Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-10-18 Thread Sergei Shtylyov
Sergei Shtylyov wrote: Add PowerPC decrementer clock event driver. Every effort has been made to support the different implementations of the decrementer: the classic one (with 970 series variation), 40x and Book E specific ones. I had to make CONFIG_GENERIC_CLOCKEVENTS option selectable

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-10-18 Thread Sergei Shtylyov
Sergei Shtylyov wrote: Add PowerPC decrementer clock event driver. Every effort has been made to support the different implementations of the decrementer: the classic one (with 970 series variation), 40x and Book E specific ones. I had to make CONFIG_GENERIC_CLOCKEVENTS option selectable

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-07-10 Thread Segher Boessenkool
This scales with the number of processors since there is one decrementer per core (is it per thread on SMT chips? I don't know). One per core. No, each thread has its own decrementer, but the timebase is shared. Argh, of course you're right, I'm reading the wrong ISA version again. Sorry.

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-07-10 Thread Paul Mackerras
Segher Boessenkool writes: > > This scales with the number of processors since there is one > > decrementer per core (is it per thread on SMT chips? > > I don't know). > > One per core. No, each thread has its own decrementer, but the timebase is shared. Paul. - To unsubscribe from this list:

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-07-10 Thread Segher Boessenkool
This scales with the number of processors since there is one decrementer per core (is it per thread on SMT chips? I don't know). One per core. Segher - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-07-10 Thread Gabriel Paubert
On Fri, May 18, 2007 at 05:52:45PM +0100, Matt Sealey wrote: > Kumar Gala wrote: > > > > On May 18, 2007, at 9:48 AM, Thomas Gleixner wrote: > > > >> On Fri, 2007-05-18 at 15:28 +0100, Matt Sealey wrote: > >>> > >>> I think both the MPC52xx GPT0-7 and the SLT0-1 fulfil this fairly > >>> easily.

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-07-10 Thread Gabriel Paubert
On Fri, May 18, 2007 at 05:52:45PM +0100, Matt Sealey wrote: Kumar Gala wrote: On May 18, 2007, at 9:48 AM, Thomas Gleixner wrote: On Fri, 2007-05-18 at 15:28 +0100, Matt Sealey wrote: I think both the MPC52xx GPT0-7 and the SLT0-1 fulfil this fairly easily. There is some

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-07-10 Thread Segher Boessenkool
This scales with the number of processors since there is one decrementer per core (is it per thread on SMT chips? I don't know). One per core. Segher - To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to [EMAIL PROTECTED] More majordomo info at

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-07-10 Thread Paul Mackerras
Segher Boessenkool writes: This scales with the number of processors since there is one decrementer per core (is it per thread on SMT chips? I don't know). One per core. No, each thread has its own decrementer, but the timebase is shared. Paul. - To unsubscribe from this list: send the

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-07-10 Thread Segher Boessenkool
This scales with the number of processors since there is one decrementer per core (is it per thread on SMT chips? I don't know). One per core. No, each thread has its own decrementer, but the timebase is shared. Argh, of course you're right, I'm reading the wrong ISA version again. Sorry.

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-05-20 Thread Benjamin Herrenschmidt
On Sun, 2007-05-20 at 18:02 +0200, Segher Boessenkool wrote: > > In fact, while it's never worded explicitely in the spec, it's always > > been strongly in the "spirit" of the architecture that the timebase and > > decrementer have a constant frequency. > > The architecture mentions varying time

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-05-20 Thread Benjamin Herrenschmidt
> So.. if we get enough clocksources into the tree, can any of those > parts of the code be reworked to use clocksources/clockevents and > hrtimers quickly and easily? I noticed the patch just posted does > some of it.. but not as much as Ben just mentioned. Well, some of these are expected to be

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-05-20 Thread Segher Boessenkool
In fact, while it's never worded explicitely in the spec, it's always been strongly in the "spirit" of the architecture that the timebase and decrementer have a constant frequency. The architecture mentions varying time base frequencies, and how to deal with this, actually. It makes no

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-05-20 Thread Matt Sealey
Benjamin Herrenschmidt wrote: > On Sat, 2007-05-19 at 19:43 -0700, Daniel Walker wrote: > >> In terms of clocksources, gettimeofday() would have to switch to another >> clocksource if the decrementer started to act that way .. That's why it >> is possible to register more than one clocksource,

