[PATCH v6] staging: greybus: introduce pwm_ops::apply

[PATCH v6] staging: greybus: introduce pwm_ops::apply

[Song Chen]

Introduce newer .apply function in pwm_ops to replace legacy operations
including enable, disable, config and set_polarity.

This guarantees atomic changes of the pwm controller configuration.

Signed-off-by: Song Chen <chensong_2000@189.cn>

---
v2:
1, define duty_cycle and period as u64 in gb_pwm_config_operation.
2, define duty and period as u64 in gb_pwm_config_request.
3, disable before configuring duty and period if the eventual goal
   is a disabled state.

v3:
Regarding duty_cycle and period, I read more discussion in this thread,
min, warn or -EINVAL, seems no perfect way acceptable for everyone.
How about we limit their value to INT_MAX and throw a warning at the
same time when they are wrong?

v4:
1, explain why legacy operations are replaced.
2, cap the value of period and duty to U32_MAX.

v5:
1, revise commit message.

v6:
1, revise commit message.
2, explain why capping the value of period and duty to U32_MAX in
   comment.
---
 drivers/staging/greybus/pwm.c | 64 ++++++++++++++++++++++-------------
 1 file changed, 40 insertions(+), 24 deletions(-)

diff --git a/drivers/staging/greybus/pwm.c b/drivers/staging/greybus/pwm.c
index 891a6a672378..ad20ec24031e 100644
--- a/drivers/staging/greybus/pwm.c
+++ b/drivers/staging/greybus/pwm.c
@@ -204,43 +204,59 @@ static void gb_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
 	gb_pwm_deactivate_operation(pwmc, pwm->hwpwm);
 }
 
-static int gb_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
-			 int duty_ns, int period_ns)
+static int gb_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
+			const struct pwm_state *state)
 {
+	int err;
+	bool enabled = pwm->state.enabled;
+	u64 period = state->period;
+	u64 duty_cycle = state->duty_cycle;
 	struct gb_pwm_chip *pwmc = pwm_chip_to_gb_pwm_chip(chip);
 
-	return gb_pwm_config_operation(pwmc, pwm->hwpwm, duty_ns, period_ns);
-};
+	/* Set polarity */
+	if (state->polarity != pwm->state.polarity) {
+		if (enabled) {
+			gb_pwm_disable_operation(pwmc, pwm->hwpwm);
+			enabled = false;
+		}
+		err = gb_pwm_set_polarity_operation(pwmc, pwm->hwpwm, state->polarity);
+		if (err)
+			return err;
+	}
 
-static int gb_pwm_set_polarity(struct pwm_chip *chip, struct pwm_device *pwm,
-			       enum pwm_polarity polarity)
-{
-	struct gb_pwm_chip *pwmc = pwm_chip_to_gb_pwm_chip(chip);
+	if (!state->enabled) {
+		if (enabled)
+			gb_pwm_disable_operation(pwmc, pwm->hwpwm);
+		return 0;
+	}
 
-	return gb_pwm_set_polarity_operation(pwmc, pwm->hwpwm, polarity);
-};
+	/*
+	 * Set period and duty cycle
+	 *
+	 * PWM privodes 64-bit period and duty_cycle, but greybus only accepts
+	 * 32-bit, so their values have to be limited to U32_MAX.
+	 */
+	if (period > U32_MAX)
+		period = U32_MAX;
 
-static int gb_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
-{
-	struct gb_pwm_chip *pwmc = pwm_chip_to_gb_pwm_chip(chip);
+	if (duty_cycle > period)
+		duty_cycle = period;
 
-	return gb_pwm_enable_operation(pwmc, pwm->hwpwm);
-};
+	err = gb_pwm_config_operation(pwmc, pwm->hwpwm, duty_cycle, period);
+	if (err)
+		return err;
 
-static void gb_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
-{
-	struct gb_pwm_chip *pwmc = pwm_chip_to_gb_pwm_chip(chip);
+	/* enable/disable */
+	if (!enabled)
+		return gb_pwm_enable_operation(pwmc, pwm->hwpwm);
 
