From mboxrd@z Thu Jan  1 00:00:00 1970
From: Wolfram Sang <wsa@the-dreams.de>
Subject: Re: [RFC 2/2] i2c: sh_mobile: rework deferred probing
Date: Tue, 16 Dec 2014 12:35:23 +0100
Message-ID: <20141216113523.GB10958@katana>
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To: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Linux I2C <linux-i2c@vger.kernel.org>, Linux-sh list <linux-sh@vger.kernel.org>, Magnus Damm <magnus.damm@gmail.com>, Simon Horman <horms@verge.net.au>, Laurent Pinchart <laurent.pinchart@ideasonboard.com>
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On Wed, Dec 10, 2014 at 02:44:58PM +0100, Geert Uytterhoeven wrote:
> Hi Wolfram,
>=20
> On Wed, Dec 10, 2014 at 2:21 PM, Wolfram Sang <wsa@the-dreams.de> wrote:
> > DMA is opt-in for this driver. So, we can't use deferred probing in
> > probe, because our driver would get endlessly deferred if DMA support is
> > compiled in but only the DMA driver is missing. Because we can't know
> > when the DMA driver might show up, we always try again when a DMA
> > transfer would be possible. The downside is that there is more overhead
> > for setting up every DMA transfer.
>=20
> ... for setting up every PIO transfer?
>=20
> Once DMA is available, it's just one extra variable check.

ACK. Mixed that up.

>=20
> > Reported-by: Geert Uytterhoeven <geert+renesas@glider.be>
> > Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
> > ---
> >  drivers/i2c/busses/i2c-sh_mobile.c | 98 +++++++++++++++++++-----------=
--------
> >  1 file changed, 48 insertions(+), 50 deletions(-)
> >
> > diff --git a/drivers/i2c/busses/i2c-sh_mobile.c b/drivers/i2c/busses/i2=
c-sh_mobile.c
> > index 636f2297143a..ea7b99212fa6 100644
> > --- a/drivers/i2c/busses/i2c-sh_mobile.c
> > +++ b/drivers/i2c/busses/i2c-sh_mobile.c
> > @@ -144,6 +144,7 @@ struct sh_mobile_i2c_data {
> >         int sr;
> >         bool send_stop;
> >
> > +       struct resource *res;
>=20
> I thinkk you can just store dma_addr_t port_addr here.

Yes, but I liked the resource better :)


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