Freescale fec.c driver breakage

Freescale fec.c driver breakage

[Greg Ungerer]

Hi Sascha,

Commit f4d40de39a23f0c39cca55ac63e1175c69c3d2f7 ("net fec: do not
depend on grouped clocks") breaks compilation of the FEC driver for
non iMX platforms in linux-3.5-rc1. For example when compiling for
ColdFire I get:

	  LD      vmlinux
     drivers/built-in.o: In function `fec_probe':
     fec.c:(.devinit.text+0x1e0): undefined reference to `devm_clk_get'

Trivially we could conditionalize the code block that calls
devm_clk_get() in the probe routine, but that is kind of ugly.

Can you come up with a better fix?

Regards
Greg


-- 
------------------------------------------------------------------------
Greg Ungerer  --  Principal Engineer        EMAIL:     gerg at snapgear.com
SnapGear Group, McAfee                      PHONE:       +61 7 3435 2888
8 Gardner Close                             FAX:         +61 7 3217 5323
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Freescale fec.c driver breakage

[Sascha Hauer]

Hi Greg,

On Mon, Jun 04, 2012 at 02:42:28PM +1000, Greg Ungerer wrote:
> 
> Hi Sascha,
> 
> Commit f4d40de39a23f0c39cca55ac63e1175c69c3d2f7 ("net fec: do not
> depend on grouped clocks") breaks compilation of the FEC driver for
> non iMX platforms in linux-3.5-rc1. For example when compiling for
> ColdFire I get:
> 
> 	  LD      vmlinux
>     drivers/built-in.o: In function `fec_probe':
>     fec.c:(.devinit.text+0x1e0): undefined reference to `devm_clk_get'

Sorry, I forgot that this driver is used on coldfire.

> 
> Trivially we could conditionalize the code block that calls
> devm_clk_get() in the probe routine, but that is kind of ugly.

It's ugly, but the only other solution I see is that you could provide a
dummy devm_clk_get() for coldfire. Added Mark to Cc, maybe he has
another idea?

Sascha


-- 
Pengutronix e.K.                           |                             |
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Freescale fec.c driver breakage

[Mark Brown]

On Mon, Jun 04, 2012 at 10:19:37AM +0200, Sascha Hauer wrote:
> On Mon, Jun 04, 2012 at 02:42:28PM +1000, Greg Ungerer wrote:

> > Trivially we could conditionalize the code block that calls
> > devm_clk_get() in the probe routine, but that is kind of ugly.

> It's ugly, but the only other solution I see is that you could provide a
> dummy devm_clk_get() for coldfire. Added Mark to Cc, maybe he has
> another idea?

Not really, I think if the clock API is going to be usable we really
need the platforms to all be implementing it.  Part of this is getting
the stubs for !HAVE_CLK cases implemented (which doesn't seem to have
happened :/) ).  We do need to address this at the framework level,
having to put ifdefs in all the drivers is obviously awful.
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Freescale fec.c driver breakage

[Greg Ungerer]

On 04/06/12 19:16, Mark Brown wrote:
> On Mon, Jun 04, 2012 at 10:19:37AM +0200, Sascha Hauer wrote:
>> On Mon, Jun 04, 2012 at 02:42:28PM +1000, Greg Ungerer wrote:
>
>>> Trivially we could conditionalize the code block that calls
>>> devm_clk_get() in the probe routine, but that is kind of ugly.
>
>> It's ugly, but the only other solution I see is that you could provide a
>> dummy devm_clk_get() for coldfire. Added Mark to Cc, maybe he has
>> another idea?
>
> Not really, I think if the clock API is going to be usable we really
> need the platforms to all be implementing it.  Part of this is getting
> the stubs for !HAVE_CLK cases implemented (which doesn't seem to have
> happened :/) ).  We do need to address this at the framework level,
> having to put ifdefs in all the drivers is obviously awful.

Is this something you intend "fixing" then?

I don't mind putting a simplistic (but do nothing) place holder for
this function along with the other stubbed clk functions in the m68k/
coldfire code.

