From: Geert Uytterhoeven <geert@linux-m68k.org> To: Johannes Berg <johannes@sipsolutions.net> Cc: Tony Lindgren <tony@atomide.com>, Russell King <linux@armlinux.org.uk>, Rajendra Nayak <rnayak@codeaurora.org>, Paul Walmsley <paul@pwsan.com>, Michael Turquette <mturquette@baylibre.com>, Stephen Boyd <sboyd@kernel.org>, Nicolas Ferre <nicolas.ferre@microchip.com>, Alexandre Belloni <alexandre.belloni@bootlin.com>, Ludovic Desroches <ludovic.desroches@microchip.com>, Tero Kristo <kristo@kernel.org>, Jonathan Cameron <jic23@kernel.org>, Lars-Peter Clausen <lars@metafoo.de>, Lorenzo Bianconi <lorenzo.bianconi83@gmail.com>, Benoit Parrot <bparrot@ti.com>, Mauro Carvalho Chehab <mchehab@kernel.org>, Adrian Hunter <adrian.hunter@intel.com>, Andrew Jeffery <andrew@aj.id.au>, Ulf Hansson <ulf.hansson@linaro.org>, Joel Stanley <joel@jms.id.au>, Ping-Ke Shih <pkshih@realtek.com>, Kalle Valo <kvalo@codeaurora.org>, "David S . Miller" <davem@davemloft.net>, Jakub Kicinski <kuba@kernel.org>, Linus Walleij <linus.walleij@linaro.org>, Liam Girdwood <lgirdwood@gmail.com>, Mark Brown <broonie@kernel.org>, Magnus Damm <magnus.damm@gmail.com>, Eduardo Valentin <edubezval@gmail.com>, Keerthy <j-keerthy@ti.com>, "Rafael J . Wysocki" <rafael@kernel.org>, Daniel Lezcano <daniel.lezcano@linaro.org>, Amit Kucheria <amitk@kernel.org>, Zhang Rui <rui.zhang@intel.com>, Jaroslav Kysela <perex@perex.cz>, Takashi Iwai <tiwai@suse.com>, linux-arm-kernel@lists.infradead.org, linux-omap@vger.kernel.org, linux-kernel@vger.kernel.org, linux-clk@vger.kernel.org, linux-renesas-soc@vger.kernel.org, linux-iio@vger.kernel.org, linux-media@vger.kernel.org, linux-mmc@vger.kernel.org, linux-aspeed@lists.ozlabs.org, openbmc@lists.ozlabs.org, linux-wireless@vger.kernel.org, netdev@vger.kernel.org, linux-gpio@vger.kernel.org, linux-pm@vger.kernel.org, alsa-devel@alsa-project.org Subject: Re: [PATCH 01/17] bitfield: Add non-constant field_{prep,get}() helpers Date: Tue, 23 Nov 2021 09:30:14 +0100 [thread overview] Message-ID: <CAMuHMdUnBgFpqhgjf5AA0LH9MZOFALeC=YinZ4Tv_V+Y9hkRSg@mail.gmail.com> (raw) In-Reply-To: <01b44b38c087c151171f8d45a2090474c2559306.camel@sipsolutions.net> Hi Johannes, On Mon, Nov 22, 2021 at 5:33 PM Johannes Berg <johannes@sipsolutions.net> wrote: > On Mon, 2021-11-22 at 16:53 +0100, Geert Uytterhoeven wrote: > > The existing FIELD_{GET,PREP}() macros are limited to compile-time > > constants. However, it is very common to prepare or extract bitfield > > elements where the bitfield mask is not a compile-time constant. > > > > I'm not sure it's really a good idea to add a third API here? > > We have the upper-case (constant) versions, and already > {u32,...}_get_bits()/etc. These don't work for non-const masks. > Also, you're using __ffs(), which doesn't work for 64-bit on 32-bit > architectures (afaict), so that seems a bit awkward. That's a valid comment. Can be fixed by using a wrapper macro that checks if typeof(mask) == u64, and uses an __ffs64() version when needed. > Maybe we can make {u32,...}_get_bits() be doing compile-time only checks > if it is indeed a constant? The __field_overflow() usage is already only > done if __builtin_constant_p(v), so I guess we can do the same with > __bad_mask()? Are all compilers smart enough to replace the division by field_multiplier(field) by a shift? Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-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
WARNING: multiple messages have this Message-ID (diff)
