree with apply no constraints if MCLK is set to 0, and suitable constraints if MCLK is set to other values like as wm8731 and wm8741 drivers.
I'll change my patch set and send.
Would you tell me one more thing. I don't understand who sets MCLK to 0. Is it needed original machine driver instead of audio-graph-card?
On my test environment (audio-graph-card + Rockchip I2S + ES8316), it seems audio-graph-card has never called set_sysclk() with freq = 0 after stop play/capture sound. So my env will go to bad scenario as I described in this patch.
Best Regards, Katsuhiro Suzuki
On Thu, Sep 05, 2019 at 12:06:23AM +0900, Katsuhiro Suzuki wrote:
Would you tell me one more thing. I don't understand who sets MCLK to 0. Is it needed original machine driver instead of audio-graph-card?
On my test environment (audio-graph-card + Rockchip I2S + ES8316), it seems audio-graph-card has never called set_sysclk() with freq = 0 after stop play/capture sound. So my env will go to bad scenario as I described in this patch.
You shouldn't need a custom machine driver - you'll just be the first person who ran into this with audio-graph-card. I'd just add this support to the audio-graph-card, either with custom startup and shutdown callbacks or using a set_bias_level() callback (both get used, I'd guess the set_bias_level() is easier since you don't need to reference count anything).
On 2019/09/05 0:30, Mark Brown wrote:
On Thu, Sep 05, 2019 at 12:06:23AM +0900, Katsuhiro Suzuki wrote:
Would you tell me one more thing. I don't understand who sets MCLK to 0. Is it needed original machine driver instead of audio-graph-card?
On my test environment (audio-graph-card + Rockchip I2S + ES8316), it seems audio-graph-card has never called set_sysclk() with freq = 0 after stop play/capture sound. So my env will go to bad scenario as I described in this patch.
You shouldn't need a custom machine driver - you'll just be the first person who ran into this with audio-graph-card. I'd just add this support to the audio-graph-card, either with custom startup and shutdown callbacks or using a set_bias_level() callback (both get used, I'd guess the set_bias_level() is easier since you don't need to reference count anything).
Oh, I understand current situation. I'll try it. Thanks for your support!
Best Regards, Katsuhiro Suzuki
participants (3)
-
Andy Shevchenko -
Katsuhiro Suzuki -
Mark Brown