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From: Richard Zhao <linuxzsc@gmail.com>
To: linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 0/4] Add a generic struct clk
Date: Wed, 25 May 2011 02:08:51 +0000	[thread overview]
Message-ID: <20110525020850.GA2173@b20223-02.ap.freescale.net> (raw)
In-Reply-To: <BANLkTimY1cxqaPG1T=_xKPustXR1GSmUKQ@mail.gmail.com>

On Tue, May 24, 2011 at 10:52:53AM -0700, Colin Cross wrote:
> On Tue, May 24, 2011 at 10:22 AM, Richard Zhao <linuxzsc@gmail.com> wrote:
> > On Mon, May 23, 2011 at 04:12:24PM -0700, Colin Cross wrote:
> >> On Fri, May 20, 2011 at 12:27 AM, Jeremy Kerr <jeremy.kerr@canonical.com> wrote:
> >> > [This series was originally titled 'Add a common struct clk', but
> >> > the goals have changed since that first set of patches. We're now aiming
> >> > for a more complete generic clock infrastructure, rather than just
> >> > abstracting struct clk]
> >> >
> >> > [This series still needs work, see the TODO section below]
> >> >
> >> > [Totally RFC at the moment]
> >> >
> >> > Hi all,
> >> >
> >> > These patches are an attempt to allow platforms to share clock code. At
> >> > present, the definitions of 'struct clk' are local to platform code,
> >> > which makes allocating and initialising cross-platform clock sources
> >> > difficult, and makes it impossible to compile a single image containing
> >> > support for two ARM platforms with different struct clks.
> >> >
> >> > The three patches are for the architecture-independent kernel code,
> >> > introducing the common clk infrastructure. The changelog for the first
> >> > patch includes details about the new clock definitions.
> >> >
> >> > The second patch implements clk_set_rate, and in doing so adds
> >> > functionality to walk the clock tree in both directions.
> >> >
> >> > clk_set_parent is left unimplemented, see TODO below for why.
> >> >
> >> > The third and fourth patches provide some basic clocks (fixed-rate and
> >> > gated), mostly to serve as an example of the hardware implementation.
> >> > I'm intending to later provide similar base clocks for mux and divider
> >> > hardware clocks.
> >> >
> >> > Many thanks to the following for their input:
> >> >  * Benjamin Herrenschmidt <benh@kernel.crashing.org>
> >> >  * Thomas Gleixner <tglx@linutronix.de>
> >> >  * Ben Dooks <ben-linux@fluff.org>
> >> >  * Baruch Siach <baruch@tkos.co.il>
> >> >  * Russell King <linux@arm.linux.org.uk>
> >> >  * Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
> >> >  * Lorenzo Pieralisi <Lorenzo.Pieralisi@arm.com>
> >> >  * Vincent Guittot <vincent.guittot@linaro.org>
> >> >  * Sascha Hauer <s.hauer@pengutronix.de>
> >> >  * Ryan Mallon <ryan@bluewatersys.com>
> >> >  * Colin Cross <ccross@google.com>
> >> >  * Jassi Brar <jassisinghbrar@gmail.com>
> >> >  * Saravana Kannan <skannan@codeaurora.org>
> >>
> >> I have a similar set of patches I was working on that handles a little
> >> more of the common code than these.  I can post them if you want, but
> >> for now I'll just point out where I had different ideas, and not muddy
> >> the waters with conflicting patches.
> >>
> >> > TODO:
> >> >
> >> >  * Need to figure out the locking around clk_set_parent. Changing the in-kernel
> >> >   clock topology requires acquiring both the mutex (to prevent against races
> >> >   with clk_prepare, which may propagate to the parent clock) and the spinlock
> >> >   (to prevent the same race with clk_enable).
> >> >
> >> >   However, we should also be changing the hardware clock topology in sync with
> >> >   the in-kernel clock topology, which would imply that both locks *also* need
> >> >   to be held while updating the parent in the hardware (ie, in
> >> >   clk_hw_ops->set_parent) too.  However, I believe some platform clock
> >> >   implementations may require this callback to be able to sleep. Comments?
> >>
> >> This sequence is the best I could come up with without adding a
> >> temporary 2nd parent:
> >> 1. lock prepare mutex
> > Maybe tell child clocks "I'm going to change clock rate, please stop work if needed"
> >> 2. call prepare on the new parent if prepare_count > 0
> >> 3. lock the enable spinlock
> >> 4. call enable on the new parent if enable_count > 0
> >> 5. change the parent pointer to the new parent
> >> 6. unlock the spinlock
> >> 7. call the set_parent callback
> > Why do it need to sleep if it only set some hw registers?
