linux-kernel - Re: [PATCH] w1: omap-hdq: Simplify driver with PM runtime autosuspend

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Message-ID: <20191215203319.2874ac04@aktux>
Date:   Sun, 15 Dec 2019 20:33:19 +0100
From:   Andreas Kemnade <andreas@...nade.info>
To:     Tony Lindgren <tony@...mide.com>
Cc:     Evgeniy Polyakov <zbr@...emap.net>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-kernel@...r.kernel.org, linux-omap@...r.kernel.org,
        Adam Ford <aford173@...il.com>,
        "Andrew F . Davis" <afd@...com>,
        "H . Nikolaus Schaller" <hns@...delico.com>,
        Vignesh R <vigneshr@...com>
Subject: Re: [PATCH] w1: omap-hdq: Simplify driver with PM runtime
 autosuspend

On Sun, 15 Dec 2019 09:38:17 -0800
Tony Lindgren <tony@...mide.com> wrote:

> We've had generic code handling module sysconfig and OCP reset registers
> for omap variants for many years now and all the drivers really needs to
> do is just call runtime PM functions.
> 
> Looks like the omap-hdq driver got only partially updated over the years
> to use runtime PM, and still has lots of custom PM code left.
> 
> We can replace all the custom code for sysconfig, OCP reset, and PM with
> just a few lines of runtime PM autosuspend code.
> 
> Note that the earlier driver specific usage count limit of four seems
> completely artificial and should not be an issue in normal use.
> 
> Cc: Adam Ford <aford173@...il.com>
> Cc: Andrew F. Davis <afd@...com>
> Cc: Andreas Kemnade <andreas@...nade.info>
> Cc: H. Nikolaus Schaller <hns@...delico.com>
> Cc: Vignesh R <vigneshr@...com>
> Signed-off-by: Tony Lindgren <tony@...mide.com>
> ---
> 
> 
> Can you guys please review and and test on gta04 and torpedo?
> 
I tried this after booting with init=/bin/bash and mounting kernel
filesystems (no off mode enabled):
root@(none):/# echo on >/sys/bus/platform/devices/480b2000.1w/power/control
root@(none):/# modprobe omap_hdq
[   49.590820] Driver for 1-wire Dallas network protocol.
[   49.598327] omap_hdq 480b2000.1w: OMAP HDQ Hardware Rev 0.5. Driver in Interrupt mode
root@(none):/# [   49.624572] w1_master_driver w1_bus_master1: Attaching one wire slave 01.000000000000 crc 3d
[   49.660980] power_supply bq27000-battery: power_supply_get_battery_info currently only supports devicetree

root@(none):/# time cat /sys/class/power_supply/bq27000-battery/voltage_now 
0

real    0m2.561s
user    0m0.008s
sys     0m0.002s
root@(none):/# time cat /sys/class/power_supply/bq27000-battery/voltage_now 
0

real    0m12.601s
user    0m0.010s
sys     0m0.002s
root@(none):/# time cat /sys/class/power_supply/bq27000-battery/voltage_now 
0

real    0m12.601s
user    0m0.010s
sys     0m0.002s
root@(none):/# 

No data could be read but some detection work seem to be done.
Of course, I also tried without that forced power on.

I hope I can find more time to analyze.
Looks like a nice cleanup but needs some work.

Regards,
Andreas