From mboxrd@z Thu Jan 1 00:00:00 1970 From: Lee Jones Date: Mon, 14 Oct 2019 07:27:45 +0000 Subject: Re: [PATCH v2 4/4] backlight: pwm_bl: switch to power-of-2 base for fixed-point math Message-Id: <20191014072745.GH4545@dell> List-Id: References: <20191008120327.24208-1-linux@rasmusvillemoes.dk> <20191008120327.24208-5-linux@rasmusvillemoes.dk> In-Reply-To: <20191008120327.24208-5-linux@rasmusvillemoes.dk> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit To: Rasmus Villemoes Cc: Thierry Reding , Uwe =?iso-8859-1?Q?Kleine-K=F6nig?= , Daniel Thompson , Jingoo Han , Bartlomiej Zolnierkiewicz , linux-pwm@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-fbdev@vger.kernel.org, linux-kernel@vger.kernel.org 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 > Signed-off-by: Rasmus Villemoes > --- > 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