> 
> Most implementations don't, and I would be fine with saying
> clk_set_parent sleeps, but the set_parent op does not, but that
> prevents clock chips on sleeping busses like i2c.
So it worth to involve a flag here, which says hw_ops may sleep. At least for
on-SoC clocks, we don't need to take risk.
> 
> >> 8. lock the enable spinlock
> >> 9. call disable on the old parent iff you called enable on the new
> >> parent (enable_count may have changed)
> >> 10. unlock the enable spinlock
> >> 11. call unprepare on the old parent if prepare_count
> > propagate rate here and also tell child clocks "rate changed already, change your
> > parameters and go on to work".
> 
> Yes, propagate rate is needed.
> 
> >> 12. unlock prepare mutex
> >>
> >> The only possible problem I see is that if a clock starts disabled at
> >> step 1., and clk_enable is called on it between steps 6 and 7,
> >> clk_enable will return having enabled the new parent, but the clock is
> >> still running off the old parent.  As soon as the clock gets switched
> >> to the new parent, the clock will be properly enabled.  I don't see
> >> this as a huge problem - calling clk_set_parent on a clock while it is
> >> enabled may not even work without causing glitches on some platforms.
> > some do be glitch free, especially for cpu clock parents.
> >>
> >> I guess the only way around it would be to store a temporary
> >> "new_parent" pointer between steps 5 and 9, and have
> >> clk_enable/disable operate on both the current parent and the new
> >> parent.  They would also need to refcount the extra enables separately
> >> to undo on the old parent.
> >>
> >> >  * tglx and I have been discussing different ways of passing clock information
> >> >   to the clock hardware implementation. I'm proposing providing a base 'struct
> >> >   clk_hw', which implementations subclass by wrapping in their own structure
> >> >   (or one of a set of simple 'library' structures, like clk_hw_mux or
> >> >   clk_hw_gate).  The clk_hw base is passed as the first argument to all
> >> >   clk_hw_ops callbacks.
> >> >
> >> >   tglx's plan is to create a separate struct clk_hwdata, which contains a
> >> >   union of base data structures for common clocks: div, mux, gate, etc. The
> >> >   ops callbacks are passed a clk_hw, plus a clk_hwdata, and most of the base
> >> >   hwdata fields are handled within the core clock code. This means less
> >> >   encapsulation of clock implementation logic, but more coverage of
> >> >   clock basics through the core code.
> >>
> >> I don't think they should be a union, I think there should be 3
> >> separate private datas, and three sets of clock ops, for the three
> >> different types of clock blocks: rate changers (dividers and plls),
> >> muxes, and gates.  These blocks are very often combined - a device
> >> clock often has a mux and a divider, and clk_set_parent and
> >> clk_set_rate on the same struct clk both need to work.
> >>
> >> >   tglx, could you send some details about your approach? I'm aiming to refine
> >> >   this series with the good bits from each technique.
> >> >
> >> >  * The clock registration code probably needs work. This is the domain
> >> >   of the platform/board maintainers, any wishes here?
> > When clock init, data in struct clk may not be synced with hw registers. After
> > enabled minimal needed clk (cpu, core bus etc), we need sync the whole tree,
> > disable zero enable_count clocks, set correct .rate ... . The sync function
> > is also common code, right? but not have to be called all times I think.
> 
> I believe each clock is synced with its hardware during clk_register
> by calling the recalc_rate and get_parent callbacks.
so how to sync gate bits? Let subarch to set registers directly or clk_enable and
clk_disable to make sure clk is disabled? Neither way is good I think.

