Re: [RFC 5/5] [powerpc] Implement a p1010rdb clock source.

[Wolfgang Grandegger <wg-5Yr1BZd7O62+XT7JhA+gdA@public.gmane.org>]

On 08/08/2011 05:25 PM, Robin Holt wrote:
> On Mon, Aug 08, 2011 at 05:18:57PM +0200, Wolfgang Grandegger wrote:
>> On 08/08/2011 05:09 PM, Robin Holt wrote:
>>> On Mon, Aug 08, 2011 at 04:59:54PM +0200, Wolfgang Grandegger wrote:
>>>> On 08/08/2011 04:44 PM, Robin Holt wrote:
>>>>> On Mon, Aug 08, 2011 at 04:37:44PM +0200, Wolfgang Grandegger wrote:
>>>>>> On 08/08/2011 04:21 PM, Robin Holt wrote:
>>>>>>> On Mon, Aug 08, 2011 at 04:16:27PM +0200, Wolfgang Grandegger wrote:
>>>>>>>> On 08/08/2011 03:56 PM, Robin Holt wrote:
>>>>>>>>>> commit 65bb8b060a873fa4f5188f2951081f6011259614
>>>>>>>>>> Author: Bhaskar Upadhaya <Bhaskar.Upadhaya-KZfg59tc24xl57MIdRCFDg@public.gmane.org>
>>>>>>>>>> Date:   Fri Mar 4 20:27:58 2011 +0530
>>>>>>>>>
>>>>>>>>> On a side note, that commit fixes up "fsl,flexcan-v1.0"
>>>>>>>>> ...
>>>>>>>>> +       do_fixup_by_compat_u32(blob, "fsl,flexcan-v1.0",
>>>>>>>>> +                       "clock_freq", gd->bus_clk, 1);
>>>>>>>>>
>>>>>>>>> Should I go back to flexcan-v1.0 in my patches?
>>>>>>>>
>>>>>>>> Well, no. Let's wait. I don't think we need it. Also, it sets
>>>>>>>> "clock_freq" while
>>>>>>>>
>>>>>>>>  http://lxr.linux.no/#linux+v3.0.1/Documentation/devicetree/bindings/net/can/fsl-flexcan.txt
>>>>>>>>
>>>>>>>> documents "clock-frequencies"... :-(.
>>>>>>>
>>>>>>> You answered a different question that I was asking.  I was asking if
>>>>>>> I should change fsl,flexcan back to fsl,flexcan-v1.0 as documented on
>>>>>>> line 5.  The clock_freq looks like a uboot change will need to be made
>>>>>>> as well.
>>>>>>
>>>>>> Well, I wrote above: "Well, no. Let's wait. I don't think we need it."
>>>>>>
>>>>>> For the P1010 we can sinmply derive the clock frequency from
>>>>>> "fsl_get_sys_freq()", which is fine for the time being. No extra
>>>>>> properties, etc. The clk implemetation might go into
>>>>>>
>>>>>>  http://lxr.linux.no/#linux+v3.0.1/arch/powerpc/platforms/85xx/clock.c
>>>>>>
>>>>>> or
>>>>>>
>>>>>>  http://lxr.linux.no/#linux+v3.0.1/arch/powerpc/sysdev/fsl_soc.c
>>>>>>
>>>>>> And may depend on HAVE_CAN_FLEXCAN
>>>>>>
>>>>>> BTW, I have not found HAVE_CAN_FLEXCAN in your patch. What kernel are
>>>>>> you using?
>>>>>
>>>>> I am starting with the v3.0 kernel, apply one patch from the freescale BSP
>>>>> we receive under NDA which introduces the P1010RDB board into the QorIQ
>>>>> platform, and then work from there for the flexcan stuff.  That patch
>>>>> introduces the HAVE_CAN_FLEXCAN.  I do not like how freescale structured
>>>>> that Kconfig bit, so I have tweaked it to be selected automatically
>>>>> when P1010RDB, NET, and CAN are selected.  That allows the CAN_FLEXCAN
>>>>> selection to determine is we are going to build the flexcan.c file.
>>>>
>>>> ARM boards select HAVE_CAN_FLEXCAN and I do not see a good reason why
>>>> we should do it differently for PowerPC. 
>>>>
>>>> For mainline inclusion, you should provide your patches against the
>>>> David Millers "net-next-2.6" tree, which already seems to have support
>>>> for the P1010RDB:
>>>>
>>>>   config P1010_RDB
>>>>         bool "Freescale P1010RDB"
>>>>         select DEFAULT_UIMAGE
>>>>         help
>>>>           This option enables support for the MPC85xx RDB (P1010 RDB) board
>>>>
>>>>           P1010RDB contains P1010Si, which provides CPU performance up to 800
>>>>           MHz and 1600 DMIPS, additional functionality and faster interfaces
>>>>           (DDR3/3L, SATA II, and PCI  Express).
>>>>
>>>>
>>>>> Our contact with Freescale would prefer that I not post that patch until
>>>>> we get the OK from freescale to do so since we received it under NDA.
>>>>
>>>> I don't think we currently need it. I prefer dropping and cleaning up
>>>> the device tree stuff as it is not needed for the P1010 anyway. If a
>>>> new processor shows up with enhanced capabilities requiring
>>>> configuration via device tree, we or somebody else can provide a patch.
>>>> Marc, what do you think?
>>>
>>> I will rebase shortly and provide a newer set of patches.
>>>
>>> I do think powerpc does need the device tree support.  That is how the flexcan_probe
>>> is getting called.  How would you suggest I do it otherwise?
>>
>> Why do you think that?
> 
> In patch 3/5 in this series (attached below), I made a change in how
> device discovery works.  Without that of_match stuff, the flexcan
> driver was never getting its flexcan_probe function called.  As soon
> as I added that, it worked.  Looking at the driver_register path, this
> appeared to be the "correct" way to implement the device discovery.
> Did I miss something?

I already clarified my statement. Hope you agree now.

Wolfgang.