But more generally I am wondering does it make sense to be working
on specific platform clocks in a multi-platform/arch driver?

Regards
Greg


-- 
------------------------------------------------------------------------
Greg Ungerer  --  Principal Engineer        EMAIL:     gerg at snapgear.com
SnapGear Group, McAfee                      PHONE:       +61 7 3435 2888
8 Gardner Close                             FAX:         +61 7 3217 5323
Milton, QLD, 4064, Australia                WEB: http://www.SnapGear.com

Freescale fec.c driver breakage

[Mark Brown]

On Tue, Jun 05, 2012 at 04:55:23PM +1000, Greg Ungerer wrote:
> On 04/06/12 19:16, Mark Brown wrote:

> >Not really, I think if the clock API is going to be usable we really
> >need the platforms to all be implementing it.  Part of this is getting
> >the stubs for !HAVE_CLK cases implemented (which doesn't seem to have
> >happened :/) ).  We do need to address this at the framework level,
> >having to put ifdefs in all the drivers is obviously awful.

> Is this something you intend "fixing" then?

No, if I were going to do anything here it'd be converting everything
over to the common clock API so we didn't have to deal with this sort
of issue, it really makes the clock API unusable for generic code.

> I don't mind putting a simplistic (but do nothing) place holder for
> this function along with the other stubbed clk functions in the m68k/
> coldfire code.

> But more generally I am wondering does it make sense to be working
> on specific platform clocks in a multi-platform/arch driver?

Yes, if it's a reusable IP then it's going to have a fixed set of clocks
which go into it regardless of which platform it's hooked up to.  clkdev
provides an abstraction which can map these onto the platform, even if
you don't use the generic clk API clkdev is still very useful and will
help with a lot of these issues.
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Freescale fec.c driver breakage

[Greg Ungerer]

On 06/05/2012 07:41 PM, Mark Brown wrote:
> On Tue, Jun 05, 2012 at 04:55:23PM +1000, Greg Ungerer wrote:
>> On 04/06/12 19:16, Mark Brown wrote:
>
>>> Not really, I think if the clock API is going to be usable we really
>>> need the platforms to all be implementing it.  Part of this is getting
>>> the stubs for !HAVE_CLK cases implemented (which doesn't seem to have
>>> happened :/) ).  We do need to address this at the framework level,
>>> having to put ifdefs in all the drivers is obviously awful.
>
>> Is this something you intend "fixing" then?
>
> No, if I were going to do anything here it'd be converting everything
> over to the common clock API so we didn't have to deal with this sort
> of issue, it really makes the clock API unusable for generic code.
>
>> I don't mind putting a simplistic (but do nothing) place holder for
>> this function along with the other stubbed clk functions in the m68k/
>> coldfire code.
>
>> But more generally I am wondering does it make sense to be working
>> on specific platform clocks in a multi-platform/arch driver?
>
> Yes, if it's a reusable IP then it's going to have a fixed set of clocks
> which go into it regardless of which platform it's hooked up to.

I really don't think you can make that assumption here. Freescale have
come up with a number of weird and slightly different permutations of
this ethernet core.


> clkdev
> provides an abstraction which can map these onto the platform, even if
> you don't use the generic clk API clkdev is still very useful and will
> help with a lot of these issues.

In this specific case I don't know what the ipg or ahb clocks are on iMX
(Sascha?), but there is nothing equivalent to them in the FEC cores used
on existing ColdFire CPUs. They seem to be platform specific (iMX) more
than FEC driver specific.

Regards
Greg


------------------------------------------------------------------------
Greg Ungerer  --  Principal Engineer        EMAIL:     gerg at snapgear.com
SnapGear Group, McAfee                      PHONE:       +61 7 3435 2888
8 Gardner Close,                            FAX:         +61 7 3891 3630
Milton, QLD, 4064, Australia                WEB: http://www.SnapGear.com

Freescale fec.c driver breakage

[Mark Brown]

On Tue, Jun 05, 2012 at 10:17:02PM +1000, Greg Ungerer wrote:
> On 06/05/2012 07:41 PM, Mark Brown wrote:

> >Yes, if it's a reusable IP then it's going to have a fixed set of clocks
> >which go into it regardless of which platform it's hooked up to.