Thanks
Richard
> 
> > Thanks
> > Richard
> >> >
> >> > Cheers,
> >> >
> >> >
> >> > Jeremy
> >> >
> >> > --
> >> >
> >> > ---
> >> > Jeremy Kerr (4):
> >> >      clk: Add a generic clock infrastructure
> >> >      clk: Implement clk_set_rate
> >> >      clk: Add fixed-rate clock
> >> >      clk: Add simple gated clock
> >> >
> >> > --
> >> > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> >> > the body of a message to majordomo@vger.kernel.org
> >> > More majordomo info at  http://vger.kernel.org/majordomo-info.html
> >> > Please read the FAQ at  http://www.tux.org/lkml/
> >> >
> >>
> >> _______________________________________________
> >> linux-arm-kernel mailing list
> >> linux-arm-kernel@lists.infradead.org
> >> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
> >
> 
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
> 

WARNING: multiple messages have this Message-ID
From: Richard Zhao <linuxzsc@gmail.com>
To: Colin Cross <ccross@google.com>
Cc: Jeremy Kerr <jeremy.kerr@canonical.com>,
	linux-sh@vger.kernel.org, Thomas Gleixner <tglx@linutronix.de>,
	"linux-arm-kernel@lists.infradead.org" 
	<linux-arm-kernel@lists.infradead.org>,
	lkml <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 0/4] Add a generic struct clk
Date: Wed, 25 May 2011 10:08:51 +0800	[thread overview]
Message-ID: <20110525020850.GA2173@b20223-02.ap.freescale.net> (raw)
In-Reply-To: <BANLkTimY1cxqaPG1T=_xKPustXR1GSmUKQ@mail.gmail.com>

On Tue, May 24, 2011 at 10:52:53AM -0700, Colin Cross wrote:
> On Tue, May 24, 2011 at 10:22 AM, Richard Zhao <linuxzsc@gmail.com> wrote:
> > On Mon, May 23, 2011 at 04:12:24PM -0700, Colin Cross wrote:
> >> On Fri, May 20, 2011 at 12:27 AM, Jeremy Kerr <jeremy.kerr@canonical.com> wrote:
> >> > [This series was originally titled 'Add a common struct clk', but
> >> > the goals have changed since that first set of patches. We're now aiming
> >> > for a more complete generic clock infrastructure, rather than just
> >> > abstracting struct clk]
> >> >
> >> > [This series still needs work, see the TODO section below]
> >> >
> >> > [Totally RFC at the moment]
> >> >
> >> > Hi all,
> >> >
> >> > These patches are an attempt to allow platforms to share clock code. At
> >> > present, the definitions of 'struct clk' are local to platform code,
> >> > which makes allocating and initialising cross-platform clock sources
> >> > difficult, and makes it impossible to compile a single image containing
> >> > support for two ARM platforms with different struct clks.
> >> >
> >> > The three patches are for the architecture-independent kernel code,
> >> > introducing the common clk infrastructure. The changelog for the first
> >> > patch includes details about the new clock definitions.
> >> >
> >> > The second patch implements clk_set_rate, and in doing so adds
> >> > functionality to walk the clock tree in both directions.
> >> >
> >> > clk_set_parent is left unimplemented, see TODO below for why.
> >> >
> >> > The third and fourth patches provide some basic clocks (fixed-rate and
> >> > gated), mostly to serve as an example of the hardware implementation.
> >> > I'm intending to later provide similar base clocks for mux and divider
> >> > hardware clocks.
> >> >
> >> > Many thanks to the following for their input:
> >> >  * Benjamin Herrenschmidt <benh@kernel.crashing.org>
> >> >  * Thomas Gleixner <tglx@linutronix.de>
> >> >  * Ben Dooks <ben-linux@fluff.org>
> >> >  * Baruch Siach <baruch@tkos.co.il>
> >> >  * Russell King <linux@arm.linux.org.uk>
> >> >  * Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
> >> >  * Lorenzo Pieralisi <Lorenzo.Pieralisi@arm.com>
> >> >  * Vincent Guittot <vincent.guittot@linaro.org>
> >> >  * Sascha Hauer <s.hauer@pengutronix.de>
> >> >  * Ryan Mallon <ryan@bluewatersys.com>
> >> >  * Colin Cross <ccross@google.com>
> >> >  * Jassi Brar <jassisinghbrar@gmail.com>
> >> >  * Saravana Kannan <skannan@codeaurora.org>
> >>
> >> I have a similar set of patches I was working on that handles a little
> >> more of the common code than these.  I can post them if you want, but
> >> for now I'll just point out where I had different ideas, and not muddy
> >> the waters with conflicting patches.
> >>
> >> > TODO:
> >> >
> >> >  * Need to figure out the locking around clk_set_parent. Changing the in-kernel
> >> >   clock topology requires acquiring both the mutex (to prevent against races
> >> >   with clk_prepare, which may propagate to the parent clock) and the spinlock
> >> >   (to prevent the same race with clk_enable).
> >> >
> >> >   However, we should also be changing the hardware clock topology in sync with
> >> >   the in-kernel clock topology, which would imply that both locks *also* need
> >> >   to be held while updating the parent in the hardware (ie, in
> >> >   clk_hw_ops->set_parent) too.  However, I believe some platform clock
> >> >   implementations may require this callback to be able to sleep. Comments?