-	gb_pwm_disable_operation(pwmc, pwm->hwpwm);
-};
+	return 0;
+}
 
 static const struct pwm_ops gb_pwm_ops = {
 	.request = gb_pwm_request,
 	.free = gb_pwm_free,
-	.config = gb_pwm_config,
-	.set_polarity = gb_pwm_set_polarity,
-	.enable = gb_pwm_enable,
-	.disable = gb_pwm_disable,
+	.apply = gb_pwm_apply,
 	.owner = THIS_MODULE,
 };
 
-- 
2.25.1

Re: [PATCH v6] staging: greybus: introduce pwm_ops::apply

[Alex Elder]

On 3/18/22 4:57 AM, Song Chen wrote:
> Introduce newer .apply function in pwm_ops to replace legacy operations
> including enable, disable, config and set_polarity.
> 
> This guarantees atomic changes of the pwm controller configuration.
> 
> Signed-off-by: Song Chen <chensong_2000@189.cn>

I had another comment suggestion but you've been through enough.
Thanks for working this to completion.

Reviewed-by: Alex Elder <elder@linaro.org>

> 
> ---
> v2:
> 1, define duty_cycle and period as u64 in gb_pwm_config_operation.
> 2, define duty and period as u64 in gb_pwm_config_request.
> 3, disable before configuring duty and period if the eventual goal
>     is a disabled state.
> 
> v3:
> Regarding duty_cycle and period, I read more discussion in this thread,
> min, warn or -EINVAL, seems no perfect way acceptable for everyone.
> How about we limit their value to INT_MAX and throw a warning at the
> same time when they are wrong?
> 
> v4:
> 1, explain why legacy operations are replaced.
> 2, cap the value of period and duty to U32_MAX.
> 
> v5:
> 1, revise commit message.
> 
> v6:
> 1, revise commit message.
> 2, explain why capping the value of period and duty to U32_MAX in
>     comment.
> ---
>   drivers/staging/greybus/pwm.c | 64 ++++++++++++++++++++++-------------
>   1 file changed, 40 insertions(+), 24 deletions(-)
> 
> diff --git a/drivers/staging/greybus/pwm.c b/drivers/staging/greybus/pwm.c
> index 891a6a672378..ad20ec24031e 100644
> --- a/drivers/staging/greybus/pwm.c
> +++ b/drivers/staging/greybus/pwm.c
> @@ -204,43 +204,59 @@ static void gb_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
>   	gb_pwm_deactivate_operation(pwmc, pwm->hwpwm);
>   }
>   
> -static int gb_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
> -			 int duty_ns, int period_ns)
> +static int gb_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
> +			const struct pwm_state *state)
>   {
> +	int err;
> +	bool enabled = pwm->state.enabled;
> +	u64 period = state->period;
> +	u64 duty_cycle = state->duty_cycle;
>   	struct gb_pwm_chip *pwmc = pwm_chip_to_gb_pwm_chip(chip);
>   
> -	return gb_pwm_config_operation(pwmc, pwm->hwpwm, duty_ns, period_ns);
> -};
> +	/* Set polarity */
> +	if (state->polarity != pwm->state.polarity) {
> +		if (enabled) {
> +			gb_pwm_disable_operation(pwmc, pwm->hwpwm);
> +			enabled = false;
> +		}
> +		err = gb_pwm_set_polarity_operation(pwmc, pwm->hwpwm, state->polarity);
> +		if (err)
> +			return err;
> +	}
>   
> -static int gb_pwm_set_polarity(struct pwm_chip *chip, struct pwm_device *pwm,
> -			       enum pwm_polarity polarity)
> -{
> -	struct gb_pwm_chip *pwmc = pwm_chip_to_gb_pwm_chip(chip);
> +	if (!state->enabled) {
> +		if (enabled)
> +			gb_pwm_disable_operation(pwmc, pwm->hwpwm);
> +		return 0;
> +	}
>   
> -	return gb_pwm_set_polarity_operation(pwmc, pwm->hwpwm, polarity);
> -};
> +	/*
> +	 * Set period and duty cycle
> +	 *
> +	 * PWM privodes 64-bit period and duty_cycle, but greybus only accepts
> +	 * 32-bit, so their values have to be limited to U32_MAX.
> +	 */
> +	if (period > U32_MAX)
> +		period = U32_MAX;
>   
> -static int gb_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
> -{
> -	struct gb_pwm_chip *pwmc = pwm_chip_to_gb_pwm_chip(chip);
> +	if (duty_cycle > period)
> +		duty_cycle = period;
>   
> -	return gb_pwm_enable_operation(pwmc, pwm->hwpwm);
> -};
> +	err = gb_pwm_config_operation(pwmc, pwm->hwpwm, duty_cycle, period);
> +	if (err)
> +		return err;
>   
> -static void gb_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
> -{
> -	struct gb_pwm_chip *pwmc = pwm_chip_to_gb_pwm_chip(chip);
> +	/* enable/disable */
> +	if (!enabled)
> +		return gb_pwm_enable_operation(pwmc, pwm->hwpwm);
>   
> -	gb_pwm_disable_operation(pwmc, pwm->hwpwm);
> -};
> +	return 0;
> +}
>   
>   static const struct pwm_ops gb_pwm_ops = {
>   	.request = gb_pwm_request,
>   	.free = gb_pwm_free,
> -	.config = gb_pwm_config,
> -	.set_polarity = gb_pwm_set_polarity,
> -	.enable = gb_pwm_enable,
> -	.disable = gb_pwm_disable,
> +	.apply = gb_pwm_apply,
>   	.owner = THIS_MODULE,
>   };
>   