> I really don't think you can make that assumption here. Freescale have
> come up with a number of weird and slightly different permutations of
> this ethernet core.

That's just sounding like a standard "driver needs to take care of chip
revisions" thing though?

> >clkdev
> >provides an abstraction which can map these onto the platform, even if
> >you don't use the generic clk API clkdev is still very useful and will
> >help with a lot of these issues.

> In this specific case I don't know what the ipg or ahb clocks are on iMX
> (Sascha?), but there is nothing equivalent to them in the FEC cores used
> on existing ColdFire CPUs. They seem to be platform specific (iMX) more
> than FEC driver specific.

It's possible both are just always on in the ColdFire systems, at least
when Linux is running.  The AHB will be the I/O bus for the device (AHB
is a standard for interfacing between IPs) and I suspect IPG is the main
clock for the IP, both of which sound like they will always be there
even if there's no soft control of them.

FWIW I'm about to send a patch which will make devm_clk_get() available
with HAVE_CLK, though it would still be good to start looking at moving
ColdFire to the common clock infrastructure.
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Freescale fec.c driver breakage

[Greg Ungerer]

On 06/05/2012 10:24 PM, Mark Brown wrote:
> On Tue, Jun 05, 2012 at 10:17:02PM +1000, Greg Ungerer wrote:
>> On 06/05/2012 07:41 PM, Mark Brown wrote:
>
>>> Yes, if it's a reusable IP then it's going to have a fixed set of clocks
>>> which go into it regardless of which platform it's hooked up to.
>
>> I really don't think you can make that assumption here. Freescale have
>> come up with a number of weird and slightly different permutations of
>> this ethernet core.
>
> That's just sounding like a standard "driver needs to take care of chip
> revisions" thing though?
 >
>>> clkdev
>>> provides an abstraction which can map these onto the platform, even if
>>> you don't use the generic clk API clkdev is still very useful and will
>>> help with a lot of these issues.
>
>> In this specific case I don't know what the ipg or ahb clocks are on iMX
>> (Sascha?), but there is nothing equivalent to them in the FEC cores used
>> on existing ColdFire CPUs. They seem to be platform specific (iMX) more
>> than FEC driver specific.
>
> It's possible both are just always on in the ColdFire systems, at least
> when Linux is running.  The AHB will be the I/O bus for the device (AHB
> is a standard for interfacing between IPs) and I suspect IPG is the main
> clock for the IP, both of which sound like they will always be there
> even if there's no soft control of them.

I am pretty sure AHB was bolted on later. This FEC core has progressed
from very old Motorola PowerPC platforms to ColdFire/M68k to ARM, over
something coming close to a 20 year period. In the earlier uses of it
there is quite a few differences (including some quite odd register
layout differences).

There may be other things that are somewhat like an ahb clock and ipg
clock, but really these are things that have come along later with a
specific platform implementation.


> FWIW I'm about to send a patch which will make devm_clk_get() available
> with HAVE_CLK, though it would still be good to start looking at moving
> ColdFire to the common clock infrastructure.

Sure, agreed.

Regards
Greg


------------------------------------------------------------------------
Greg Ungerer  --  Principal Engineer        EMAIL:     gerg at snapgear.com
SnapGear Group, McAfee                      PHONE:       +61 7 3435 2888
8 Gardner Close,                            FAX:         +61 7 3891 3630
Milton, QLD, 4064, Australia                WEB: http://www.SnapGear.com

Freescale fec.c driver breakage

[Mark Brown]

On Tue, Jun 05, 2012 at 10:36:30PM +1000, Greg Ungerer wrote:

> I am pretty sure AHB was bolted on later. This FEC core has progressed
> from very old Motorola PowerPC platforms to ColdFire/M68k to ARM, over
> something coming close to a 20 year period. In the earlier uses of it
> there is quite a few differences (including some quite odd register
> layout differences).

