From: Wolfram Sang <wsa-z923LK4zBo2bacvFa/9K2g@public.gmane.org>
To: Laurent Pinchart
<laurent.pinchart-ryLnwIuWjnjg/C1BVhZhaw@public.gmane.org>
Cc: linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
linux-sh-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
Magnus Damm <magnus.damm-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>,
Simon Horman <horms-/R6kz+dDXgpPR4JQBCEnsQ@public.gmane.org>,
Geert Uytterhoeven
<geert-Td1EMuHUCqxL1ZNQvxDV9g@public.gmane.org>
Subject: Re: [RFC 0/3] i2c: sh_mobile: add DMA support
Date: Sun, 2 Nov 2014 22:53:59 +0100 [thread overview]
Message-ID: <20141102215359.GA1278@katana> (raw)
In-Reply-To: <21770791.t5tSlWMt1c@avalon>
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> > Here is my RFC to support DMA with the i2c-sh_mobile core. DMA works nicely
> > with my tests so far and we save 1 interrupt per transferred byte, yay!
>
> Do we have an idea of how much power (or CPU time ?) DMA support could save ?
I have some numbers from the function tracer, but I don't trust them.
According to them, DMA is always better (50us per interrupt vs. 23us for
DMA setup). This is why I say the threshold is still under test.
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WARNING: multiple messages have this Message-ID (diff)
From: Wolfram Sang <wsa@the-dreams.de>
To: Laurent Pinchart
<laurent.pinchart-ryLnwIuWjnjg/C1BVhZhaw@public.gmane.org>
Cc: linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
linux-sh-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
Magnus Damm <magnus.damm-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>,
Simon Horman <horms-/R6kz+dDXgpPR4JQBCEnsQ@public.gmane.org>,
Geert Uytterhoeven
<geert-Td1EMuHUCqxL1ZNQvxDV9g@public.gmane.org>
Subject: Re: [RFC 0/3] i2c: sh_mobile: add DMA support
Date: Sun, 02 Nov 2014 21:53:59 +0000 [thread overview]
Message-ID: <20141102215359.GA1278@katana> (raw)
In-Reply-To: <21770791.t5tSlWMt1c@avalon>
[-- Attachment #1: Type: text/plain, Size: 460 bytes --]
> > Here is my RFC to support DMA with the i2c-sh_mobile core. DMA works nicely
> > with my tests so far and we save 1 interrupt per transferred byte, yay!
>
> Do we have an idea of how much power (or CPU time ?) DMA support could save ?
I have some numbers from the function tracer, but I don't trust them.
According to them, DMA is always better (50us per interrupt vs. 23us for
DMA setup). This is why I say the threshold is still under test.
[-- Attachment #2: Digital signature --]
[-- Type: application/pgp-signature, Size: 819 bytes --]
next prev parent reply other threads:[~2014-11-02 21:53 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-10-31 10:51 [RFC 0/3] i2c: sh_mobile: add DMA support Wolfram Sang
2014-10-31 10:51 ` Wolfram Sang
2014-10-31 10:51 ` [RFC 1/3] " Wolfram Sang
2014-10-31 10:51 ` Wolfram Sang
2014-11-02 22:04 ` Laurent Pinchart
2014-11-02 22:04 ` Laurent Pinchart
2014-11-03 7:47 ` Wolfram Sang
2014-11-03 7:47 ` Wolfram Sang
2014-11-03 8:58 ` Geert Uytterhoeven
2014-11-03 8:58 ` Geert Uytterhoeven
[not found] ` <CAMuHMdX1-ANQQhZkfKG67-TSKEUO6sFeiUMkkA323Ww4Cw9JrA-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2014-11-04 10:19 ` Wolfram Sang
2014-11-04 10:19 ` Wolfram Sang
[not found] ` <1414752678-26078-1-git-send-email-wsa-z923LK4zBo2bacvFa/9K2g@public.gmane.org>
2014-10-31 10:51 ` [RFC 2/3] ARM: shmobile: r8a7790: add DMA nodes for IIC Wolfram Sang
2014-10-31 10:51 ` Wolfram Sang
[not found] ` <1414752678-26078-3-git-send-email-wsa-z923LK4zBo2bacvFa/9K2g@public.gmane.org>
2014-11-02 21:47 ` Laurent Pinchart
2014-11-02 21:47 ` Laurent Pinchart
2014-11-03 9:04 ` Geert Uytterhoeven
2014-11-03 9:04 ` Geert Uytterhoeven
2014-10-31 10:51 ` [RFC 3/3] ARM: shmobile: r8a7791: " Wolfram Sang
2014-10-31 10:51 ` Wolfram Sang
2014-11-02 21:47 ` Laurent Pinchart
2014-11-02 21:47 ` Laurent Pinchart
[not found] ` <1414752678-26078-4-git-send-email-wsa-z923LK4zBo2bacvFa/9K2g@public.gmane.org>
2014-11-03 9:04 ` Geert Uytterhoeven
2014-11-03 9:04 ` Geert Uytterhoeven
2014-11-02 21:14 ` [RFC 0/3] i2c: sh_mobile: add DMA support Laurent Pinchart
2014-11-02 21:14 ` Laurent Pinchart
2014-11-02 21:53 ` Wolfram Sang [this message]
2014-11-02 21:53 ` Wolfram Sang
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