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From: Johannes Berg <johannes@sipsolutions.net>
To: Geert Uytterhoeven <geert+renesas@glider.be>,
	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>
Cc: 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: Mon, 22 Nov 2021 17:32:43 +0100	[thread overview]
Message-ID: <01b44b38c087c151171f8d45a2090474c2559306.camel@sipsolutions.net> (raw)
In-Reply-To: <3a54a6703879d10f08cf0275a2a69297ebd2b1d4.1637592133.git.geert+renesas@glider.be>

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.

Also, you're using __ffs(), which doesn't work for 64-bit on 32-bit
architectures (afaict), so that seems a bit awkward.

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()?

johannes

WARNING: multiple messages have this Message-ID (diff)
From: Johannes Berg <johannes@sipsolutions.net>
To: Geert Uytterhoeven <geert+renesas@glider.be>,
	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>
Cc: alsa-devel@alsa-project.org, linux-aspeed@lists.ozlabs.org,
	linux-pm@vger.kernel.org, linux-iio@vger.kernel.org,
	linux-wireless@vger.kernel.org, openbmc@lists.ozlabs.org,
	linux-mmc@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-renesas-soc@vger.kernel.org, linux-gpio@vger.kernel.org,
	netdev@vger.kernel.org, linux-omap@vger.kernel.org,
	linux-clk@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	linux-media@vger.kernel.org
Subject: Re: [PATCH 01/17] bitfield: Add non-constant field_{prep,get}() helpers
Date: Mon, 22 Nov 2021 17:32:43 +0100	[thread overview]
Message-ID: <01b44b38c087c151171f8d45a2090474c2559306.camel@sipsolutions.net> (raw)
In-Reply-To: <3a54a6703879d10f08cf0275a2a69297ebd2b1d4.1637592133.git.geert+renesas@glider.be>

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.

Also, you're using __ffs(), which doesn't work for 64-bit on 32-bit
architectures (afaict), so that seems a bit awkward.

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()?

johannes

  reply	other threads:[~2021-11-22 16:34 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 [this message]
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     ` [PATCH 01/17] bitfield: Add non-constant field_{prep,get}() helpers Geert Uytterhoeven
2021-11-23  8:30       ` [PATCH 01/17] bitfield: Add non-constant field_{prep, get}() helpers 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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