> There may be other things that are somewhat like an ahb clock and ipg
> clock, but really these are things that have come along later with a
> specific platform implementation.

For AHB that sounds plausible, but for the IPG clock (assuming I've
identified the function correctly) I've got a very hard time believing
that the IP ever didn't need a clock - my understanding is that it's the
master clock for the IP ("IP gate").
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Freescale fec.c driver breakage

[Sascha Hauer]

On Tue, Jun 05, 2012 at 10:17:02PM +1000, Greg Ungerer wrote:
> 
> >clkdev
> >provides an abstraction which can map these onto the platform, even if
> >you don't use the generic clk API clkdev is still very useful and will
> >help with a lot of these issues.
> 
> In this specific case I don't know what the ipg or ahb clocks are on iMX
> (Sascha?), but there is nothing equivalent to them in the FEC cores used
> on existing ColdFire CPUs. They seem to be platform specific (iMX) more
> than FEC driver specific.

I am sure the Coldfire FEC also needs clocks to work. Just like Mark
said, they may be not software controllable. The names 'ipg' and 'ahb'
may be i.MX specific though.

Sascha


-- 
Pengutronix e.K.                           |                             |
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Freescale fec.c driver breakage

[Greg Ungerer]

On 06/05/2012 10:48 PM, Sascha Hauer wrote:
> On Tue, Jun 05, 2012 at 10:17:02PM +1000, Greg Ungerer wrote:
>>
>>> clkdev
>>> provides an abstraction which can map these onto the platform, even if
>>> you don't use the generic clk API clkdev is still very useful and will
>>> help with a lot of these issues.
>>
>> In this specific case I don't know what the ipg or ahb clocks are on iMX
>> (Sascha?), but there is nothing equivalent to them in the FEC cores used
>> on existing ColdFire CPUs. They seem to be platform specific (iMX) more
>> than FEC driver specific.
>
> I am sure the Coldfire FEC also needs clocks to work. Just like Mark
> said, they may be not software controllable. The names 'ipg' and 'ahb'
> may be i.MX specific though.

Well, yeah, of course there are clocks involved. But you pretty much
hit the point here. 'ipg' and 'ahb' here are platform specific.

Regards
Greg


------------------------------------------------------------------------
Greg Ungerer  --  Principal Engineer        EMAIL:     gerg at snapgear.com
SnapGear Group, McAfee                      PHONE:       +61 7 3435 2888
8 Gardner Close,                            FAX:         +61 7 3891 3630
Milton, QLD, 4064, Australia                WEB: http://www.SnapGear.com

Freescale fec.c driver breakage

[Mark Brown]

On Tue, Jun 05, 2012 at 11:24:29PM +1000, Greg Ungerer wrote:

> Well, yeah, of course there are clocks involved. But you pretty much
> hit the point here. 'ipg' and 'ahb' here are platform specific.

What should be happening for that is that the driver requests with some
generic name which is referenced to the IP (unfortunately these are
usually not documented for the public...) and then clkdev or some
platform specific code is used to map the names onto the underlying
clocks.

If 'ahb' isn't suitable how about 'bus', and for 'ipg' how about 'mclk'
or something?
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Freescale fec.c driver breakage

[Steven King]

On Tuesday 05 June 2012 6:41:16 am Mark Brown wrote:
> On Tue, Jun 05, 2012 at 11:24:29PM +1000, Greg Ungerer wrote:
> > Well, yeah, of course there are clocks involved. But you pretty much
> > hit the point here. 'ipg' and 'ahb' here are platform specific.
>
> What should be happening for that is that the driver requests with some
> generic name which is referenced to the IP (unfortunately these are
> usually not documented for the public...) and then clkdev or some
> platform specific code is used to map the names onto the underlying
> clocks.
>
> If 'ahb' isn't suitable how about 'bus', and for 'ipg' how about 'mclk'
> or something?