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-05-20 Thread Matt Sealey
Benjamin Herrenschmidt wrote: On Sat, 2007-05-19 at 19:43 -0700, Daniel Walker wrote: In terms of clocksources, gettimeofday() would have to switch to another clocksource if the decrementer started to act that way .. That's why it is possible to register more than one clocksource, to allow

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-05-20 Thread Segher Boessenkool
In fact, while it's never worded explicitely in the spec, it's always been strongly in the spirit of the architecture that the timebase and decrementer have a constant frequency. The architecture mentions varying time base frequencies, and how to deal with this, actually. It makes no

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-05-20 Thread Benjamin Herrenschmidt
So.. if we get enough clocksources into the tree, can any of those parts of the code be reworked to use clocksources/clockevents and hrtimers quickly and easily? I noticed the patch just posted does some of it.. but not as much as Ben just mentioned. Well, some of these are expected to be

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-05-20 Thread Benjamin Herrenschmidt
On Sun, 2007-05-20 at 18:02 +0200, Segher Boessenkool wrote: In fact, while it's never worded explicitely in the spec, it's always been strongly in the spirit of the architecture that the timebase and decrementer have a constant frequency. The architecture mentions varying time base

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-05-19 Thread Benjamin Herrenschmidt
On Sat, 2007-05-19 at 19:43 -0700, Daniel Walker wrote: > In terms of clocksources, gettimeofday() would have to switch to another > clocksource if the decrementer started to act that way .. That's why it > is possible to register more than one clocksource, to allow for the > switching. The

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-05-19 Thread Daniel Walker
On Sat, 2007-05-19 at 13:33 +1000, Paul Mackerras wrote: > Daniel Walker writes: > > > On Fri, 2007-05-18 at 19:06 +0400, Sergei Shtylyov wrote: > > > Well, the decrementer frequency may change, at least in theory (if > > > the bus > > > clock changes). > > > > Does that happen very

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-05-19 Thread Albert Cahalan
On 5/19/07, Segher Boessenkool <[EMAIL PROTECTED]> wrote: [Albert Cahalan] > Set MMCR0[TBEE], set MMCR0[PMXE], and choose a TBL bit via > MMCR0[TBSEL]. That's the performance monitor, which could very well be in use already (for performance monitoring stuff, who would have guessed). It is

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-05-19 Thread Segher Boessenkool
Unfortunately, FIT exists only on Book E CPUs and MPC74xx aren't Book E, IIUC. By the name "FIT" perhaps, but MPC74xx has essentially the same thing. Set MMCR0[TBEE], set MMCR0[PMXE], and choose a TBL bit via MMCR0[TBSEL]. That's the performance monitor, which could very well be in use

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-05-19 Thread Segher Boessenkool
Unfortunately, FIT exists only on Book E CPUs and MPC74xx aren't Book E, IIUC. By the name FIT perhaps, but MPC74xx has essentially the same thing. Set MMCR0[TBEE], set MMCR0[PMXE], and choose a TBL bit via MMCR0[TBSEL]. That's the performance monitor, which could very well be in use

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-05-19 Thread Albert Cahalan
On 5/19/07, Segher Boessenkool [EMAIL PROTECTED] wrote: [Albert Cahalan] Set MMCR0[TBEE], set MMCR0[PMXE], and choose a TBL bit via MMCR0[TBSEL]. That's the performance monitor, which could very well be in use already (for performance monitoring stuff, who would have guessed). It is the

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-05-19 Thread Daniel Walker
On Sat, 2007-05-19 at 13:33 +1000, Paul Mackerras wrote: Daniel Walker writes: On Fri, 2007-05-18 at 19:06 +0400, Sergei Shtylyov wrote: Well, the decrementer frequency may change, at least in theory (if the bus clock changes). Does that happen very often? If it did,

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-05-19 Thread Benjamin Herrenschmidt
On Sat, 2007-05-19 at 19:43 -0700, Daniel Walker wrote: In terms of clocksources, gettimeofday() would have to switch to another clocksource if the decrementer started to act that way .. That's why it is possible to register more than one clocksource, to allow for the switching. The