Re: [PATCH v6] staging: greybus: introduce pwm_ops::apply

[chensong]

hi Alex,

On 2022/3/18 下午8:15, Alex Elder wrote:
> On 3/18/22 4:57 AM, Song Chen wrote:
>> Introduce newer .apply function in pwm_ops to replace legacy operations
>> including enable, disable, config and set_polarity.
>>
>> This guarantees atomic changes of the pwm controller configuration.
>>
>> Signed-off-by: Song Chen <chensong_2000@189.cn>
> 
> I had another comment suggestion but you've been through enough.
> Thanks for working this to completion.

sorry about that, i probably missed it somehow. Thanks for the 
understanding.

Song

> 
> Reviewed-by: Alex Elder <elder@linaro.org>
> 
>>
>> ---
>> v2:
>> 1, define duty_cycle and period as u64 in gb_pwm_config_operation.
>> 2, define duty and period as u64 in gb_pwm_config_request.
>> 3, disable before configuring duty and period if the eventual goal
>>     is a disabled state.
>>
>> v3:
>> Regarding duty_cycle and period, I read more discussion in this thread,
>> min, warn or -EINVAL, seems no perfect way acceptable for everyone.
>> How about we limit their value to INT_MAX and throw a warning at the
>> same time when they are wrong?
>>
>> v4:
>> 1, explain why legacy operations are replaced.
>> 2, cap the value of period and duty to U32_MAX.
>>
>> v5:
>> 1, revise commit message.
>>
>> v6:
>> 1, revise commit message.
>> 2, explain why capping the value of period and duty to U32_MAX in
>>     comment.
>> ---
>>   drivers/staging/greybus/pwm.c | 64 ++++++++++++++++++++++-------------
>>   1 file changed, 40 insertions(+), 24 deletions(-)
>>
>> diff --git a/drivers/staging/greybus/pwm.c 
>> b/drivers/staging/greybus/pwm.c
>> index 891a6a672378..ad20ec24031e 100644
>> --- a/drivers/staging/greybus/pwm.c
>> +++ b/drivers/staging/greybus/pwm.c
>> @@ -204,43 +204,59 @@ static void gb_pwm_free(struct pwm_chip *chip, 
>> struct pwm_device *pwm)
>>       gb_pwm_deactivate_operation(pwmc, pwm->hwpwm);
>>   }
>> -static int gb_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
>> -             int duty_ns, int period_ns)
>> +static int gb_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
>> +            const struct pwm_state *state)
>>   {
>> +    int err;
>> +    bool enabled = pwm->state.enabled;
>> +    u64 period = state->period;
>> +    u64 duty_cycle = state->duty_cycle;
>>       struct gb_pwm_chip *pwmc = pwm_chip_to_gb_pwm_chip(chip);
>> -    return gb_pwm_config_operation(pwmc, pwm->hwpwm, duty_ns, 
>> period_ns);
>> -};
>> +    /* Set polarity */
>> +    if (state->polarity != pwm->state.polarity) {
>> +        if (enabled) {
>> +            gb_pwm_disable_operation(pwmc, pwm->hwpwm);