Some of the newer Coldfire parts such as the m54455/m5441x do have software 
controllable clocks; but they keep it simple with one clock per fec, and 
names in the documentation like 'fec0, fec1' for the m54455 
and 'macnet0,macnet1' for the m5441x. 

Freescale fec.c driver breakage

[Greg Ungerer]

On 06/06/12 00:35, Steven King wrote:
> On Tuesday 05 June 2012 6:41:16 am Mark Brown wrote:
>> On Tue, Jun 05, 2012 at 11:24:29PM +1000, Greg Ungerer wrote:
>>> Well, yeah, of course there are clocks involved. But you pretty much
>>> hit the point here. 'ipg' and 'ahb' here are platform specific.
>>
>> What should be happening for that is that the driver requests with some
>> generic name which is referenced to the IP (unfortunately these are
>> usually not documented for the public...) and then clkdev or some
>> platform specific code is used to map the names onto the underlying
>> clocks.
>>
>> If 'ahb' isn't suitable how about 'bus', and for 'ipg' how about 'mclk'
>> or something?
>
> Some of the newer Coldfire parts such as the m54455/m5441x do have software
> controllable clocks; but they keep it simple with one clock per fec, and
> names in the documentation like 'fec0, fec1' for the m54455
> and 'macnet0,macnet1' for the m5441x.

Most of the older ones don't. Most of the older parts that have a FEC
core have a single clock-in for the chip, possibly a PLL and often a
fixed divisor for distribuion to all on-chip peripherals. I have seen it
named various names, 'bclko', 'mclk', "fsys/2", nothing seems consistent.

I think very generic namse might be the best solution here.

Regards
Greg


------------------------------------------------------------------------
Greg Ungerer  --  Principal Engineer        EMAIL:     gerg at snapgear.com
SnapGear Group, McAfee                      PHONE:       +61 7 3435 2888
8 Gardner Close                             FAX:         +61 7 3217 5323
Milton, QLD, 4064, Australia                WEB: http://www.SnapGear.com

Freescale fec.c driver breakage

[Mark Brown]

On Wed, Jun 06, 2012 at 05:41:08PM +1000, Greg Ungerer wrote:

> Most of the older ones don't. Most of the older parts that have a FEC
> core have a single clock-in for the chip, possibly a PLL and often a
> fixed divisor for distribuion to all on-chip peripherals. I have seen it
> named various names, 'bclko', 'mclk', "fsys/2", nothing seems consistent.

> I think very generic namse might be the best solution here.

Bear in mind that the IP level names shouldn't need to correspond to the
names used in the overall system integration.
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Freescale fec.c driver breakage

[Sascha Hauer]

On Tue, Jun 05, 2012 at 11:24:29PM +1000, Greg Ungerer wrote:
> On 06/05/2012 10:48 PM, Sascha Hauer wrote:
> >On Tue, Jun 05, 2012 at 10:17:02PM +1000, Greg Ungerer wrote:
> >>
> >>>clkdev
> >>>provides an abstraction which can map these onto the platform, even if
> >>>you don't use the generic clk API clkdev is still very useful and will
> >>>help with a lot of these issues.
> >>
> >>In this specific case I don't know what the ipg or ahb clocks are on iMX
> >>(Sascha?), but there is nothing equivalent to them in the FEC cores used
> >>on existing ColdFire CPUs. They seem to be platform specific (iMX) more
> >>than FEC driver specific.
> >
> >I am sure the Coldfire FEC also needs clocks to work. Just like Mark
> >said, they may be not software controllable. The names 'ipg' and 'ahb'
> >may be i.MX specific though.
> 
> Well, yeah, of course there are clocks involved. But you pretty much
> hit the point here. 'ipg' and 'ahb' here are platform specific.

Are there any FEC specific names? If yes, we could use these instead,
otherwise if we have to make up names ourselves I think 'ipg' and 'ahb'
are fine.

Sascha

-- 
Pengutronix e.K.                           |                             |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |
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Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |