Date:   Tue, 7 Feb 2023 16:45:22 +0200
From:   Mika Westerberg <mika.westerberg@linux.intel.com>
To:     Michael Walle <michael@walle.cc>
Cc:     mauro.lima@eclypsium.com, broonie@kernel.org,
        linux-kernel@vger.kernel.org, linux-spi@vger.kernel.org
Subject: Re: [PATCH 1/1] spi: intel: Remove DANGEROUS tag from pci driver
Message-ID: <Y+JkArdW747OtMO9@black.fi.intel.com>
References: <20230206183143.75274-2-mauro.lima@eclypsium.com>
 <20230207135254.2465816-1-michael@walle.cc>
 <Y+JaKF4FZQKqeGs7@black.fi.intel.com>
 <8797addc6c063b867b94cce352191aab@walle.cc>
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Disposition: inline
In-Reply-To: <8797addc6c063b867b94cce352191aab@walle.cc>
Precedence: bulk

Hi,

On Tue, Feb 07, 2023 at 03:11:26PM +0100, Michael Walle wrote:
> Hi Mika,
> 
> Am 2023-02-07 15:03, schrieb Mika Westerberg:
> > On Tue, Feb 07, 2023 at 02:52:54PM +0100, Michael Walle wrote:
> > > > Modern CPUs exposes this controller as PCI device that only uses
> > > > hardware sequencing capabilities which is safer than software
> > > > sequencing.
> > > > Leave the platform driver as *DANGEROUS* and update help text since
> > > > most of these controllers are using software sequencing.
> > > 
> > > Out of curiosity, what is hardware sequencing? Maybe this should
> > > be explained a bit more in the Kconfig help text. Looks like the
> > > dangerous was there because you can update the bios and that
> > > could eventually lead to a bricked mainboard. So hardware
> > > sequencing helps there? how?
> > 
> > Hardware sequencing means the controller exposes just a bunch of "high
> > level" operations to the software.
> 
> Ok, I figured it would have been something to do with the SPI driver
> just supporting these high level ops. But even with that background
> it was hard to connect that to the "hardware sequencing". The help
> text should be somewhat understandable to the user/distro people/whoever,
> right? So I'd suggest to explain that a bit more in detail, or don't
> use the term hardware sequencing at all. I'm not sure.

I agree it should be made more understandable for the distro folks. At
least add some explanation why it is OK to select this.

Mauro, can you do that in the next version?

> > Such as read, write, erase and so on
> > but does not allow running the actual "low level" SPI-NOR opcodes.
> > Software sequencing on the other hand allows running pretty much any
> > opcode and this is what caused problems for certain Lenovo laptops few
> > years back that then resulted adding DANGEROUS to the Kconfig.
> 
> That information should go into the commit message.

+1