Backporting MTU3a counter driver to linux-5.10.y-cip

Backporting MTU3a counter driver to linux-5.10.y-cip

[Biju Das]

Hi All,

RZ/G2L MTU3a counter driver support is added to 6.4 mainline kernel [1].

Counter framework restructure happened from 5.15 along with that
all vendor specific driver code is also updated[2] and [3]

Other than that lot of sysfs entries added after 5.10 see [4]

Q1) Do you have any suggestion how to support counter driver in 5.10.y-cip?


[1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?h=v6.4-rc2&id=0be8907359df4c62319f5cb2c6981ff0d9ebf35a

[2] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/drivers/counter?h=v6.4-rc2&id=aaec1a0f76ec25f46bbb17b81487c4b0e1c318c5

[3] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/drivers/counter?h=v6.4-rc2&id=b6c50affda5957a3629b149a91c7f6688ffce7f7

[4] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/log/Documentation/ABI/testing/sysfs-bus-counter?h=v6.4-rc2


Cheers,
Biju

RE: Backporting MTU3a counter driver to linux-5.10.y-cip

[Biju Das]

MTU3a Counter driver based on IIO framework is available in BSP[1].

Is it acceptable to add MTU3a Counter driver support using IIO framework for 
5.10.y cip kernel?

[1] https://github.com/renesas-rz/rz_linux-cip/blob/rz-5.10-cip22/drivers/clocksource/renesas-mtu3.c

Cheers,
Biju

> -----Original Message-----
> From: Biju Das
> Sent: Monday, May 15, 2023 8:27 AM
> To: cip-dev@lists.cip-project.org
> Subject: Backporting MTU3a counter driver to linux-5.10.y-cip
> 
> Hi All,
> 
> RZ/G2L MTU3a counter driver support is added to 6.4 mainline kernel [1].
> 
> Counter framework restructure happened from 5.15 along with that all
> vendor specific driver code is also updated[2] and [3]
> 
> Other than that lot of sysfs entries added after 5.10 see [4]
> 
> Q1) Do you have any suggestion how to support counter driver in 5.10.y-
> cip?
> 
> 
> [1]
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commi
> t/?h=v6.4-rc2&id=0be8907359df4c62319f5cb2c6981ff0d9ebf35a
> 
> [2]
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commi
> t/drivers/counter?h=v6.4-rc2&id=aaec1a0f76ec25f46bbb17b81487c4b0e1c318c5
> 
> [3]
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commi
> t/drivers/counter?h=v6.4-rc2&id=b6c50affda5957a3629b149a91c7f6688ffce7f7
> 
> [4]
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/log/D
> ocumentation/ABI/testing/sysfs-bus-counter?h=v6.4-rc2
> 
> 
> Cheers,
> Biju

Re: [cip-dev] Backporting MTU3a counter driver to linux-5.10.y-cip

[Pavel Machek]

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Hi!

> > Hi All,
> > 
> > RZ/G2L MTU3a counter driver support is added to 6.4 mainline kernel [1].
> > 
> > Counter framework restructure happened from 5.15 along with that all
> > vendor specific driver code is also updated[2] and [3]
> > 
> > Other than that lot of sysfs entries added after 5.10 see [4]
> > 
> > Q1) Do you have any suggestion how to support counter driver in 5.10.y-
> > cip?

Fun... Let me take a look. It would have been good to bring it up on
the IRC meeting, but I forgot.

> MTU3a Counter driver based on IIO framework is available in BSP[1].
> 
> Is it acceptable to add MTU3a Counter driver support using IIO framework for 
> 5.10.y cip kernel?

So AFAICT there are three possibilities:

1) Say we can't / don't want to merge the counter driver to 5.10-cip
as it is too intrusive. Would it be enough for you/your users to have
in 6.1-cip?

2) Update counter subsystem in 5.10-cip with patches from 5.15, then
merge the driver from 6.4.

3) Merge iio driver from rz-5.10-cip22 as is.

Are there other people using counter subsystem in 5.10-cip? If so, 2)
may interfere with their usage. 3) is a bit sad, as it presents
non-mainline interface to userland, and the userland code will need to
be updated. Plus 3) also violates our rules, as it is not mainline
backport.

