linux-kernel - Re: [PATCH] spi: Force the registration of the spidev devices

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CAMuHMdWJ730G_a6=vQgs4gV837am5KKd7zEhU2FaHw2cpv=aRA@mail.gmail.com>
Date:	Wed, 13 May 2015 21:10:48 +0200
From:	Geert Uytterhoeven <geert@...ux-m68k.org>
To:	Maxime Ripard <maxime.ripard@...e-electrons.com>
Cc:	Mark Brown <broonie@...nel.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Hans de Goede <hdegoede@...hat.com>,
	linux-spi <linux-spi@...r.kernel.org>,
	Martin Sperl <kernel@...tin.sperl.org>,
	Michal Suchanek <hramrach@...il.com>
Subject: Re: [PATCH] spi: Force the registration of the spidev devices

On Wed, May 13, 2015 at 2:51 PM, Maxime Ripard
<maxime.ripard@...e-electrons.com> wrote:
>> > This also adds an i2cdev-like feeling, where you get all the
>> > spidev devices all the time, without any modification.
>>
>> I2C is a bit safer here since it's a shared bus so you can't do
>> anything to devices not connected to the bus by mistake.
>
> I'm not sure to understand what you mean here. How is SPI different
> from that aspect?

If you talk to a nonexistent i2c device, nothing happens, as it just sends
a message with a nonexistent address on the shared bus.

If you talk to a nonexistent spi device, hell may break loose if e.g. some
"smart" hardware engineer used the "unused" CS as a pull-up for the
_RESET line on an external device... It's a bit like banging random
"unused" GPIOs.

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/