>> +            enabled = false;
>> +        }
>> +        err = gb_pwm_set_polarity_operation(pwmc, pwm->hwpwm, 
>> state->polarity);
>> +        if (err)
>> +            return err;
>> +    }
>> -static int gb_pwm_set_polarity(struct pwm_chip *chip, struct 
>> pwm_device *pwm,
>> -                   enum pwm_polarity polarity)
>> -{
>> -    struct gb_pwm_chip *pwmc = pwm_chip_to_gb_pwm_chip(chip);
>> +    if (!state->enabled) {
>> +        if (enabled)
>> +            gb_pwm_disable_operation(pwmc, pwm->hwpwm);
>> +        return 0;
>> +    }
>> -    return gb_pwm_set_polarity_operation(pwmc, pwm->hwpwm, polarity);
>> -};
>> +    /*
>> +     * Set period and duty cycle
>> +     *
>> +     * PWM privodes 64-bit period and duty_cycle, but greybus only 
>> accepts
>> +     * 32-bit, so their values have to be limited to U32_MAX.
>> +     */
>> +    if (period > U32_MAX)
>> +        period = U32_MAX;
>> -static int gb_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
>> -{
>> -    struct gb_pwm_chip *pwmc = pwm_chip_to_gb_pwm_chip(chip);
>> +    if (duty_cycle > period)
>> +        duty_cycle = period;
>> -    return gb_pwm_enable_operation(pwmc, pwm->hwpwm);
>> -};
>> +    err = gb_pwm_config_operation(pwmc, pwm->hwpwm, duty_cycle, period);
>> +    if (err)
>> +        return err;
>> -static void gb_pwm_disable(struct pwm_chip *chip, struct pwm_device 
>> *pwm)
>> -{
>> -    struct gb_pwm_chip *pwmc = pwm_chip_to_gb_pwm_chip(chip);
>> +    /* enable/disable */
>> +    if (!enabled)
>> +        return gb_pwm_enable_operation(pwmc, pwm->hwpwm);
>> -    gb_pwm_disable_operation(pwmc, pwm->hwpwm);
>> -};
>> +    return 0;
>> +}
>>   static const struct pwm_ops gb_pwm_ops = {
>>       .request = gb_pwm_request,
>>       .free = gb_pwm_free,
>> -    .config = gb_pwm_config,
>> -    .set_polarity = gb_pwm_set_polarity,
>> -    .enable = gb_pwm_enable,
>> -    .disable = gb_pwm_disable,
>> +    .apply = gb_pwm_apply,
>>       .owner = THIS_MODULE,
>>   };
> 
> 

Re: [PATCH v6] staging: greybus: introduce pwm_ops::apply

[Uwe Kleine-König]

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Hello,

On Fri, Mar 18, 2022 at 05:57:12PM +0800, Song Chen wrote:
> Introduce newer .apply function in pwm_ops to replace legacy operations
> including enable, disable, config and set_polarity.
> 
> This guarantees atomic changes of the pwm controller configuration.
> 
> Signed-off-by: Song Chen <chensong_2000@189.cn>

for the record: This patch was applied by Greg, I'm marking it as
"handled elsewhere" in the pwm patchwork.

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | https://www.pengutronix.de/ |

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