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[23.128.96.18]) by mx.google.com with ESMTP id gn11si11196615ejc.638.2020.11.03.08.09.23; Tue, 03 Nov 2020 08:09:47 -0800 (PST) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; dkim=pass header.i=@kernel.org header.s=default header.b=jeufbIs6; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=linuxfoundation.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726820AbgKCQHv (ORCPT + 99 others); Tue, 3 Nov 2020 11:07:51 -0500 Received: from mail.kernel.org ([198.145.29.99]:45220 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725993AbgKCQHv (ORCPT ); Tue, 3 Nov 2020 11:07:51 -0500 Received: from localhost (83-86-74-64.cable.dynamic.v4.ziggo.nl [83.86.74.64]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 852B920773; Tue, 3 Nov 2020 16:07:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1604419670; bh=0C3Om95v4rkiVPQy1gKQdTuxFaRCNJMzTxnpPVwYvNA=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=jeufbIs6Do9Xlt93/4Oy0lYISit5zvCR+D6O2O2yK5AfuMY09BvsVQARycPHlN6IE +l1s6BOvazyFgnAO3ki4rD7/43g+IuFxowO9eJH7uBQl009UZ55jTDoTXclib9iTnM aP2bIB4eTZtxm/MGS9HFML5+O8+r31Fbo8vRrmRI= Date: Tue, 3 Nov 2020 17:08:42 +0100 From: Greg Kroah-Hartman To: Daniel Gutson Cc: Derek Kiernan , Tudor Ambarus , Miquel Raynal , Richard Weinberger , Vignesh Raghavendra , Mika Westerberg , Arnd Bergmann , Mauro Carvalho Chehab , linux-kernel , Richard Hughes , Alex Bazhaniuk , linux-mtd Subject: Re: [PATCH] mtd: spi-nor: intel-spi: Split intel-spi reading from writing Message-ID: <20201103160842.GA4153227@kroah.com> References: <20201028214359.384918-1-daniel.gutson@eclypsium.com> <20201029054110.GA3039992@kroah.com> <20201029191505.GC986195@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Nov 03, 2020 at 12:18:01PM -0300, Daniel Gutson wrote: > On Thu, Oct 29, 2020 at 4:14 PM Greg Kroah-Hartman > wrote: > > > > On Thu, Oct 29, 2020 at 12:39:08PM -0300, Daniel Gutson wrote: > > > On Thu, Oct 29, 2020 at 2:40 AM Greg Kroah-Hartman > > > wrote: > > > > > > > > On Wed, Oct 28, 2020 at 06:43:59PM -0300, Daniel Gutson wrote: > > > > > This patch separates the writing part of the intel-spi drivers > > > > > so the 'dangerous' part can be set/unset independently. > > > > > This way, the kernel can be configured to include the reading > > > > > parts of the driver which can be used without > > > > > the dangerous write operations that can turn the system > > > > > unbootable. > > > > > > > > > > Signed-off-by: Daniel Gutson > > > > > --- > > > > > drivers/mtd/spi-nor/controllers/Kconfig | 39 ++++++++++++--------- > > > > > drivers/mtd/spi-nor/controllers/intel-spi.c | 12 +++++-- > > > > > 2 files changed, 33 insertions(+), 18 deletions(-) > > > > > > > > > > diff --git a/drivers/mtd/spi-nor/controllers/Kconfig b/drivers/mtd/spi-nor/controllers/Kconfig > > > > > index 5c0e0ec2e6d1..491c755fea49 100644 > > > > > --- a/drivers/mtd/spi-nor/controllers/Kconfig > > > > > +++ b/drivers/mtd/spi-nor/controllers/Kconfig > > > > > @@ -31,34 +31,41 @@ config SPI_INTEL_SPI > > > > > tristate > > > > > > > > > > config SPI_INTEL_SPI_PCI > > > > > - tristate "Intel PCH/PCU SPI flash PCI driver (DANGEROUS)" > > > > > + tristate "Intel PCH/PCU SPI flash PCI driver" > > > > > depends on X86 && PCI > > > > > select SPI_INTEL_SPI > > > > > help > > > > > - This enables PCI support for the Intel PCH/PCU SPI controller in > > > > > - master mode. This controller is present in modern Intel hardware > > > > > - and is used to hold BIOS and other persistent settings. Using > > > > > - this driver it is possible to upgrade BIOS directly from Linux. > > > > > - > > > > > - Say N here unless you know what