linux-kernel - Re: [RFC PATCH] Input: omap4-keypad: react on keypresses if device is runtime-suspended

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Date:   Wed, 11 Oct 2023 13:07:26 +0300
From:   Tony Lindgren <tony@...mide.com>
To:     Andreas Kemnade <andreas@...nade.info>
Cc:     dmitry.torokhov@...il.com, Jonathan.Cameron@...wei.com,
        robh@...nel.org, frank.li@...o.com, linux-input@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-omap@...r.kernel.org
Subject: Re: [RFC PATCH] Input: omap4-keypad: react on keypresses if device
 is runtime-suspended

Hi,

* Andreas Kemnade <andreas@...nade.info> [230929 23:01]:
> According to SWPU235AB, table 26-6, fclk is required to generate events
> at least on OMAP4460, so keep fclk enabled all the time the device
> is opened.

Sorry for the delay, the patch looks good to me:

Reviewed-by: Tony Lindgren <tony@...mide.com>

> Open questions:
> - Should we rather (or also use) padconf irqs?

The keypad is in the wakeup domain and has SYSC_OMAP2_ENAWAKEUP set in
the dts, so padconf irqs should not be needed as long as the device is
clocked. As the source clock is sys_32k_ck, not sure if gating it would
save any power, so padconf interrupts are probably not needed.

> - It seems not to be required everywhere. Does it harm somewhere?

Sounds like on 4430 the gate bit does not do anything while on 4460 it
does. The source clock seems to be sys_32k_ck so it's enabled anyways
and should not affect power management.

Regards,

Tony