From: Lee Jones <lee.jones@linaro.org>
To: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: "Thierry Reding" <thierry.reding@gmail.com>,
"Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>,
"Daniel Thompson" <daniel.thompson@linaro.org>,
"Jingoo Han" <jingoohan1@gmail.com>,
"Bartlomiej Zolnierkiewicz" <b.zolnierkie@samsung.com>,
linux-pwm@vger.kernel.org, dri-devel@lists.freedesktop.org,
linux-fbdev@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 4/4] backlight: pwm_bl: switch to power-of-2 base for fixed-point math
Date: Mon, 14 Oct 2019 07:27:45 +0000 [thread overview]
Message-ID: <20191014072745.GH4545@dell> (raw)
In-Reply-To: <20191008120327.24208-5-linux@rasmusvillemoes.dk>
On Tue, 08 Oct 2019, Rasmus Villemoes wrote:
> Using a power-of-2 instead of power-of-10 base makes the computations
> much cheaper. 2^16 is safe; retval never becomes more than 2^48 +
> 2^32/2. On a 32 bit platform, the very expensive 64/32 division at the
> end of cie1931() instead becomes essentially free (a shift by 32 is
> just a register rename).
>
> Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
> Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
> ---
> drivers/video/backlight/pwm_bl.c | 22 ++++++++++++----------
> 1 file changed, 12 insertions(+), 10 deletions(-)
Applied, thanks.
--
Lee Jones [李琼斯]
Linaro Services Technical Lead
Linaro.org │ Open source software for ARM SoCs
Follow Linaro: Facebook | Twitter | Blog
prev parent reply other threads:[~2019-10-14 7:27 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-08 12:03 [PATCH v2 0/4] backlight: pwm_bl: optimizations and small fix for cie1913 Rasmus Villemoes
2019-10-08 12:03 ` [PATCH v2 1/4] backlight: pwm_bl: fix cie1913 comments and constant Rasmus Villemoes
2019-10-14 7:27 ` Lee Jones
2019-10-23 20:21 ` Rasmus Villemoes
2019-10-08 12:03 ` [PATCH v2 2/4] backlight: pwm_bl: eliminate a 64/32 division Rasmus Villemoes
2019-10-14 7:27 ` Lee Jones
2019-10-08 12:03 ` [PATCH v2 3/4] backlight: pwm_bl: drop use of int_pow() Rasmus Villemoes
2019-10-14 7:27 ` Lee Jones
2019-10-08 12:03 ` [PATCH v2 4/4] backlight: pwm_bl: switch to power-of-2 base for fixed-point math Rasmus Villemoes
2019-10-14 7:27 ` Lee Jones [this message]
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