From: Andy Shevchenko <andriy.shevchenko@linux.intel.com> To: Robin Murphy <robin.murphy@arm.com> Cc: bcm-kernel-feedback-list <bcm-kernel-feedback-list@broadcom.com>, linux-rpi-kernel <linux-rpi-kernel@lists.infradead.org>, "linux-arm Mailing List" <linux-arm-kernel@lists.infradead.org>, linux-pci <linux-pci@vger.kernel.org>, "Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>, "Jim Quinlan" <jim2101024@gmail.com>, "Nicolas Saenz Julienne" <nsaenz@kernel.org>, "Florian Fainelli" <f.fainelli@gmail.com>, "Lorenzo Pieralisi" <lorenzo.pieralisi@arm.com>, "Rob Herring" <robh@kernel.org>, "Krzysztof Wilczyński" <kw@linux.com>, "Bjorn Helgaas" <bhelgaas@google.com> Subject: Re: [PATCH v2 1/1] PCI: brcmstb: Use BIT() as __GENMASK() is for internal use only Date: Mon, 15 Nov 2021 16:39:23 +0200 [thread overview] Message-ID: <YZJxG7JFAfIqr1/f@smile.fi.intel.com> (raw) In-Reply-To: <CAHp75VeJ8ZiD=qQVfeahUjGZduFRJJ5683hn8f4810JYEzsCyw@mail.gmail.com> On Mon, Nov 15, 2021 at 04:14:21PM +0200, Andy Shevchenko wrote: > On Mon, Nov 15, 2021 at 4:01 PM Robin Murphy <robin.murphy@arm.com> wrote: > > On 2021-11-15 11:20, Andy Shevchenko wrote: > > > Use BIT() as __GENMASK() is for internal use only. The rationale > > > of switching to BIT() is to provide better generated code. The > > > GENMASK() against non-constant numbers may produce an ugly assembler > > > code. On contrary the BIT() is simply converted to corresponding shift > > > operation. > > > > FWIW, If you care about code quality and want the compiler to do the > > obvious thing, why not specify it as the obvious thing: > > > > u32 val = ~0 << msi->legacy_shift; > > Obvious and buggy (from the C standard point of view)? :-) Forgot to mention that BIT() is also makes it easy to avoid such mistake. > > Personally I don't think that abusing BIT() in the context of setting > > multiple bits is any better than abusing __GENMASK()... > > No, BIT() is not abused here, but __GENMASK(). > > After all it's up to you, folks, consider that as a bug report. -- With Best Regards, Andy Shevchenko
WARNING: multiple messages have this Message-ID (diff)
From: Andy Shevchenko <andriy.shevchenko@linux.intel.com> To: Robin Murphy <robin.murphy@arm.com> Cc: bcm-kernel-feedback-list <bcm-kernel-feedback-list@broadcom.com>, linux-rpi-kernel <linux-rpi-kernel@lists.infradead.org>, "linux-arm Mailing List" <linux-arm-kernel@lists.infradead.org>, linux-pci <linux-pci@vger.kernel.org>, "Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>, "Jim Quinlan" <jim2101024@gmail.com>, "Nicolas Saenz Julienne" <nsaenz@kernel.org>, "Florian Fainelli" <f.fainelli@gmail.com>, "Lorenzo Pieralisi" <lorenzo.pieralisi@arm.com>, "Rob Herring" <robh@kernel.org>, "Krzysztof Wilczyński" <kw@linux.com>, "Bjorn Helgaas" <bhelgaas@google.com> Subject: Re: [PATCH v2 1/1] PCI: brcmstb: Use BIT() as __GENMASK() is for internal use only Date: Mon, 15 Nov 2021 16:39:23 +0200 [thread overview] Message-ID: <YZJxG7JFAfIqr1/f@smile.fi.intel.com> (raw) In-Reply-To: <CAHp75VeJ8ZiD=qQVfeahUjGZduFRJJ5683hn8f4810JYEzsCyw@mail.gmail.com> On Mon, Nov 15, 2021 at 04:14:21PM +0200, Andy Shevchenko wrote: > On Mon, Nov 15, 2021 at 4:01 PM Robin Murphy <robin.murphy@arm.com> wrote: > > On 2021-11-15 11:20, Andy Shevchenko wrote: > > > Use BIT() as __GENMASK() is for internal use only. The rationale > > > of switching to BIT() is to provide better generated code. The > > > GENMASK() against non-constant numbers may produce an ugly assembler > > > code. On contrary the BIT() is simply converted to corresponding shift > > > operation. > > > > FWIW, If you care about code quality and want the compiler to do the > > obvious thing, why not specify it as the obvious thing: > > > > u32 val = ~0 << msi->legacy_shift; > > Obvious and buggy (from the C standard point of view)? :-) Forgot to mention that BIT() is also makes it easy to avoid such mistake. > > Personally I don't think that abusing BIT() in the context of setting > > multiple bits is any better than abusing __GENMASK()... > > No, BIT() is not abused here, but __GENMASK(). > > After all it's up to you, folks, consider that as a bug report. -- With Best Regards, Andy Shevchenko _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2021-11-15 14:40 UTC|newest] Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-11-15 11:20 [PATCH v2 1/1] PCI: brcmstb: Use BIT() as __GENMASK() is for internal use only Andy Shevchenko 2021-11-15 11:20 ` Andy Shevchenko 2021-11-15 11:57 ` Krzysztof Wilczyński 2021-11-15 11:57 ` Krzysztof Wilczyński 2021-11-15 13:59 ` Robin Murphy 2021-11-15 13:59 ` Robin Murphy 2021-11-15 14:14 ` Andy Shevchenko 2021-11-15 14:14 ` Andy Shevchenko 2021-11-15 14:39 ` Andy Shevchenko [this message] 2021-11-15 14:39 ` Andy Shevchenko 2021-11-16 18:20 ` Rob Herring 2021-11-16 18:20 ` Rob Herring 2021-11-16 20:41 ` Florian Fainelli 2021-11-16 20:41 ` Florian Fainelli 2021-11-16 20:56 ` Florian Fainelli 2021-11-16 20:56 ` Florian Fainelli 2021-11-17 10:37 ` Andy Shevchenko 2021-11-17 10:37 ` Andy Shevchenko 2021-11-17 22:46 ` Rob Herring 2021-11-17 22:46 ` Rob Herring 2021-11-16 20:38 ` Florian Fainelli 2021-11-16 20:38 ` Florian Fainelli 2021-11-17 12:42 ` Andy Shevchenko 2021-11-17 12:42 ` Andy Shevchenko 2021-12-01 15:53 ` Lorenzo Pieralisi 2021-12-01 15:53 ` Lorenzo Pieralisi 2021-12-01 16:01 ` Andy Shevchenko 2021-12-01 16:01 ` Andy Shevchenko 2021-12-01 17:13 ` Lorenzo Pieralisi 2021-12-01 17:13 ` Lorenzo Pieralisi
Reply instructions: You may reply publicly to this message via plain-text email using any one of the following methods: * Save the following mbox file, import it into your mail client, and reply-to-all from there: mbox Avoid top-posting and favor interleaved quoting: https://en.wikipedia.org/wiki/Posting_style#Interleaved_style * Reply using the --to, --cc, and --in-reply-to switches of git-send-email(1): git send-email \ --in-reply-to=YZJxG7JFAfIqr1/f@smile.fi.intel.com \ --to=andriy.shevchenko@linux.intel.com \ --cc=bcm-kernel-feedback-list@broadcom.com \ --cc=bhelgaas@google.com \ --cc=f.fainelli@gmail.com \ --cc=jim2101024@gmail.com \ --cc=kw@linux.com \ --cc=linux-arm-kernel@lists.infradead.org \ --cc=linux-kernel@vger.kernel.org \ --cc=linux-pci@vger.kernel.org \ --cc=linux-rpi-kernel@lists.infradead.org \ --cc=lorenzo.pieralisi@arm.com \ --cc=nsaenz@kernel.org \ --cc=robh@kernel.org \ --cc=robin.murphy@arm.com \ /path/to/YOUR_REPLY https://kernel.org/pub/software/scm/git/docs/git-send-email.html * If your mail client supports setting the In-Reply-To header via mailto: links, try the mailto: linkBe sure your reply has a Subject: header at the top and a blank line before the message body.
This is an external index of several public inboxes, see mirroring instructions on how to clone and mirror all data and code used by this external index.