From: Andreas Kemnade <andreas@kemnade.info>
To: Brad Campbell <brad@fnarfbargle.com>
Cc: Guenter Roeck <linux@roeck-us.net>, Arnd Bergmann <arnd@arndb.de>,
rydberg@bitmath.org, Jean Delvare <jdelvare@suse.com>,
linux-hwmon@vger.kernel.org,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
hns@goldelico.com
Subject: Re: [REGRESSION] hwmon: (applesmc) avoid overlong udelay()
Date: Wed, 4 Nov 2020 14:20:57 +0100 [thread overview]
Message-ID: <20201104142057.62493c12@aktux> (raw)
In-Reply-To: <68467f1b-cea1-47ea-a4d4-8319214b072a@fnarfbargle.com>
On Tue, 3 Nov 2020 16:56:32 +1100
Brad Campbell <brad@fnarfbargle.com> wrote:
> On 3/11/20 10:56 am, Brad Campbell wrote:
>
> >
> > I've examined the code in VirtualSMC and I'm not convinced we were not waiting on the wrong bits.
> >
> > #define SMC_STATUS_AWAITING_DATA BIT0 ///< Ready to read data.
> > #define SMC_STATUS_IB_CLOSED BIT1 /// A write is pending.
> > #define SMC_STATUS_BUSY BIT2 ///< Busy processing a command.
> > #define SMC_STATUS_GOT_COMMAND BIT3 ///< The last input was a command.
> > #define SMC_STATUS_UKN_0x16 BIT4
> > #define SMC_STATUS_KEY_DONE BIT5
> > #define SMC_STATUS_READY BIT6 // Ready to work
> > #define SMC_STATUS_UKN_0x80 BIT7 // error
> >
> > Any chance you could try this patch? It's ugly, hacked together and currently fairly undocumented, but if it works I'll figure out how to clean it up (suggestions welcome).
> > It works on my MacbookPro 11,1.
>
> I had some time so I spent a bit of time refactoring and trying to clarify the magic numbers.
>
> I also did some fuzzing of the SMC and figured out where we can loosen the masks.
> This has some debug code in it to identify if any wait loops exceed 1 loop and if the SMC is reporting anything other than a clear "I'm waiting" prior to each command.
>
> You might see some of these :
> [ 51.316202] applesmc: wait_status looping 2: 0x44, 0x40, 0x4e
> [ 60.002547] applesmc: wait_status looping 2: 0x44, 0x40, 0x4e
> [ 60.130754] applesmc: wait_status looping 2: 0x44, 0x40, 0x4e
>
> I did some heavy tests and found that with the delays at the bottom of the loop about 50% of calls required no delay at all before a read or write and the other 50% require a single delay.
> I can count on one hand the number of times it's exceeded 1 loop, and the max thus far has been 5 loops.
>
That matches my experience. The only delay is at the end of the
command. Critcal seems to be that there is not too much delay in between.
[...]
> If anyone with a Mac having a conventional SMC and seeing issues on 5.9 could test this it'd be appreciated. I'm not saying this code is "correct", but it "works for me".
>
Seems to work here.
dmesg | grep applesmc
[ 1.350782] applesmc: key=561 fan=1 temp=33 index=33 acc=0 lux=2 kbd=1
[ 1.350922] applesmc applesmc.768: hwmon_device_register() is deprecated. Please convert the driver to use hwmon_device_register_with_info().
