linux-kernel - RE: [PATCH v6 01/11] x86/tsc: Add base clock properties in clocksource structure

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Date: Tue, 16 Apr 2024 10:10:24 +0000
From: "D, Lakshmi Sowjanya" <lakshmi.sowjanya.d@...el.com>
To: Thomas Gleixner <tglx@...utronix.de>, "jstultz@...gle.com"
	<jstultz@...gle.com>, "giometti@...eenne.com" <giometti@...eenne.com>,
	"corbet@....net" <corbet@....net>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>
CC: "x86@...nel.org" <x86@...nel.org>, "netdev@...r.kernel.org"
	<netdev@...r.kernel.org>, "linux-doc@...r.kernel.org"
	<linux-doc@...r.kernel.org>, "intel-wired-lan@...ts.osuosl.org"
	<intel-wired-lan@...ts.osuosl.org>, "andriy.shevchenko@...ux.intel.com"
	<andriy.shevchenko@...ux.intel.com>, "Dong, Eddie" <eddie.dong@...el.com>,
	"Hall, Christopher S" <christopher.s.hall@...el.com>, "Brandeburg, Jesse"
	<jesse.brandeburg@...el.com>, "davem@...emloft.net" <davem@...emloft.net>,
	"alexandre.torgue@...s.st.com" <alexandre.torgue@...s.st.com>,
	"joabreu@...opsys.com" <joabreu@...opsys.com>, "mcoquelin.stm32@...il.com"
	<mcoquelin.stm32@...il.com>, "perex@...ex.cz" <perex@...ex.cz>,
	"linux-sound@...r.kernel.org" <linux-sound@...r.kernel.org>, "Nguyen, Anthony
 L" <anthony.l.nguyen@...el.com>, "peter.hilber@...nsynergy.com"
	<peter.hilber@...nsynergy.com>, "N, Pandith" <pandith.n@...el.com>, "Mohan,
 Subramanian" <subramanian.mohan@...el.com>, "T R, Thejesh Reddy"
	<thejesh.reddy.t.r@...el.com>
Subject: RE: [PATCH v6 01/11] x86/tsc: Add base clock properties in
 clocksource structure



> -----Original Message-----
> From: Thomas Gleixner <tglx@...utronix.de>
> Sent: Thursday, April 11, 2024 2:51 AM
> To: D, Lakshmi Sowjanya <lakshmi.sowjanya.d@...el.com>;
> jstultz@...gle.com; giometti@...eenne.com; corbet@....net; linux-
> kernel@...r.kernel.org
> Cc: x86@...nel.org; netdev@...r.kernel.org; linux-doc@...r.kernel.org; intel-
> wired-lan@...ts.osuosl.org; andriy.shevchenko@...ux.intel.com; Dong, Eddie
> <eddie.dong@...el.com>; Hall, Christopher S <christopher.s.hall@...el.com>;
> Brandeburg, Jesse <jesse.brandeburg@...el.com>; davem@...emloft.net;
> alexandre.torgue@...s.st.com; joabreu@...opsys.com;
> mcoquelin.stm32@...il.com; perex@...ex.cz; linux-sound@...r.kernel.org;
> Nguyen, Anthony L <anthony.l.nguyen@...el.com>;
> peter.hilber@...nsynergy.com; N, Pandith <pandith.n@...el.com>; Mohan,
> Subramanian <subramanian.mohan@...el.com>; T R, Thejesh Reddy
> <thejesh.reddy.t.r@...el.com>; D, Lakshmi Sowjanya
> <lakshmi.sowjanya.d@...el.com>
> Subject: Re: [PATCH v6 01/11] x86/tsc: Add base clock properties in clocksource
> structure
> 
> On Wed, Apr 10 2024 at 17:18, lakshmi.sowjanya.d@...el.com wrote:
> > From: Lakshmi Sowjanya D <lakshmi.sowjanya.d@...el.com>
> >
> > Add base clock hardware abstraction in clocksource structure.
> >
> > Add clocksource ID for x86 ART(Always Running Timer). The newly added
> > clocksource ID and conversion parameters are used to convert time in a
> > clocksource domain to base clock and vice versa.
> >
> > Convert the base clock to the system clock using convert_base_to_cs()
> > in get_device_system_crosststamp().
> 
> In https://lore.kernel.org/all/875xxhi1ty.ffs@tglx I asked you to provide a
> change log which explains the WHY and not the WHAT. The new change log still
> fails to explain WHY this change is needed and which problem it is trying to
> solve.

Rephrased the commit message to:
" Add base clock hardware abstraction in clocksource structure.

The core code has a mechanism to convert the ART base clock to
the corresponding tsc value. 
Provide the generic functionality in convert_base_to_cs() to convert
base clock timestamps to system clocksource without requiring
architecture specific parameters.

Add the infrastructure in get_device_system_crosststamp()."

> 
> I further asked you to do:
> 
>     1) Add the clocksource_base struct and provide the infrastructure in
>        get_device_system_crosststamp()
> 
>     2) Make TSC/ART use it
> 
> But this still does #1 and #2 in one go.
> 
> If you don't understand my review comments, then please ask. If you disagree
> with them then please tell me and argue with me.
> 
> Just ignoring them is not an option.

Sorry Thomas, that was a mis-understanding. We had split only realtime as separate patch.
We will split the first patch as suggested. 
	1. Timekeeping part(convert_base_to_cs() and infrastructure in get_device_system_crosststamp())
	2. x86(TSC/ART values update into the structure)

Thanks,
Sowjanya

> 
> Thanks,
> 
>         tglx