Messages in this thread | | | From | Arnd Bergmann <> | Subject | Re: [PATCH] leds-lm3530: replace pwm platform functions with generic pwm functions | Date | Mon, 20 Aug 2012 05:37:48 +0000 |
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On Monday 20 August 2012, Kim, Milo wrote: > +#ifdef CONFIG_PWM > +static int lm3530_pwm_request(struct lm3530_data *drvdata) > +{ > + int pwm_id; > + > + /* if the pwm device exists, skip requesting the device */ > + if (drvdata->pwm) > + return 0; > + > + pwm_id = drvdata->pdata ? drvdata->pdata->pwm_id : 0; > + > + drvdata->pwm = pwm_request(pwm_id, "lm3530-pwm"); > + drvdata->period_ns = drvdata->pdata ? drvdata->pdata->period_ns : 0; > + > + return IS_ERR(drvdata->pwm) ? PTR_ERR(drvdata->pwm) : 0; > +} > +
A few comments on this:
* Rather than having to do the #ifdef here, I think it would be better if the PWM subsystem provided stub functions for pwm_request, pwm_config, pwm_enable, pwm_disable and pwm_free that do nothing, so you can in effect let the compiler optimize away the above code.
* I don't understand why you need the "if (rvdata->pwm) return 0;" case. It's normally better to do the initialization exactly once from the probe() function. You might want to return -EPROBE_DEFER if the pwm source is not yet available though.
Arnd
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