> >>
> >> This sequence is the best I could come up with without adding a
> >> temporary 2nd parent:
> >> 1. lock prepare mutex
> > Maybe tell child clocks "I'm going to change clock rate, please stop work if needed"
> >> 2. call prepare on the new parent if prepare_count > 0
> >> 3. lock the enable spinlock
> >> 4. call enable on the new parent if enable_count > 0
> >> 5. change the parent pointer to the new parent
> >> 6. unlock the spinlock
> >> 7. call the set_parent callback
> > Why do it need to sleep if it only set some hw registers?
> 
> Most implementations don't, and I would be fine with saying
> clk_set_parent sleeps, but the set_parent op does not, but that
> prevents clock chips on sleeping busses like i2c.
So it worth to involve a flag here, which says hw_ops may sleep. At least for
on-SoC clocks, we don't need to take risk.
> 
> >> 8. lock the enable spinlock
> >> 9. call disable on the old parent iff you called enable on the new
> >> parent (enable_count may have changed)
> >> 10. unlock the enable spinlock
> >> 11. call unprepare on the old parent if prepare_count
> > propagate rate here and also tell child clocks "rate changed already, change your
> > parameters and go on to work".
> 
> Yes, propagate rate is needed.
> 
> >> 12. unlock prepare mutex
> >>
> >> The only possible problem I see is that if a clock starts disabled at
> >> step 1., and clk_enable is called on it between steps 6 and 7,
> >> clk_enable will return having enabled the new parent, but the clock is
> >> still running off the old parent.  As soon as the clock gets switched
> >> to the new parent, the clock will be properly enabled.  I don't see
> >> this as a huge problem - calling clk_set_parent on a clock while it is
> >> enabled may not even work without causing glitches on some platforms.
> > some do be glitch free, especially for cpu clock parents.
> >>
> >> I guess the only way around it would be to store a temporary
> >> "new_parent" pointer between steps 5 and 9, and have
> >> clk_enable/disable operate on both the current parent and the new
> >> parent.  They would also need to refcount the extra enables separately
> >> to undo on the old parent.
> >>
> >> >  * tglx and I have been discussing different ways of passing clock information
> >> >   to the clock hardware implementation. I'm proposing providing a base 'struct
> >> >   clk_hw', which implementations subclass by wrapping in their own structure
> >> >   (or one of a set of simple 'library' structures, like clk_hw_mux or
> >> >   clk_hw_gate).  The clk_hw base is passed as the first argument to all
> >> >   clk_hw_ops callbacks.
> >> >
> >> >   tglx's plan is to create a separate struct clk_hwdata, which contains a
> >> >   union of base data structures for common clocks: div, mux, gate, etc. The
> >> >   ops callbacks are passed a clk_hw, plus a clk_hwdata, and most of the base
> >> >   hwdata fields are handled within the core clock code. This means less
> >> >   encapsulation of clock implementation logic, but more coverage of
> >> >   clock basics through the core code.
> >>
> >> I don't think they should be a union, I think there should be 3
> >> separate private datas, and three sets of clock ops, for the three
> >> different types of clock blocks: rate changers (dividers and plls),
> >> muxes, and gates.  These blocks are very often combined - a device
> >> clock often has a mux and a divider, and clk_set_parent and
> >> clk_set_rate on the same struct clk both need to work.
> >>
> >> >   tglx, could you send some details about your approach? I'm aiming to refine
> >> >   this series with the good bits from each technique.
> >> >
> >> >  * The clock registration code probably needs work. This is the domain
> >> >   of the platform/board maintainers, any wishes here?
> > When clock init, data in struct clk may not be synced with hw registers. After
> > enabled minimal needed clk (cpu, core bus etc), we need sync the whole tree,
> > disable zero enable_count clocks, set correct .rate ... . The sync function
> > is also common code, right? but not have to be called all times I think.
> 
> I believe each clock is synced with its hardware during clk_register
> by calling the recalc_rate and get_parent callbacks.
so how to sync gate bits? Let subarch to set registers directly or clk_enable and
clk_disable to make sure clk is disabled? Neither way is good I think.