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-05-18 Thread Paul Mackerras
Daniel Walker writes: > On Fri, 2007-05-18 at 19:06 +0400, Sergei Shtylyov wrote: > > Well, the decrementer frequency may change, at least in theory (if the > > bus > > clock changes). > > Does that happen very often? If it did, gettimeofday would start reporting seriously wrong values,

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-05-18 Thread Paul Mackerras
Sergei Shtylyov writes: > Yeah, the classic decrementer is programmed off-by-one. Actually it's programmed off by slightly less than one half on average, but it doesn't matter since the error doesn't accumulate. Paul. - To unsubscribe from this list: send the line "unsubscribe linux-kernel"

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-05-18 Thread Albert Cahalan
On 5/18/07, Sergei Shtylyov <[EMAIL PROTECTED]> wrote: Albert Cahalan wrote: >>> Sure, but is there any utility in registering more than the >>> decrementer on PPC? >> Not yet. I'm not sure I know any other PPC CPU facility fitting >> for clockevents. In theory, FIT could be used -- but its

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-05-18 Thread Benjamin Herrenschmidt
On Sat, 2007-05-19 at 01:49 +0200, Segher Boessenkool wrote: > > I find it extremely silly to implement it as edge anyway. The EE line > > is > > level triggered, and having a mix of edge and level on the same > > exception without a clean way to retrigger the DEC one other than > > waiting one

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-05-18 Thread Segher Boessenkool
I find it extremely silly to implement it as edge anyway. The EE line is level triggered, and having a mix of edge and level on the same exception without a clean way to retrigger the DEC one other than waiting one tick is just causing trouble. It isn't edge triggered, it just automatically

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-05-18 Thread Benjamin Herrenschmidt
On Fri, 2007-05-18 at 17:41 +0400, Sergei Shtylyov wrote: > From the "PowerPC Operating Environment Architecture" that I've > already > quoated t follows that POWER4-compatible decremented exception *must* > be edge > triggered. > > > says that an exception is generated when the MSB

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-05-18 Thread David Miller
From: Kumar Gala <[EMAIL PROTECTED]> Date: Fri, 18 May 2007 11:31:19 -0500 > I asked this earlier, but figured you might have a better insight. > Is their value in having 'drivers' for more than one clock source? > I'd say most (of not all) the PPC SoCs have timers on the system side >

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-05-18 Thread Matt Sealey
Thomas Gleixner wrote: > On Fri, 2007-05-18 at 11:31 -0500, Kumar Gala wrote: >> I asked this earlier, but figured you might have a better insight. >> Is their value in having 'drivers' for more than one clock source? >> I'd say most (of not all) the PPC SoCs have timers on the system side

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-05-18 Thread Matt Sealey
Kumar Gala wrote: > > On May 18, 2007, at 9:48 AM, Thomas Gleixner wrote: > >> On Fri, 2007-05-18 at 15:28 +0100, Matt Sealey wrote: >>> >>> I think both the MPC52xx GPT0-7 and the SLT0-1 fulfil this fairly >>> easily. >> >> There is some basic work for MPC5200 available: >> >>

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-05-18 Thread Thomas Gleixner
On Fri, 2007-05-18 at 11:31 -0500, Kumar Gala wrote: > I asked this earlier, but figured you might have a better insight. > Is their value in having 'drivers' for more than one clock source? > I'd say most (of not all) the PPC SoCs have timers on the system side > that we could provide

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-05-18 Thread Kumar Gala
On May 18, 2007, at 9:48 AM, Thomas Gleixner wrote: On Fri, 2007-05-18 at 15:28 +0100, Matt Sealey wrote: I guess the real question is, how high resolution does a high resolution timer need to be, In the order of microseconds. I think both the MPC52xx GPT0-7 and the SLT0-1 fulfil

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-05-18 Thread Sergei Shtylyov
Hello. Daniel Walker wrote: Well, the decrementer frequency may change, at least in theory (if the bus clock changes). Does that happen very often? Never, I hope. :-) Daniel WBR, Sergei - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-05-18 Thread Daniel Walker
On Fri, 2007-05-18 at 19:06 +0400, Sergei Shtylyov wrote: > Daniel Walker wrote: > > >>I haven't looked at all the new clock/timer code, is there any > >>utility in having support for more than one clock source? > > > There is if the main clocksource has some issues where it can't be used. >