[ 17.748504] applesmc: wait_status looping 2: 0x4a, 0x4c, 0x4f
[ 212.008952] applesmc: wait_status looping 2: 0x44, 0x40, 0x4e
[ 213.033930] applesmc: wait_status looping 2: 0x44, 0x40, 0x4e
[ 213.167908] applesmc: wait_status looping 2: 0x44, 0x40, 0x4e
[ 219.087854] applesmc: wait_status looping 2: 0x44, 0x40, 0x4e
Tested it on top of 5.9
Regards,
Andreas
next prev parent reply other threads:[~2020-11-04 13:21 UTC|newest]
Thread overview: 58+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-30 8:54 [REGRESSION] hwmon: (applesmc) avoid overlong udelay() Andreas Kemnade
2020-09-30 16:44 ` Guenter Roeck
2020-09-30 20:00 ` Arnd Bergmann
2020-10-01 22:22 ` Andreas Kemnade
2020-10-02 4:07 ` Guenter Roeck
2020-10-06 7:02 ` Andreas Kemnade
2020-11-02 23:56 ` Brad Campbell
2020-11-03 5:56 ` Brad Campbell
2020-11-04 13:20 ` Andreas Kemnade [this message]
2020-11-05 2:18 ` Brad Campbell
2020-11-05 4:22 ` Brad Campbell
2020-11-05 4:43 ` Guenter Roeck
2020-11-05 5:05 ` Brad Campbell
2020-11-05 5:26 ` Guenter Roeck
2020-11-05 5:47 ` [PATCH] applesmc: Re-work SMC comms v1 Brad Campbell
2020-11-05 7:26 ` [PATCH] applesmc: Re-work SMC comms v2 Brad Campbell
2020-11-05 7:56 ` Henrik Rydberg
2020-11-05 8:15 ` Andreas Kemnade
2020-11-05 8:30 ` Brad Campbell
2020-11-05 10:31 ` Henrik Rydberg
2020-11-06 16:26 ` Henrik Rydberg
2020-11-06 20:02 ` Henrik Rydberg
2020-11-07 18:31 ` Henrik Rydberg
2020-11-08 0:09 ` Brad Campbell
2020-11-08 8:22 ` Henrik Rydberg
2020-11-08 1:00 ` [PATCH v3] applesmc: Re-work SMC comms Brad Campbell
2020-11-08 8:35 ` Henrik Rydberg
2020-11-08 10:14 ` Henrik Rydberg
2020-11-08 11:57 ` Brad Campbell
2020-11-08 12:04 ` Henrik Rydberg
2020-11-09 13:06 ` Brad Campbell
2020-11-09 17:08 ` Henrik Rydberg
2020-11-09 22:52 ` Brad Campbell
2020-11-08 16:06 ` Guenter Roeck
2020-11-09 0:25 ` Brad Campbell
2020-11-10 2:04 ` Brad Campbell
2020-11-10 4:55 ` Guenter Roeck
2020-11-10 5:40 ` Brad Campbell
2020-11-10 16:02 ` Guenter Roeck
2020-11-09 8:44 ` Andreas Kemnade
2020-11-09 9:51 ` Brad Campbell
2020-11-11 3:37 ` [PATCH v4 0/1] " Brad Campbell
2020-11-11 4:55 ` [PATCH v1] applesmc: Cleanups on top of re-work comms Brad Campbell
2020-11-11 3:38 ` [PATCH v4 1/1] applesmc: Re-work SMC comms Brad Campbell
2020-11-11 5:56 ` Guenter Roeck
2020-11-11 7:05 ` Brad Campbell
2020-11-11 13:06 ` [PATCH v5 " Brad Campbell
2020-11-11 20:05 ` Henrik Rydberg
2020-11-11 23:28 ` Brad Campbell
2020-11-12 3:08 ` [PATCH v6 " Brad Campbell
2020-11-12 17:20 ` Guenter Roeck
2020-11-06 23:11 ` [PATCH] applesmc: Re-work SMC comms v2 Brad Campbell
2020-11-05 8:12 ` Andreas Kemnade
2020-11-05 16:12 ` Guenter Roeck
2020-11-06 0:02 ` Brad Campbell
2020-11-06 3:08 ` Guenter Roeck
2020-11-09 9:27 ` [PATCH] applesmc: Re-work SMC comms v1 kernel test robot
2020-11-05 9:48 ` [REGRESSION] hwmon: (applesmc) avoid overlong udelay() Arnd Bergmann
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