From: Geert Uytterhoeven <geert@linux-m68k.org> To: Johannes Berg <johannes@sipsolutions.net> Cc: Alexandre Belloni <alexandre.belloni@bootlin.com>, Daniel Lezcano <daniel.lezcano@linaro.org>, linux-aspeed@lists.ozlabs.org, Liam Girdwood <lgirdwood@gmail.com>, Tony Lindgren <tony@atomide.com>, linux-wireless@vger.kernel.org, Michael Turquette <mturquette@baylibre.com>, Amit Kucheria <amitk@kernel.org>, Ulf Hansson <ulf.hansson@linaro.org>, Adrian Hunter <adrian.hunter@intel.com>, linux-clk@vger.kernel.org, Ping-Ke Shih <pkshih@realtek.com>, Lars-Peter Clausen <lars@metafoo.de>, openbmc@lists.ozlabs.org, "Rafael J . Wysocki" <rafael@kernel.org>, Magnus Damm <magnus.damm@gmail.com>, Russell King <linux@armlinux.org.uk>, linux-iio@vger.kernel.org, Ludovic Desroches <ludovic.desroches@microchip.com>, Joel Stanley <joel@jms.id.au>, Jakub Kicinski <kuba@kernel.org>, Zhang Rui <rui.zhang@intel.com>, Linus Walleij <linus.walleij@linaro.org>, linux-media@vger.kernel.org, alsa-devel@alsa-project.org, linux-omap@vger.kernel.org, Benoit Parrot <bparrot@ti.com>, linux-gpio@vger.kernel.org, Mark Brown <broonie@kernel.org>, Lorenzo Bianconi <lorenzo.bianconi83@gmail.com>, Takashi Iwai <tiwai@suse.com>, Mauro Carvalho Chehab <mchehab@kernel.org>, Kalle Valo <kvalo@codeaurora.org>, linux-arm-kernel@lists.infradead.org, Eduardo Valentin <edubezval@gmail.com>, Paul Walmsley <paul@pwsan.com>, Rajendra Nayak <rnayak@codeaurora.org>, Tero Kristo <kristo@kernel.org>, Andrew Jeffery <andrew@aj.id.au>, Keerthy <j-keerthy@ti.com>, linux-pm@vger.kernel.org, linux-mmc@vger.kernel.org, Nicolas Ferre <nicolas.ferre@microchip.com>, linux-kernel@vger.kernel.org, linux-renesas-soc@vger.kernel.org, Stephen Boyd <sboyd@kernel.org>, netdev@vger.kernel.org, "David S . Miller" <davem@davemloft.net>, Jonathan Cameron <jic23@kernel.org> Subject: Re: [PATCH 01/17] bitfield: Add non-constant field_{prep, get}() helpers Date: Tue, 23 Nov 2021 09:30:14 +0100 [thread overview] Message-ID: <CAMuHMdUnBgFpqhgjf5AA0LH9MZOFALeC=YinZ4Tv_V+Y9hkRSg@mail.gmail.com> (raw) In-Reply-To: <01b44b38c087c151171f8d45a2090474c2559306.camel@sipsolutions.net> Hi Johannes, On Mon, Nov 22, 2021 at 5:33 PM Johannes Berg <johannes@sipsolutions.net> wrote: > On Mon, 2021-11-22 at 16:53 +0100, Geert Uytterhoeven wrote: > > The existing FIELD_{GET,PREP}() macros are limited to compile-time > > constants. However, it is very common to prepare or extract bitfield > > elements where the bitfield mask is not a compile-time constant. > > > > I'm not sure it's really a good idea to add a third API here? > > We have the upper-case (constant) versions, and already > {u32,...}_get_bits()/etc. These don't work for non-const masks. > Also, you're using __ffs(), which doesn't work for 64-bit on 32-bit > architectures (afaict), so that seems a bit awkward. That's a valid comment. Can be fixed by using a wrapper macro that checks if typeof(mask) == u64, and uses an __ffs64() version when needed. > Maybe we can make {u32,...}_get_bits() be doing compile-time only checks > if it is indeed a constant? The __field_overflow() usage is already only > done if __builtin_constant_p(v), so I guess we can do the same with > __bad_mask()? Are all compilers smart enough to replace the division by field_multiplier(field) by a shift? Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-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
