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Date:   Wed, 30 Sep 2020 10:54:42 +0200
From:   Andreas Kemnade <andreas@kemnade.info>
To:     rydberg@bitmath.org, jdelvare@suse.com, linux@roeck-us.net,
        linux-hwmon@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [REGRESSION] hwmon: (applesmc) avoid overlong udelay()
Message-ID: <20200930105442.3f642f6c@aktux>
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Hi,

after the $subject patch I get lots of errors like this:
[  120.378614] applesmc: send_byte(0x00, 0x0300) fail: 0x40
[  120.378621] applesmc: LKSB: write data fail
[  120.512782] applesmc: send_byte(0x00, 0x0300) fail: 0x40
[  120.512787] applesmc: LKSB: write data fail

CPU sticks at low speed and no fan is turning on.
Reverting this patch on top of 5.9-rc6 solves this problem.

Some information from dmidecode:

Base Board Information
        Manufacturer: Apple Inc.
        Product Name: Mac-7DF21CB3ED6977E5
        Version: MacBookAir6,2
=20
Handle 0x0020, DMI type 11, 5 bytes OEM Strings         String 1: Apple ROM=
 Version.  Model:       =E2=80=A6,=20
Handle 0x0020, DMI type 11, 5 bytes
OEM Strings
        String 1: Apple ROM Version.  Model:        MBA61.  EFI Version:  1=
22.0.0
        String 2: .0.0.  Built by:     root@saumon.  Date:         Wed Jun =
10 18:
        String 3: 10:36 PDT 2020.  Revision:     122 (B&I).  ROM Version:  =
F000_B
        String 4: 00.  Build Type:   Official Build, Release.  Compiler:   =
  Appl
        String 5: e clang version 3.0 (tags/Apple/clang-211.10.1) (based on=
 LLVM
        String 6: 3.0svn).
=20
Writing to things in /sys/devices/platform/applesmc.768 gives also the
said errors.
But writing 1 to fan1_maunal and 5000 to fan1_output turns the fan on
despite error messages.

Config used is: https://misc.andi.de1.cc/mac-config.gz

Regards,
Andreas