Thanks
Richard
> 
> > Thanks
> > Richard
> >> >
> >> > Cheers,
> >> >
> >> >
> >> > Jeremy
> >> >
> >> > --
> >> >
> >> > ---
> >> > Jeremy Kerr (4):
> >> >      clk: Add a generic clock infrastructure
> >> >      clk: Implement clk_set_rate
> >> >      clk: Add fixed-rate clock
> >> >      clk: Add simple gated clock
> >> >
> >> > --
> >> > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> >> > the body of a message to majordomo@vger.kernel.org
> >> > More majordomo info at  http://vger.kernel.org/majordomo-info.html
> >> > Please read the FAQ at  http://www.tux.org/lkml/
> >> >
> >>
> >> _______________________________________________
> >> linux-arm-kernel mailing list
> >> linux-arm-kernel@lists.infradead.org
> >> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
> >
> 
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
> 

WARNING: multiple messages have this Message-ID
From: linuxzsc@gmail.com (Richard Zhao)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 0/4] Add a generic struct clk
Date: Wed, 25 May 2011 10:08:51 +0800	[thread overview]
Message-ID: <20110525020850.GA2173@b20223-02.ap.freescale.net> (raw)
In-Reply-To: <BANLkTimY1cxqaPG1T=_xKPustXR1GSmUKQ@mail.gmail.com>

On Tue, May 24, 2011 at 10:52:53AM -0700, Colin Cross wrote:
> On Tue, May 24, 2011 at 10:22 AM, Richard Zhao <linuxzsc@gmail.com> wrote:
> > On Mon, May 23, 2011 at 04:12:24PM -0700, Colin Cross wrote:
> >> On Fri, May 20, 2011 at 12:27 AM, Jeremy Kerr <jeremy.kerr@canonical.com> wrote:
> >> > [This series was originally titled 'Add a common struct clk', but
> >> > the goals have changed since that first set of patches. We're now aiming
> >> > for a more complete generic clock infrastructure, rather than just
> >> > abstracting struct clk]
> >> >
> >> > [This series still needs work, see the TODO section below]
> >> >
> >> > [Totally RFC at the moment]
> >> >
> >> > Hi all,
> >> >
> >> > These patches are an attempt to allow platforms to share clock code. At
> >> > present, the definitions of 'struct clk' are local to platform code,
> >> > which makes allocating and initialising cross-platform clock sources
> >> > difficult, and makes it impossible to compile a single image containing
> >> > support for two ARM platforms with different struct clks.
> >> >
> >> > The three patches are for the architecture-independent kernel code,
> >> > introducing the common clk infrastructure. The changelog for the first
> >> > patch includes details about the new clock definitions.
> >> >
> >> > The second patch implements clk_set_rate, and in doing so adds
> >> > functionality to walk the clock tree in both directions.
> >> >
> >> > clk_set_parent is left unimplemented, see TODO below for why.
> >> >
> >> > The third and fourth patches provide some basic clocks (fixed-rate and
> >> > gated), mostly to serve as an example of the hardware implementation.
> >> > I'm intending to later provide similar base clocks for mux and divider
> >> > hardware clocks.
> >> >
> >> > Many thanks to the following for their input:
> >> > ?* Benjamin Herrenschmidt <benh@kernel.crashing.org>
> >> > ?* Thomas Gleixner <tglx@linutronix.de>
> >> > ?* Ben Dooks <ben-linux@fluff.org>
> >> > ?* Baruch Siach <baruch@tkos.co.il>
> >> > ?* Russell King <linux@arm.linux.org.uk>
> >> > ?* Uwe Kleine-K?nig <u.kleine-koenig@pengutronix.de>
> >> > ?* Lorenzo Pieralisi <Lorenzo.Pieralisi@arm.com>
> >> > ?* Vincent Guittot <vincent.guittot@linaro.org>
> >> > ?* Sascha Hauer <s.hauer@pengutronix.de>
> >> > ?* Ryan Mallon <ryan@bluewatersys.com>
> >> > ?* Colin Cross <ccross@google.com>
> >> > ?* Jassi Brar <jassisinghbrar@gmail.com>
> >> > ?* Saravana Kannan <skannan@codeaurora.org>
> >>
> >> I have a similar set of patches I was working on that handles a little
> >> more of the common code than these. ?I can post them if you want, but
> >> for now I'll just point out where I had different ideas, and not muddy
> >> the waters with conflicting patches.
> >>
> >> > TODO:
> >> >
> >> > ?* Need to figure out the locking around clk_set_parent. Changing the in-kernel
> >> > ? clock topology requires acquiring both the mutex (to prevent against races
> >> > ? with clk_prepare, which may propagate to the parent clock) and the spinlock
> >> > ? (to prevent the same race with clk_enable).