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-05-18 Thread Matt Sealey
I already have that stuff, but it only implements the decrementer (in fact it's the patch submitted at the beginning of this thread). I got it because I was far more interested in the GPIO handling.. -- Matt Sealey <[EMAIL PROTECTED]> Genesi, Manager, Developer Relations Thomas Gleixner wrote:

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-05-18 Thread Sergei Shtylyov
Daniel Walker wrote: I haven't looked at all the new clock/timer code, is there any utility in having support for more than one clock source? There is if the main clocksource has some issues where it can't be used. You mean, having more than one clocksource is *useful* in this case?

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-05-18 Thread Daniel Walker
On Thu, 2007-05-17 at 13:17 -0500, Kumar Gala wrote: > > I haven't looked at all the new clock/timer code, is there any > utility in having support for more than one clock source? There is if the main clocksource has some issues where it can't be used. On x86 there are lots of different

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-05-18 Thread Sergei Shtylyov
Hello. Albert Cahalan wrote: I haven't looked at all the new clock/timer code, is there any utility in having support for more than one clock source? Of course, you may register as many as you like. Sure, but is there any utility in registering more than the decrementer on PPC? Not

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-05-18 Thread Thomas Gleixner
On Fri, 2007-05-18 at 15:28 +0100, Matt Sealey wrote: > >> I guess the real question is, how high resolution does a high resolution > >> timer need to be, > > > >In the order of microseconds. > > I think both the MPC52xx GPT0-7 and the SLT0-1 fulfil this fairly > easily. There is some basic

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-05-18 Thread Matt Sealey
Sergei Shtylyov wrote: > Hello. > Sure, but is there any utility in registering more than the decrementer on PPC? > >>>Not yet. I'm not sure I know any other PPC CPU facility fitting >>> for clockevents. In theory, FIT could be used -- but its period is >>> measured in powers of

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-05-18 Thread Sergei Shtylyov
Hello, I wrote: Yes, on some implementations there can be other conditions that make a decrementer exception go away; there is no contradiction here (thankfully). My wording was sloppy. Some CPUs have the DEC exceptions basically edge triggered (yeah I know for example? it sucks).

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-05-18 Thread Sergei Shtylyov
Hello. Matt Sealey wrote: I haven't looked at all the new clock/timer code, is there any utility in having support for more than one clock source? Of course, you may register as many as you like. Sure, but is there any utility in registering more than the decrementer on PPC?

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-05-18 Thread Sergei Shtylyov
Hello. Benjamin Herrenschmidt wrote: Yes, on some implementations there can be other conditions that make a decrementer exception go away; there is no contradiction here (thankfully). My wording was sloppy. Some CPUs have the DEC exceptions basically edge triggered (yeah I know for

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-05-18 Thread Matt Sealey
Sergei Shtylyov wrote: > Hello. > > Kumar Gala wrote: > >>> Kumar Gala wrote: > I haven't looked at all the new clock/timer code, is there any utility in having support for more than one clock source? > >>>Of course, you may register as many as you like. > >> Sure, but is

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-05-18 Thread Benjamin Herrenschmidt
On Fri, 2007-05-18 at 13:39 +0800, Dave Liu wrote: > > > Yes, on some implementations there can be other conditions that > > > make a decrementer exception go away; there is no contradiction > > > here (thankfully). My wording was sloppy. > > > > Some CPUs have the DEC exceptions basically edge

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-05-18 Thread Benjamin Herrenschmidt
On Fri, 2007-05-18 at 13:39 +0800, Dave Liu wrote: Yes, on some implementations there can be other conditions that make a decrementer exception go away; there is no contradiction here (thankfully). My wording was sloppy. Some CPUs have the DEC exceptions basically edge triggered

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-05-18 Thread Matt Sealey
Sergei Shtylyov wrote: Hello. Kumar Gala wrote: Kumar Gala wrote: I haven't looked at all the new clock/timer code, is there any utility in having support for more than one clock source? Of course, you may register as many as you like. Sure, but is there any utility in

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-05-18 Thread Sergei Shtylyov
Hello. Benjamin Herrenschmidt wrote: Yes, on some implementations there can be other conditions that make a decrementer exception go away; there is no contradiction here (thankfully). My wording was sloppy. Some CPUs have the DEC exceptions basically edge triggered (yeah I know for

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-05-18 Thread Sergei Shtylyov
Hello. Matt Sealey wrote: I haven't looked at all the new clock/timer code, is there any utility in having support for more than one clock source? Of course, you may register as many as you like. Sure, but is there any utility in registering more than the decrementer on PPC?

