From: Arnd Bergmann <arnd@arndb.de>
To: Daniel Gutson <daniel@eclypsium.com>
Cc: Tudor Ambarus <tudor.ambarus@microchip.com>,
Miquel Raynal <miquel.raynal@bootlin.com>,
Richard Weinberger <richard@nod.at>,
Vignesh Raghavendra <vigneshr@ti.com>,
Mika Westerberg <mika.westerberg@linux.intel.com>,
Boris Brezillon <bbrezillon@kernel.org>,
linux-mtd <linux-mtd@lists.infradead.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Alex Bazhaniuk <alex@eclypsium.com>,
Richard Hughes <hughsient@gmail.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Subject: Re: [PATCH] mtd: spi-nor: intel-spi: Do not try to make the SPI flash chip writable
Date: Thu, 13 Aug 2020 17:41:07 +0200 [thread overview]
Message-ID: <CAK8P3a13N_wNORz_3cYHTN8t29pPrY+dJ+g+1Ga_MmG1TmrUQw@mail.gmail.com> (raw)
In-Reply-To: <CAFmMkTFzmC=aY0gR6urLu-8Oq8aeHBUWi-TodG8XhXKCcC057A@mail.gmail.com>
On Tue, Aug 4, 2020 at 11:26 PM Daniel Gutson <daniel@eclypsium.com> wrote:
> On Tue, Aug 4, 2020 at 5:46 PM Arnd Bergmann <arnd@arndb.de> wrote:
> > > But wait, Mika, the author of the file, asked earlier not to remove
> > > the module parameter of intel-spi, and just remove the unconditional
> > > attempt to turn the chip writable in intle-spi-pci.
> >
> > Yes, and I think that is fine (aside from the inconsistency with bay trail
> > that you have not commented on),
>
> There are two inconsistencies before any of my patches:
> 1) in intel-spi.c: uses the module parameter only for bay trail.
> 2) intel-spi.c uses a module parameter whereas intel-spi-pci doesn't
Neither of these matches what I see in the source code. Please
check again.
Once more: intel-spi.c has a module parameter that controls writing
to the device regardless of the back-end (platform or pci), purely
in software. The hardware write-protect setting where available
works in addition that and prevents writing even if the module
parameter is set to writeable.
> > but that only touches the hardware
> > write-protection, which doesn't really have any effect unless user
> > space also configures the driver module to allow writing to the
> > mtd device.
> >
> > > So I'm not touching intel-pci, just removing that code from
> > > intel-spi-pci without adding a new module parameter.
> > >
> > > Are you aligned on this?
> >
> > One of us is still very confused about what the driver does.
> > You seem to have gone back to saying that without the
> > change a user could just write to the device even without
> > passing the module parameter to intel-spi.ko?
>
> What I'm trying to say is that, if the BIOS is unlocked
> (no driver involvement here), the intel-spi-pci turns the
> chip writable even without changing the module parameter of intel-spi.
> This is because the attempt to turn the chip writable occurs in
> the probing of intel-spi-pci, that is, earlier than the intel-spi
> initialization.
My question was why you even care whether the hardware
bit is set to writeable if the driver disallows writing. I think the
answer is that you misread the driver.
Arnd
next prev parent reply other threads:[~2020-08-13 15:41 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-04 13:58 [PATCH] mtd: spi-nor: intel-spi: Do not try to make the SPI flash chip writable Daniel Gutson
2020-08-04 14:08 ` Mika Westerberg
2020-08-04 15:21 ` Arnd Bergmann
[not found] ` <CAFmMkTHEm8k+5GZkVJbDZMEhMwpsqVKRb-hGskSpBstdLRuFyA@mail.gmail.com>
2020-08-04 19:06 ` Arnd Bergmann
2020-08-04 19:57 ` Daniel Gutson
2020-08-04 20:46 ` Arnd Bergmann
2020-08-04 21:26 ` Daniel Gutson
2020-08-12 15:41 ` Daniel Gutson
2020-08-13 9:01 ` Greg Kroah-Hartman
[not found] ` <CAFmMkTFgjW+9gNfx=2SU7B0foww=SLiiyVi+P-hZpEFDbMTf2Q@mail.gmail.com>
2020-08-13 11:47 ` Greg Kroah-Hartman
2020-08-13 15:41 ` Arnd Bergmann [this message]
2020-08-13 21:40 ` Daniel Gutson
2020-08-16 8:41 ` Arnd Bergmann
2020-08-18 15:55 ` Daniel Gutson
2020-08-19 6:57 ` Mika Westerberg
2020-08-19 8:38 ` Arnd Bergmann
2020-08-19 9:11 ` Mika Westerberg
2020-08-22 16:06 ` Arnd Bergmann
2020-08-24 8:22 ` Mika Westerberg
2020-08-24 9:08 ` Arnd Bergmann
2020-08-24 9:15 ` Mika Westerberg
2020-08-24 9:31 ` Arnd Bergmann
2020-08-24 9:44 ` Mika Westerberg
2020-08-24 16:00 ` Daniel Gutson
2020-08-19 9:19 ` David Laight
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