> >> >
> >> > ? However, we should also be changing the hardware clock topology in sync with
> >> > ? the in-kernel clock topology, which would imply that both locks *also* need
> >> > ? to be held while updating the parent in the hardware (ie, in
> >> > ? clk_hw_ops->set_parent) too. ?However, I believe some platform clock
> >> > ? implementations may require this callback to be able to sleep. Comments?
> >>
> >> This sequence is the best I could come up with without adding a
> >> temporary 2nd parent:
> >> 1. lock prepare mutex
> > Maybe tell child clocks "I'm going to change clock rate, please stop work if needed"
> >> 2. call prepare on the new parent if prepare_count > 0
> >> 3. lock the enable spinlock
> >> 4. call enable on the new parent if enable_count > 0
> >> 5. change the parent pointer to the new parent
> >> 6. unlock the spinlock
> >> 7. call the set_parent callback
> > Why do it need to sleep if it only set some hw registers?
> 
> Most implementations don't, and I would be fine with saying
> clk_set_parent sleeps, but the set_parent op does not, but that
> prevents clock chips on sleeping busses like i2c.
So it worth to involve a flag here, which says hw_ops may sleep. At least for
on-SoC clocks, we don't need to take risk.
> 
> >> 8. lock the enable spinlock
> >> 9. call disable on the old parent iff you called enable on the new
> >> parent (enable_count may have changed)
> >> 10. unlock the enable spinlock
> >> 11. call unprepare on the old parent if prepare_count
> > propagate rate here and also tell child clocks "rate changed already, change your
> > parameters and go on to work".
> 
> Yes, propagate rate is needed.
> 
> >> 12. unlock prepare mutex
> >>
> >> The only possible problem I see is that if a clock starts disabled at
> >> step 1., and clk_enable is called on it between steps 6 and 7,
> >> clk_enable will return having enabled the new parent, but the clock is
> >> still running off the old parent. ?As soon as the clock gets switched
> >> to the new parent, the clock will be properly enabled. ?I don't see
> >> this as a huge problem - calling clk_set_parent on a clock while it is
> >> enabled may not even work without causing glitches on some platforms.
> > some do be glitch free, especially for cpu clock parents.
> >>
> >> I guess the only way around it would be to store a temporary
> >> "new_parent" pointer between steps 5 and 9, and have
> >> clk_enable/disable operate on both the current parent and the new
> >> parent. ?They would also need to refcount the extra enables separately
> >> to undo on the old parent.
> >>
> >> > ?* tglx and I have been discussing different ways of passing clock information
> >> > ? to the clock hardware implementation. I'm proposing providing a base 'struct
> >> > ? clk_hw', which implementations subclass by wrapping in their own structure
> >> > ? (or one of a set of simple 'library' structures, like clk_hw_mux or
> >> > ? clk_hw_gate). ?The clk_hw base is passed as the first argument to all
> >> > ? clk_hw_ops callbacks.
> >> >
> >> > ? tglx's plan is to create a separate struct clk_hwdata, which contains a
> >> > ? union of base data structures for common clocks: div, mux, gate, etc. The
> >> > ? ops callbacks are passed a clk_hw, plus a clk_hwdata, and most of the base
> >> > ? hwdata fields are handled within the core clock code. This means less
> >> > ? encapsulation of clock implementation logic, but more coverage of
> >> > ? clock basics through the core code.
> >>
> >> I don't think they should be a union, I think there should be 3
> >> separate private datas, and three sets of clock ops, for the three
> >> different types of clock blocks: rate changers (dividers and plls),
> >> muxes, and gates. ?These blocks are very often combined - a device
> >> clock often has a mux and a divider, and clk_set_parent and
> >> clk_set_rate on the same struct clk both need to work.
> >>
> >> > ? tglx, could you send some details about your approach? I'm aiming to refine
> >> > ? this series with the good bits from each technique.
> >> >
> >> > ?* The clock registration code probably needs work. This is the domain
> >> > ? of the platform/board maintainers, any wishes here?
> > When clock init, data in struct clk may not be synced with hw registers. After
> > enabled minimal needed clk (cpu, core bus etc), we need sync the whole tree,
> > disable zero enable_count clocks, set correct .rate ... . The sync function
> > is also common code, right? but not have to be called all times I think.
> 
> I believe each clock is synced with its hardware during clk_register
> by calling the recalc_rate and get_parent callbacks.
so how to sync gate bits? Let subarch to set registers directly or clk_enable and
clk_disable to make sure clk is disabled? Neither way is good I think.