Best regards,
								Pavel

> [1] https://github.com/renesas-rz/rz_linux-cip/blob/rz-5.10-cip22/drivers/clocksource/renesas-mtu3.c

> > [1]
> > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commi
> > t/?h=v6.4-rc2&id=0be8907359df4c62319f5cb2c6981ff0d9ebf35a
> > 
> > [2]
> > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commi
> > t/drivers/counter?h=v6.4-rc2&id=aaec1a0f76ec25f46bbb17b81487c4b0e1c318c5
> > 
> > [3]
> > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commi
> > t/drivers/counter?h=v6.4-rc2&id=b6c50affda5957a3629b149a91c7f6688ffce7f7
> > 
> > [4]
> > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/log/D
> > ocumentation/ABI/testing/sysfs-bus-counter?h=v6.4-rc2

-- 
DENX Software Engineering GmbH,        Managing Director: Erika Unter
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany

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RE: [cip-dev] Backporting MTU3a counter driver to linux-5.10.y-cip

[Biju Das]

Hi Pavel,

Thanks for the feedback.

> Subject: Re: [cip-dev] Backporting MTU3a counter driver to linux-5.10.y-
> cip
> 
> Hi!
> 
> > > Hi All,
> > >
> > > RZ/G2L MTU3a counter driver support is added to 6.4 mainline kernel
> [1].
> > >
> > > Counter framework restructure happened from 5.15 along with that all
> > > vendor specific driver code is also updated[2] and [3]
> > >
> > > Other than that lot of sysfs entries added after 5.10 see [4]
> > >
> > > Q1) Do you have any suggestion how to support counter driver in
> > > 5.10.y- cip?
> 
> Fun... Let me take a look. It would have been good to bring it up on the
> IRC meeting, but I forgot.
> 
> > MTU3a Counter driver based on IIO framework is available in BSP[1].
> >
> > Is it acceptable to add MTU3a Counter driver support using IIO
> > framework for 5.10.y cip kernel?
> 
> So AFAICT there are three possibilities:
> 
> 1) Say we can't / don't want to merge the counter driver to 5.10-cip as
> it is too intrusive. Would it be enough for you/your users to have in
> 6.1-cip?

Yes, We have a plan to backport this driver to 6.1-cip.

> 
> 2) Update counter subsystem in 5.10-cip with patches from 5.15, then
> merge the driver from 6.4.
> 
> 3) Merge iio driver from rz-5.10-cip22 as is.
> 
> Are there other people using counter subsystem in 5.10-cip? 

Yes, other vendors are using counter subsystem.

If so, 2)
> may interfere with their usage. 

Yes, it will interfere their usage as SYSFS entries going to change.

3) is a bit sad, as it presents non-
> mainline interface to userland, and the userland code will need to be
> updated. Plus 3) also violates our rules, as it is not mainline
> backport.

So basically 2 and 3 ruled out. The only option left out is 1??

Cheers,
Biju

Re: [cip-dev] Backporting MTU3a counter driver to linux-5.10.y-cip

[Pavel Machek]

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Hi!

> > 2) Update counter subsystem in 5.10-cip with patches from 5.15, then
> > merge the driver from 6.4.

> So basically 2 and 3 ruled out. The only option left out is 1??

So we discussed options on todays meeting on IRC (you may want to
review the log)... and if you are willing to do the work, we are
willing to consider option 2.

That does not mean we are willing to do updates on other subsystems --
this should really be an exception -- but it seems counter subsystem
is simple enough and you may be the only user in -cip.

(Of course, the patches need to be reasonable and reviewable etc).

Best regards,
     	       	       	     	      	   	       	        Pavel
-- 
DENX Software Engineering GmbH,        Managing Director: Erika Unter
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany

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RE: [cip-dev] Backporting MTU3a counter driver to linux-5.10.y-cip

[Biju Das]

Hi Pavel,

Thanks for the feedback.

> -----Original Message-----
> From: cip-dev@lists.cip-project.org <cip-dev@lists.cip-project.org> On
> Behalf Of Pavel Machek via lists.cip-project.org
> Sent: Thursday, June 1, 2023 1:50 PM
> To: cip-dev@lists.cip-project.org
> Subject: Re: [cip-dev] Backporting MTU3a counter driver to linux-5.10.y-
> cip
> 
> Hi!
> 
> > > 2) Update counter subsystem in 5.10-cip with patches from 5.15, then
> > > merge the driver from 6.4.
> 
> > So basically 2 and 3 ruled out. The only option left out is 1??
> 
> So we discussed options on todays meeting on IRC (you may want to review
> the log)... and if you are willing to do the work, we are willing to
> consider option 2.
> 
> That does not mean we are willing to do updates on other subsystems --
> this should really be an exception -- but it seems counter subsystem is
> simple enough and you may be the only user in -cip.
> 
> (Of course, the patches need to be reasonable and reviewable etc).

OK will revisit and send some patches if it is in reasonable and reviewable state
for 5.10.y-cip.

By the way we have backported counter driver to 6.1 without any issues
We will be sending counter driver patches for 6.1 soon.

Cheers,
Biju