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-05-18 Thread Sergei Shtylyov
Hello, I wrote: Yes, on some implementations there can be other conditions that make a decrementer exception go away; there is no contradiction here (thankfully). My wording was sloppy. Some CPUs have the DEC exceptions basically edge triggered (yeah I know for example? it sucks).

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-05-18 Thread Matt Sealey
Sergei Shtylyov wrote: Hello. Sure, but is there any utility in registering more than the decrementer on PPC? Not yet. I'm not sure I know any other PPC CPU facility fitting for clockevents. In theory, FIT could be used -- but its period is measured in powers of 2, IIRC. Wouldn't

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-05-18 Thread Thomas Gleixner
On Fri, 2007-05-18 at 15:28 +0100, Matt Sealey wrote: I guess the real question is, how high resolution does a high resolution timer need to be, In the order of microseconds. I think both the MPC52xx GPT0-7 and the SLT0-1 fulfil this fairly easily. There is some basic work for

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-05-18 Thread Sergei Shtylyov
Hello. Albert Cahalan wrote: I haven't looked at all the new clock/timer code, is there any utility in having support for more than one clock source? Of course, you may register as many as you like. Sure, but is there any utility in registering more than the decrementer on PPC? Not

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-05-18 Thread Sergei Shtylyov
Daniel Walker wrote: I haven't looked at all the new clock/timer code, is there any utility in having support for more than one clock source? There is if the main clocksource has some issues where it can't be used. You mean, having more than one clocksource is *useful* in this case?

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-05-18 Thread Daniel Walker
On Thu, 2007-05-17 at 13:17 -0500, Kumar Gala wrote: I haven't looked at all the new clock/timer code, is there any utility in having support for more than one clock source? There is if the main clocksource has some issues where it can't be used. On x86 there are lots of different issues

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-05-18 Thread Matt Sealey
I already have that stuff, but it only implements the decrementer (in fact it's the patch submitted at the beginning of this thread). I got it because I was far more interested in the GPIO handling.. -- Matt Sealey [EMAIL PROTECTED] Genesi, Manager, Developer Relations Thomas Gleixner wrote:

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-05-18 Thread Daniel Walker
On Fri, 2007-05-18 at 19:06 +0400, Sergei Shtylyov wrote: Daniel Walker wrote: I haven't looked at all the new clock/timer code, is there any utility in having support for more than one clock source? There is if the main clocksource has some issues where it can't be used. You

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-05-18 Thread Sergei Shtylyov
Hello. Daniel Walker wrote: Well, the decrementer frequency may change, at least in theory (if the bus clock changes). Does that happen very often? Never, I hope. :-) Daniel WBR, Sergei - To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-05-18 Thread Matt Sealey
Kumar Gala wrote: On May 18, 2007, at 9:48 AM, Thomas Gleixner wrote: On Fri, 2007-05-18 at 15:28 +0100, Matt Sealey wrote: I think both the MPC52xx GPT0-7 and the SLT0-1 fulfil this fairly easily. There is some basic work for MPC5200 available:

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-05-18 Thread Matt Sealey
Thomas Gleixner wrote: On Fri, 2007-05-18 at 11:31 -0500, Kumar Gala wrote: I asked this earlier, but figured you might have a better insight. Is their value in having 'drivers' for more than one clock source? I'd say most (of not all) the PPC SoCs have timers on the system side that

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-05-18 Thread Thomas Gleixner
On Fri, 2007-05-18 at 11:31 -0500, Kumar Gala wrote: I asked this earlier, but figured you might have a better insight. Is their value in having 'drivers' for more than one clock source? I'd say most (of not all) the PPC SoCs have timers on the system side that we could provide drivers

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-05-18 Thread Kumar Gala
On May 18, 2007, at 9:48 AM, Thomas Gleixner wrote: On Fri, 2007-05-18 at 15:28 +0100, Matt Sealey wrote: I guess the real question is, how high resolution does a high resolution timer need to be, In the order of microseconds. I think both the MPC52xx GPT0-7 and the SLT0-1 fulfil

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-05-18 Thread David Miller
From: Kumar Gala [EMAIL PROTECTED] Date: Fri, 18 May 2007 11:31:19 -0500 I asked this earlier, but figured you might have a better insight. Is their value in having 'drivers' for more than one clock source? I'd say most (of not all) the PPC SoCs have timers on the system side that we

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-05-18 Thread Benjamin Herrenschmidt
On Fri, 2007-05-18 at 17:41 +0400, Sergei Shtylyov wrote: From the PowerPC Operating Environment Architecture that I've already quoated t follows that POWER4-compatible decremented exception *must* be edge triggered. says that an exception is generated when the MSB transitions from

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-05-18 Thread Albert Cahalan
On 5/18/07, Sergei Shtylyov [EMAIL PROTECTED] wrote: Albert Cahalan wrote: Sure, but is there any utility in registering more than the decrementer on PPC? Not yet. I'm not sure I know any other PPC CPU facility fitting for clockevents. In theory, FIT could be used -- but its period is

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-05-18 Thread Paul Mackerras
Daniel Walker writes: On Fri, 2007-05-18 at 19:06 +0400, Sergei Shtylyov wrote: Well, the decrementer frequency may change, at least in theory (if the bus clock changes). Does that happen very often? If it did, gettimeofday would start reporting seriously wrong values, since the

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-05-18 Thread Paul Mackerras
Sergei Shtylyov writes: Yeah, the classic decrementer is programmed off-by-one. Actually it's programmed off by slightly less than one half on average, but it doesn't matter since the error doesn't accumulate. Paul. - To unsubscribe from this list: send the line unsubscribe linux-kernel in

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-05-17 Thread Dave Liu
> > Yes, on some implementations there can be other conditions that > > make a decrementer exception go away; there is no contradiction > > here (thankfully). My wording was sloppy. > > Some CPUs have the DEC exceptions basically edge triggered (yeah I know for example? > it sucks). That's

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-05-17 Thread Benjamin Herrenschmidt
> > Yes, on some implementations there can be other conditions that > make a decrementer exception go away; there is no contradiction > here (thankfully). My wording was sloppy. Some CPUs have the DEC exceptions basically edge triggered (yeah I know it sucks). That's why, among others, the IRQ

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-05-17 Thread Albert Cahalan
Sergei Shtylyov writes: Kumar Gala wrote: [Sergei Shtylyov] Kumar Gala wrote: I haven't looked at all the new clock/timer code, is there any utility in having support for more than one clock source? Of course, you may register as many as you like. Sure, but is there any utility in

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-05-17 Thread Segher Boessenkool
Otherwise, when the contents of DEC0 change, the exception effects of the Decrementer become consistent with the new contents of the Decrementer reasonably soon after the change. And that is guaranteed on all PowerPC as far as I can see. The main thing is that a decrementer exception won't go

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-05-17 Thread Sergei Shtylyov
Segher Boessenkool wrote: + * We must write a positive value to the decrementer to clear + * the interrupt on the IBM 970 CPU series. In periodic mode, + * this happens when the decrementer gets reloaded later, but + * in one-shot mode, we have to do it here since an event

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-05-17 Thread Segher Boessenkool
+ * We must write a positive value to the decrementer to clear + * the interrupt on the IBM 970 CPU series. In periodic mode, + * this happens when the decrementer gets reloaded later, but + * in one-shot mode, we have to do it here since an event handler + * may skip

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-05-17 Thread Sergei Shtylyov
Segher Boessenkool wrote: + * We must write a positive value to the decrementer to clear + * the interrupt on the IBM 970 CPU series. In periodic mode, + * this happens when the decrementer gets reloaded later, but + * in one-shot mode, we have to do it here since an event

