linux-kernel - Re: [PATCH v3] platform/chrome: Add cros_ec_readmem() helpers for I2C/SPI based ECs

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Message-ID: <20190121184017.GA5761@archbook>
Date:   Mon, 21 Jan 2019 10:40:17 -0800
From:   Moritz Fischer <mdf@...nel.org>
To:     Enric Balletbo Serra <eballetbo@...il.com>
Cc:     Moritz Fischer <mdf@...nel.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Enric Balletbo i Serra <enric.balletbo@...labora.com>,
        Benson Leung <bleung@...omium.org>,
        Guenter Roeck <groeck@...omium.org>,
        Lee Jones <lee.jones@...aro.org>, moritz@...us.com
Subject: Re: [PATCH v3] platform/chrome: Add cros_ec_readmem() helpers for
 I2C/SPI based ECs

Hi Enrico,

On Mon, Jan 21, 2019 at 06:32:48PM +0100, Enric Balletbo Serra wrote:
> Hi Moritz,
> 
> Missatge de Moritz Fischer <mdf@...nel.org> del dia dj., 10 de gen.
> 2019 a les 5:40:
> >
> > Add cros_ec_readmem() helpers for I2C/SPI based ECs.
> > Unlike the LPC based ECs the I2C/SPI based ones cannot just directly
> > read the mapped region, but have to resort to EC_CMD_READ_MEMMAP.
> >
> > This is useful for things like accessing fan speeds or temperatures.
> >
> > Signed-off-by: Moritz Fischer <mdf@...nel.org>
> > ---
> >
> > Hi all,
> >
> > This can be used for a hwmon or thermal driver such as [1], but also
> > alone can be used with 'ectool' via the ioctl() interface.
> >
> 
> ooi, did you try this with a Chromebook? Or only with your device?

Nope, mine has a dead battery (and no fans ... :-/) 
> 
> I was a bit worried on the side effects to expose this command to
> userspace, so I did a quick test, and to be honest I didn't like the
> result. Issuing the ioctl resulted on a reboot on the Chromebook I
> tested, which is not good. I didn't investigate more but I can say
> that this change, at least, will need some rework. I'll try to
> investigate a bit more on what is happening.

That sounds bad :-/

What chromebook did you run this on (so I can look at the EC code it is
running and figure out what's the difference). Maybe it has a different
configuration. It wasn't an x86 chromebook, right?

What was the ioctl you ran?

Thanks for testing,
Moritz