From: Robin Holt <holt-sJ/iWh9BUns@public.gmane.org>
To: Kumar Gala <galak-XVmvHMARGAS8U2dJNN8I7kB+6BGkLq7r@public.gmane.org>
Cc: netdev-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
U Bhaskar-B22300 <B22300-KZfg59tc24xl57MIdRCFDg@public.gmane.org>,
socketcan-core-0fE9KPoRgkgATYTw5x5z8w@public.gmane.org,
PPC list <linuxppc-dev-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org>,
Wolfgang Grandegger <wg-5Yr1BZd7O62+XT7JhA+gdA@public.gmane.org>
Subject: Re: [PATCH v11 4/5] powerpc: Add flexcan device support for p1010rdb.
Date: Thu, 11 Aug 2011 05:42:52 -0500 [thread overview]
Message-ID: <20110811104252.GC4926@sgi.com> (raw)
In-Reply-To: <634AB7A6-1CDA-41B3-8A5D-01F29EF01521-XVmvHMARGAS8U2dJNN8I7kB+6BGkLq7r@public.gmane.org>
On Wed, Aug 10, 2011 at 11:46:27PM -0500, Kumar Gala wrote:
>
> On Aug 10, 2011, at 1:16 PM, Wolfgang Grandegger wrote:
>
> > On 08/10/2011 07:01 PM, Kumar Gala wrote:
> >>
> >> On Aug 10, 2011, at 11:27 AM, Robin Holt wrote:
> >>
> >>> I added a simple clock source for the p1010rdb so the flexcan driver
> >>> could determine a clock frequency. The p1010 flexcan device only has
> >>> an oscillator of system bus frequency divided by 2.
> >>>
> >>> Signed-off-by: Robin Holt <holt-sJ/iWh9BUns@public.gmane.org>
> >>> Acked-by: Marc Kleine-Budde <mkl-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>,
> >>> Acked-by: Wolfgang Grandegger <wg-5Yr1BZd7O62+XT7JhA+gdA@public.gmane.org>,
> >>> Cc: U Bhaskar-B22300 <B22300-KZfg59tc24xl57MIdRCFDg@public.gmane.org>
> >>> Cc: socketcan-core-0fE9KPoRgkgATYTw5x5z8w@public.gmane.org,
> >>> Cc: netdev-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
> >>> Cc: PPC list <linuxppc-dev-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org>
> >>> Cc: Kumar Gala <galak-XVmvHMARGAS8U2dJNN8I7kB+6BGkLq7r@public.gmane.org>
> >>> ---
> >>> arch/powerpc/platforms/85xx/Kconfig | 2 +
> >>> arch/powerpc/platforms/85xx/Makefile | 2 +
> >>> arch/powerpc/platforms/85xx/clock.c | 52 ++++++++++++++++++++++++++++++++
> >>> arch/powerpc/platforms/85xx/p1010rdb.c | 8 +++++
> >>> 4 files changed, 64 insertions(+), 0 deletions(-)
> >>> create mode 100644 arch/powerpc/platforms/85xx/clock.c
> >>
> >> I dont understand how mpc85xx_clk_functions() ends up being associated with the frequency the flexcan is running at.
> >
> > The function mpc85xx_clk_get_rate() returns "fsl_get_sys_freq() / 2" for
> > Flexcan devices.
> >
> >> This either seems to global or I'm missing something.
> >
> > This patch extends the existing Flexcan platform driver for ARM for the
> > PowerPC using the device tree. Due to the nice integration of the device
> > tree (of-platform) into the platform driver and devices, the difference
> > are quite small (see patches 1..3). Apart from the endianess issue, only
> > the clock needs to be handled in a common way. As ARM already uses the
> > clk interface, we found it straight-forward to implement it for the
> > P1010, or more general for the 85xx, as well, instead of using an
> > additional helper function.
>
> I see, that. What concerns me is there are numerous clocks /
> frequencies that exist inside a MPC85xx/P1010 SOC. The code I'm seeing
> does NOT seem to do anything to relate this clock JUST to the flexcan.
if (!dev->of_node ||
!of_device_is_compatible(dev->of_node, "fsl,flexcan"))
return ERR_PTR(-ENOENT);
That should relate it just to flexcan, right? Plus it has the added
benefit of being a baby-step in the direction of implementing a clkdev
type thing for powerpc which did look fairly slick to me, but I may
be confused.
It sounds like Wolfgang is defering to you. Give it an honest evaluation
and tell me which direction you would like me to go. I don't have a
strong preference either way. The alternative I gave to Wolfgang of
using a flexcan property to avoid needing any clk_get_rate seems fairly
hackish at this point, but I have had more time to get used to the
'hack in a 85xx clock' method.
Thanks,
Robin
next prev parent reply other threads:[~2011-08-11 10:42 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-08-10 16:27 [PATCH v11 0/5] flexcan/powerpc: Add support for powerpc flexcan (freescale p1010) Robin Holt
2011-08-10 16:27 ` [PATCH v11 2/5] flexcan: Abstract off read/write for big/little endian Robin Holt
[not found] ` <1312993670-23999-1-git-send-email-holt-sJ/iWh9BUns@public.gmane.org>
2011-08-10 16:27 ` [PATCH v11 1/5] flexcan: Remove #include <mach/clock.h> Robin Holt
2011-08-10 16:27 ` [PATCH v11 3/5] flexcan: Add of_match to platform_device definition Robin Holt
2011-08-10 16:27 ` [PATCH v11 4/5] powerpc: Add flexcan device support for p1010rdb Robin Holt
[not found] ` <1312993670-23999-5-git-send-email-holt-sJ/iWh9BUns@public.gmane.org>
2011-08-10 17:01 ` Kumar Gala
[not found] ` <8E5FA886-038D-4DF4-8A54-DD60188A21A2-XVmvHMARGAS8U2dJNN8I7kB+6BGkLq7r@public.gmane.org>
2011-08-10 18:16 ` Wolfgang Grandegger
[not found] ` <4E42CB01.7030700-5Yr1BZd7O62+XT7JhA+gdA@public.gmane.org>
2011-08-11 3:56 ` Robin Holt
[not found] ` <20110811035620.GB4926-sJ/iWh9BUns@public.gmane.org>
2011-08-11 7:35 ` Wolfgang Grandegger
2011-08-11 4:46 ` Kumar Gala
[not found] ` <634AB7A6-1CDA-41B3-8A5D-01F29EF01521-XVmvHMARGAS8U2dJNN8I7kB+6BGkLq7r@public.gmane.org>
2011-08-11 7:26 ` Wolfgang Grandegger
2011-08-11 10:42 ` Robin Holt [this message]
[not found] ` <20110811104252.GC4926-sJ/iWh9BUns@public.gmane.org>
2011-08-11 14:17 ` Kumar Gala
2011-08-10 16:27 ` [PATCH v11 5/5] powerpc: Fix up fsl-flexcan device tree binding Robin Holt
2011-08-10 16:56 ` Scott Wood
[not found] ` <4E42B83C.2040705-KZfg59tc24xl57MIdRCFDg@public.gmane.org>
2011-08-10 17:19 ` Robin Holt
2011-08-10 17:36 ` Scott Wood
[not found] ` <4E42C196.7030708-KZfg59tc24xl57MIdRCFDg@public.gmane.org>
2011-08-10 18:30 ` Robin Holt
2011-08-10 18:40 ` Scott Wood
[not found] ` <4E42D09E.4080405-KZfg59tc24xl57MIdRCFDg@public.gmane.org>
2011-08-10 18:45 ` Robin Holt
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