Thanks
Richard
> 
> > Thanks
> > Richard
> >> >
> >> > Cheers,
> >> >
> >> >
> >> > Jeremy
> >> >
> >> > --
> >> >
> >> > ---
> >> > Jeremy Kerr (4):
> >> > ? ? ?clk: Add a generic clock infrastructure
> >> > ? ? ?clk: Implement clk_set_rate
> >> > ? ? ?clk: Add fixed-rate clock
> >> > ? ? ?clk: Add simple gated clock
> >> >
> >> > --
> >> > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> >> > the body of a message to majordomo at vger.kernel.org
> >> > More majordomo info at ?http://vger.kernel.org/majordomo-info.html
> >> > Please read the FAQ at ?http://www.tux.org/lkml/
> >> >
> >>
> >> _______________________________________________
> >> linux-arm-kernel mailing list
> >> linux-arm-kernel at lists.infradead.org
> >> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
> >
> 
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel at lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
> 

  reply	other threads:[~2011-05-25  2:08 UTC|newest]

Thread overview: 139+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-05-20  7:27 Jeremy Kerr
2011-05-20  7:27 ` Jeremy Kerr
2011-05-20  7:27 ` Jeremy Kerr
2011-05-20  7:27 ` [PATCH 4/4] clk: Add simple gated clock Jeremy Kerr
2011-05-20  7:27   ` Jeremy Kerr
2011-05-20  7:27   ` Jeremy Kerr
2011-05-20 11:37   ` Arnd Bergmann
2011-05-20 11:37     ` Arnd Bergmann
2011-05-20 11:37     ` Arnd Bergmann
2011-05-20 22:19   ` Rob Herring
2011-05-20 22:19     ` Rob Herring
2011-05-20 22:19     ` Rob Herring
2011-05-20  7:27 ` [PATCH 2/4] clk: Implement clk_set_rate Jeremy Kerr
2011-05-20  7:27   ` Jeremy Kerr
2011-05-20  7:27   ` Jeremy Kerr
2011-05-20 12:25   ` Sascha Hauer
2011-05-20 12:25     ` Sascha Hauer
2011-05-20 12:25     ` Sascha Hauer
2011-05-24  7:59   ` Colin Cross
2011-05-24  7:59     ` Colin Cross
2011-05-24  7:59     ` Colin Cross
2011-05-25 19:03   ` Sascha Hauer
2011-05-25 19:03     ` Sascha Hauer
2011-05-25 19:03     ` Sascha Hauer
     [not found]     ` <1306373867.2875.162.camel@pororo>
2011-05-26  6:54       ` Sascha Hauer
2011-05-26  6:54         ` Sascha Hauer
2011-05-26  6:54         ` Sascha Hauer
2011-05-30  5:05   ` Mike Frysinger
2011-05-30  5:05     ` Mike Frysinger
2011-05-30  5:05     ` Mike Frysinger
2011-05-20  7:27 ` [PATCH 3/4] clk: Add fixed-rate clock Jeremy Kerr
2011-05-20  7:27   ` Jeremy Kerr
2011-05-20  7:27   ` Jeremy Kerr
2011-05-24  7:01   ` Francesco VIRLINZI
2011-05-30  5:01   ` Mike Frysinger
2011-05-30  5:01     ` Mike Frysinger
2011-05-30  5:01     ` Mike Frysinger
2011-05-30  5:02   ` Mike Frysinger
2011-05-30  5:02     ` Mike Frysinger
2011-05-30  5:02     ` Mike Frysinger
2011-05-20  7:27 ` [PATCH 1/4] clk: Add a generic clock infrastructure Jeremy Kerr
2011-05-20  7:27   ` Jeremy Kerr
2011-05-20  7:27   ` Jeremy Kerr
2011-05-20 11:59   ` Sascha Hauer
2011-05-20 11:59     ` Sascha Hauer
2011-05-20 11:59     ` Sascha Hauer
2011-05-20 13:25     ` Thomas Gleixner
2011-05-20 13:25       ` Thomas Gleixner
2011-05-20 13:25       ` Thomas Gleixner
2011-05-20 13:36       ` Sascha Hauer
2011-05-20 13:36         ` Sascha Hauer
2011-05-20 13:36         ` Sascha Hauer
2011-05-23 23:55   ` Colin Cross
2011-05-23 23:55     ` Colin Cross
2011-05-23 23:55     ` Colin Cross
2011-05-24  7:02     ` Sascha Hauer
2011-05-24  7:02       ` Sascha Hauer
2011-05-24  7:02       ` Sascha Hauer