next prev parent reply other threads:[~2021-11-23 8:30 UTC|newest] Thread overview: 77+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-11-22 15:53 [PATCH 00/17] Non-const bitfield helper conversions Geert Uytterhoeven 2021-11-22 15:53 ` Geert Uytterhoeven 2021-11-22 15:53 ` [PATCH 01/17] bitfield: Add non-constant field_{prep,get}() helpers Geert Uytterhoeven 2021-11-22 15:53 ` Geert Uytterhoeven 2021-11-22 16:32 ` Johannes Berg 2021-11-22 16:32 ` Johannes Berg 2021-11-23 1:17 ` Jakub Kicinski 2021-11-23 1:17 ` Jakub Kicinski 2021-11-23 8:36 ` Geert Uytterhoeven 2021-11-23 8:36 ` [PATCH 01/17] bitfield: Add non-constant field_{prep, get}() helpers Geert Uytterhoeven 2021-11-23 16:24 ` [PATCH 01/17] bitfield: Add non-constant field_{prep,get}() helpers Johannes Berg 2021-11-23 16:24 ` Johannes Berg 2021-11-23 23:49 ` Jakub Kicinski 2021-11-23 23:49 ` Jakub Kicinski 2021-11-24 8:03 ` Johannes Berg 2021-11-24 13:59 ` Jakub Kicinski 2021-11-24 14:07 ` Johannes Berg 2021-11-23 23:39 ` Jakub Kicinski 2021-11-23 23:39 ` Jakub Kicinski 2021-11-23 1:52 ` Alex Elder 2021-11-23 1:52 ` Alex Elder 2021-11-23 8:38 ` Geert Uytterhoeven 2021-11-23 8:38 ` [PATCH 01/17] bitfield: Add non-constant field_{prep, get}() helpers Geert Uytterhoeven 2021-11-23 8:30 ` Geert Uytterhoeven [this message] 2021-11-23 8:30 ` Geert Uytterhoeven 2021-11-23 16:21 ` [PATCH 01/17] bitfield: Add non-constant field_{prep,get}() helpers Johannes Berg 2021-11-23 16:21 ` Johannes Berg 2021-11-23 16:31 ` Geert Uytterhoeven 2021-11-23 16:31 ` [PATCH 01/17] bitfield: Add non-constant field_{prep, get}() helpers Geert Uytterhoeven 2021-11-24 8:24 ` [PATCH 01/17] bitfield: Add non-constant field_{prep,get}() helpers Kalle Valo 2021-11-22 15:53 ` [PATCH 02/17] clk: renesas: Use bitfield helpers Geert Uytterhoeven 2021-11-22 15:53 ` Geert Uytterhoeven 2021-11-22 15:53 ` [PATCH/RFC 03/17] soc: " Geert Uytterhoeven 2021-11-22 15:53 ` Geert Uytterhoeven 2021-11-22 15:53 ` [PATCH/RFC 04/17] ARM: OMAP2+: " Geert Uytterhoeven 2021-11-22 15:53 ` Geert Uytterhoeven 2021-11-22 15:53 ` [PATCH/RFC 05/17] bus: omap_l3_noc: " Geert Uytterhoeven 2021-11-22 15:53 ` Geert Uytterhoeven 2021-11-22 15:53 ` [PATCH/RFC 06/17] clk: ti: " Geert Uytterhoeven 2021-11-22 15:53 ` Geert Uytterhoeven 2021-11-22 15:54 ` [PATCH/RFC 07/17] iio: st_sensors: " Geert Uytterhoeven 2021-11-22 15:54 ` Geert Uytterhoeven 2021-11-23 23:35 ` Linus Walleij 2021-11-23 23:35 ` Linus Walleij 2021-11-22 15:54 ` [PATCH/RFC 08/17] iio: humidity: hts221: " Geert Uytterhoeven 2021-11-22 15:54 ` Geert Uytterhoeven 2021-11-24 15:21 ` Jonathan Cameron 2021-11-22 15:54 ` [PATCH/RFC 09/17] iio: imu: st_lsm6dsx: " Geert Uytterhoeven 2021-11-22 15:54 ` Geert Uytterhoeven 2021-11-22 15:54 ` [PATCH/RFC 10/17] media: ti-vpe: cal: " Geert Uytterhoeven 2021-11-22 15:54 ` Geert Uytterhoeven 2021-11-22 15:54 ` [PATCH/RFC 11/17] mmc: sdhci-of-aspeed: " Geert Uytterhoeven 2021-11-22 15:54 ` Geert Uytterhoeven 2021-11-22 15:54 ` [PATCH/RFC 12/17] pinctrl: aspeed: " Geert Uytterhoeven 2021-11-22 15:54 ` Geert Uytterhoeven 2021-11-22 15:54 ` [PATCH/RFC 13/17] pinctl: ti: iodelay: " Geert Uytterhoeven 2021-11-22 15:54 ` Geert Uytterhoeven 2021-11-22 17:52 ` Alexandre Belloni 2021-11-22 17:52 ` Alexandre Belloni 2021-11-22 15:54 ` [PATCH/RFC 14/17] regulator: ti-abb: " Geert Uytterhoeven 2021-11-22 15:54 ` Geert Uytterhoeven 2021-11-22 16:31 ` Mark Brown 2021-11-22 16:31 ` Mark Brown 2021-11-22 15:54 ` [PATCH/RFC 15/17] thermal/ti-soc-thermal: " Geert Uytterhoeven 2021-11-22 15:54 ` Geert Uytterhoeven 2021-11-22 15:54 ` [PATCH/RFC 16/17] ALSA: ice1724: " Geert Uytterhoeven 2021-11-22 15:54 ` Geert Uytterhoeven 2021-11-23 11:24 ` Takashi Iwai 2021-11-23 11:24 ` Takashi Iwai 2021-11-22 15:54 ` [PATCH/RFC 17/17] rtw89: " Geert Uytterhoeven 2021-11-22 15:54 ` Geert Uytterhoeven 2021-11-22 18:38 ` Larry Finger 2021-11-22 18:38 ` Larry Finger 2021-11-22 17:50 ` [PATCH 00/17] Non-const bitfield helper conversions Alexandre Belloni 2021-11-22 17:50 ` Alexandre Belloni 2021-11-23 8:20 ` Geert Uytterhoeven 2021-11-23 8:20 ` Geert Uytterhoeven
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