Re: [PATCH] Input: pwm-beeper: support customized freq for SND_BELL

From: Heiko Schocher
Date: Tue Feb 14 2017 - 00:02:40 EST

Hello Dmitry,

Am 14.02.2017 um 05:27 schrieb Dmitry Torokhov:
On Wed, Feb 08, 2017 at 10:11:21AM +0000, Jonas Mark (ST-FIR/ENG1) wrote:
Hello Dmitry,

extend the pwm-beeper driver to support customized frequency
for SND_BELL from device tree.

No, SND_BELL is literally SND_TONE @1000Hz. There should be no
customizing. If applications want to use different frequency then should
be using SND_TONE.

We are not aiming for an application shortcut here. Instead, changing
the bell frequency shall be a system setting. That is, every
application which wants to make a bell sound shall use the alternative

The reason why we are deviating from the default 1000 Hz is that on
our hardware we are using a loudspeaker which is rated for 2.7 kHz.
That is, it will only sound at the specified volume and frequency if
you feed it with a 2.7 kHz square wave. If you deviate from it, e.g.
by using 1000 Hz, the output will be dim and squeaky. Worst case,
SND_BELL would be completely silent on our system. So the only bell
sound we can reliably generate on our system has 2.7 kHz.

OK, fair enough. Please address Rob's comments on binding and resend.

Done already, just waited for more comments before sending v2.

Also I am not sure why you needed to change the switch statement around,
you only need to replace 1000 with value from the attribute.

Hmm.. the resulting code looks cleaner to me ... First we check all
the reasons for returning an error code, after that, we can do
the functions work ... but I can revert this part ... should I ?

Oh, and please use device_property_*() API instead of of_*().

Thanks! Good tip, changed.

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