2011-05-24  7:51       ` Colin Cross
2011-05-24  7:51         ` Colin Cross
2011-05-24  7:51         ` Colin Cross
2011-05-24  8:38         ` Sascha Hauer
2011-05-24  8:38           ` Sascha Hauer
2011-05-24  8:38           ` Sascha Hauer
2011-05-25 11:22           ` Richard Zhao
2011-05-25 11:22             ` Richard Zhao
2011-05-25 11:22             ` Richard Zhao
2011-05-25 11:43         ` Thomas Gleixner
2011-05-25 11:43           ` Thomas Gleixner
2011-05-25 11:43           ` Thomas Gleixner
2011-05-24  4:18   ` viresh kumar
2011-05-24  4:30     ` viresh kumar
2011-05-24  4:18     ` viresh kumar
2011-05-25 10:47   ` Richard Zhao
2011-05-25 10:47     ` Richard Zhao
2011-05-25 10:47     ` Richard Zhao
2011-05-30  5:00     ` Mike Frysinger
2011-05-30  5:00       ` Mike Frysinger
2011-05-30  5:00       ` Mike Frysinger
2011-05-23 23:12 ` [PATCH 0/4] Add a generic struct clk Colin Cross
2011-05-23 23:12   ` Colin Cross
2011-05-23 23:12   ` Colin Cross
2011-05-24  6:26   ` Sascha Hauer
2011-05-24  6:26     ` Sascha Hauer
2011-05-24  6:26     ` Sascha Hauer
2011-05-24  7:31     ` Colin Cross
2011-05-24  7:31       ` Colin Cross
2011-05-24  7:31       ` Colin Cross
2011-05-24  8:09       ` Sascha Hauer
2011-05-24  8:09         ` Sascha Hauer
2011-05-24  8:09         ` Sascha Hauer
2011-05-24 19:41         ` Colin Cross
2011-05-24 19:41           ` Colin Cross
2011-05-24 19:41           ` Colin Cross
2011-05-25  2:32           ` Richard Zhao
2011-05-25  2:32             ` Richard Zhao
2011-05-25  2:32             ` Richard Zhao
2011-05-25  6:23           ` Sascha Hauer
2011-05-25  6:23             ` Sascha Hauer
2011-05-25  6:23             ` Sascha Hauer
2011-05-25  7:51           ` Thomas Gleixner
2011-05-25  7:51             ` Thomas Gleixner
2011-05-25  7:51             ` Thomas Gleixner
2011-05-27 14:39           ` Mark Brown
2011-05-27 14:39             ` Mark Brown
2011-05-27 14:39             ` Mark Brown
2011-05-24 17:22   ` Richard Zhao
2011-05-24 17:22     ` Richard Zhao
2011-05-24 17:22     ` Richard Zhao
2011-05-24 17:52     ` Colin Cross
2011-05-24 17:52       ` Colin Cross
2011-05-24 17:52       ` Colin Cross
2011-05-25  2:08       ` Richard Zhao [this message]
2011-05-25  2:08         ` Richard Zhao
2011-05-25  2:08         ` Richard Zhao
2011-05-30  5:20 ` Mike Frysinger
2011-05-30  5:20   ` Mike Frysinger
2011-05-30  5:20   ` Mike Frysinger
2011-07-10  9:09 ` Mark Brown
2011-07-10  9:09   ` Mark Brown
2011-07-10  9:09   ` Mark Brown
2011-07-10  9:50   ` Russell King - ARM Linux
2011-07-10  9:50     ` Russell King - ARM Linux
2011-07-10  9:50     ` Russell King - ARM Linux
2011-07-10 10:00     ` Russell King - ARM Linux
2011-07-10 10:00       ` Russell King - ARM Linux
2011-07-10 10:00       ` Russell King - ARM Linux
2011-07-10 11:27     ` Mark Brown
2011-07-10 11:27       ` Mark Brown
2011-07-10 11:27       ` Mark Brown
2011-07-10 11:52       ` Russell King - ARM Linux
2011-07-10 11:52         ` Russell King - ARM Linux
2011-07-10 11:52         ` Russell King - ARM Linux
2011-07-11  2:49   ` Jeremy Kerr
2011-07-11  2:49     ` Jeremy Kerr
2011-07-11  2:49     ` Jeremy Kerr
2011-07-11  3:57     ` Mark Brown
2011-07-11  3:57       ` Mark Brown
2011-07-11  3:57       ` Mark Brown

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