linux-kernel - Re: [PATCH 1/1] regmap: debugfs: runtime resume a device when reading registers

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Message-ID: <7625183.EvYhyI6sBW@steina-w>
Date: Wed, 10 Jan 2024 13:46:31 +0100
From: Alexander Stein <alexander.stein@...tq-group.com>
To: Mark Brown <broonie@...nel.org>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>, "Rafael J . Wysocki" <rafael@...nel.org>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/1] regmap: debugfs: runtime resume a device when reading registers

Am Mittwoch, 10. Januar 2024, 13:23:17 CET schrieb Mark Brown:
> On Wed, Jan 10, 2024 at 10:53:58AM +0100, Alexander Stein wrote:
> > If the registers shall be read from device, runtime resume it in order
> > to enable a possiblly attached power domain before accessing the device.
> 
> The idea is that the debugfs interface isn't supposed to be disruptive
> to the thing being debugged.  It would be better to detect if there will
> be problems and report the status as busy.

In my case the device is actually unused, runtime suspended, thus disabled 
power domain. That's totally different to busy. In this case dumping the 
registers is non-disruptive, unless you account enabling/disabling the power 
domain as well. Any attached clock is already enabled/disabled, but power 
domains are not.

Best regards,
Alexander
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