you are doing. Overwriting the > > > > > - SPI flash may render the system unbootable. > > > > > + This enables read only PCI support for the Intel PCH/PCU SPI > > > > > + controller in master mode. This controller is present in modern > > > > > + Intel hardware and is used to hold BIOS and other persistent settings. > > > > > + Using this driver it is possible to read the SPI chip directly > > > > > + from Linux. > > > > > > > > > > To compile this driver as a module, choose M here: the module > > > > > will be called intel-spi-pci. > > > > > > > > > > config SPI_INTEL_SPI_PLATFORM > > > > > - tristate "Intel PCH/PCU SPI flash platform driver (DANGEROUS)" > > > > > + tristate "Intel PCH/PCU SPI flash platform driver" > > > > > depends on X86 > > > > > select SPI_INTEL_SPI > > > > > help > > > > > - This enables platform support for the Intel PCH/PCU SPI > > > > > + This enables read only platform support for the Intel PCH/PCU SPI > > > > > controller in master mode. This controller is present in modern > > > > > - Intel hardware and is used to hold BIOS and other persistent > > > > > - settings. Using this driver it is possible to upgrade BIOS > > > > > - directly from Linux. > > > > > + Intel hardware and is used to hold BIOS and other persistent settings. > > > > > + Using this driver it is possible to read the SPI chip directly > > > > > + from Linux. > > > > > + > > > > > + To compile this driver as a module, choose M here: the module > > > > > + will be called intel-spi-pci. > > > > > + > > > > > +config SPI_INTEL_SPI_WRITE > > > > > + bool "Intel PCH/PCU SPI flash drivers write operations (DANGEROUS)" > > > > > + depends on SPI_INTEL_SPI_PCI || SPI_INTEL_SPI_PLATFORM > > > > > + help > > > > > + This enables full read/write support for the Intel PCH/PCU SPI > > > > > + controller. > > > > > + Using this option it may be possible to upgrade BIOS directly > > > > > + from Linux. > > > > > > > > > > Say N here unless you know what you are doing. Overwriting the > > > > > SPI flash may render the system unbootable. > > > > > - > > > > > - To compile this driver as a module, choose M here: the module > > > > > - will be called intel-spi-platform. > > > > > diff --git a/drivers/mtd/spi-nor/controllers/intel-spi.c b/drivers/mtd/spi-nor/controllers/intel-spi.c > > > > > index b54a56a68100..8d8053395c3d 100644 > > > > > --- a/drivers/mtd/spi-nor/controllers/intel-spi.c > > > > > +++ b/drivers/mtd/spi-nor/controllers/intel-spi.c > > > > > @@ -266,6 +266,7 @@ static int intel_spi_read_block(struct intel_spi *ispi, void *buf, size_t size) > > > > > return 0; > > > > > } > > > > > > > > > > +#ifdef CONFIG_SPI_INTEL_SPI_WRITE > > > > > > > > > > > > > > > > Please do not add #ifdef to .c files, that's not the proper kernel > > > > coding style at all, and just makes maintaining this file much much > > > > harder over time. > > > > > > > > Split things out into two different files if you really need to do this. > > > > > > What about the static functions that I'll need to turn non-static and > > > in a header file? > > > I mean, the functions that the functions in the new file will have to call. > > > Should I do that, turn static functions into non-static and declared > > > in a header file? > > > > No idea, but again, no #ifdefs in .c files like this, that is not the > > proper kernel coding style as it is not maintainable for the lifespan > > that we have to maintain code. > > Is it acceptable to leave static functions unused and let the optimizer > remove them as DCE? You will get build warnings if you do that, right? You have thousands of examples of how to do this correct, it shouldn't be that tough :) thanks, greg k-h