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-05-17 Thread Segher Boessenkool
+* We must write a positive value to the decrementer to clear +* the interrupt on the IBM 970 CPU series. In periodic mode, +* this happens when the decrementer gets reloaded later, but +* in one-shot mode, we have to do it here since an event handler +*

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-05-17 Thread Sergei Shtylyov
Hello. Kumar Gala wrote: Kumar Gala wrote: I haven't looked at all the new clock/timer code, is there any utility in having support for more than one clock source? Of course, you may register as many as you like. Sure, but is there any utility in registering more than the

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-05-17 Thread Kumar Gala
On May 17, 2007, at 1:26 PM, Sergei Shtylyov wrote: Hello. Kumar Gala wrote: I haven't looked at all the new clock/timer code, is there any utility in having support for more than one clock source? Of course, you may register as many as you like. Sure, but is there any utility in

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-05-17 Thread Sergei Shtylyov
Hello. Kumar Gala wrote: I haven't looked at all the new clock/timer code, is there any utility in having support for more than one clock source? Of course, you may register as many as you like. - k WBR, Sergei - To unsubscribe from this list: send the line "unsubscribe linux-kernel"

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-05-17 Thread Kumar Gala
On May 17, 2007, at 1:07 PM, Sergei Shtylyov wrote: Hello. Kumar Gala wrote: Index: linux-2.6/arch/powerpc/kernel/time.c === --- linux-2.6.orig/arch/powerpc/kernel/time.c +++ linux-2.6/arch/powerpc/kernel/time.c [...] @@

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-05-17 Thread Sergei Shtylyov
Hello. Kumar Gala wrote: Index: linux-2.6/arch/powerpc/kernel/time.c === --- linux-2.6.orig/arch/powerpc/kernel/time.c +++ linux-2.6/arch/powerpc/kernel/time.c [...] @@ -128,6 +129,83 @@ unsigned long ppc_tb_freq; static u64

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-05-17 Thread Kumar Gala
On May 17, 2007, at 12:42 PM, Sergei Shtylyov wrote: Add PowerPC decrementer clock event driver. Every effort has been made to support the different implementations of the decrementer: the classic one (with 970 series variation), 40x and Book E specific ones. I had to make

[PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-05-17 Thread Sergei Shtylyov
Add PowerPC decrementer clock event driver. Every effort has been made to support the different implementations of the decrementer: the classic one (with 970 series variation), 40x and Book E specific ones. I had to make CONFIG_GENERIC_CLOCKEVENTS option selectable for the compatibility reasons

[PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-05-17 Thread Sergei Shtylyov
Add PowerPC decrementer clock event driver. Every effort has been made to support the different implementations of the decrementer: the classic one (with 970 series variation), 40x and Book E specific ones. I had to make CONFIG_GENERIC_CLOCKEVENTS option selectable for the compatibility reasons

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-05-17 Thread Kumar Gala
On May 17, 2007, at 12:42 PM, Sergei Shtylyov wrote: Add PowerPC decrementer clock event driver. Every effort has been made to support the different implementations of the decrementer: the classic one (with 970 series variation), 40x and Book E specific ones. I had to make

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-05-17 Thread Sergei Shtylyov
Hello. Kumar Gala wrote: Index: linux-2.6/arch/powerpc/kernel/time.c === --- linux-2.6.orig/arch/powerpc/kernel/time.c +++ linux-2.6/arch/powerpc/kernel/time.c [...] @@ -128,6 +129,83 @@ unsigned long ppc_tb_freq; static u64

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-05-17 Thread Kumar Gala
On May 17, 2007, at 1:07 PM, Sergei Shtylyov wrote: Hello. Kumar Gala wrote: Index: linux-2.6/arch/powerpc/kernel/time.c === --- linux-2.6.orig/arch/powerpc/kernel/time.c +++ linux-2.6/arch/powerpc/kernel/time.c [...] @@

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-05-17 Thread Sergei Shtylyov
Hello. Kumar Gala wrote: I haven't looked at all the new clock/timer code, is there any utility in having support for more than one clock source? Of course, you may register as many as you like. - k WBR, Sergei - To unsubscribe from this list: send the line unsubscribe linux-kernel

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-05-17 Thread Kumar Gala
On May 17, 2007, at 1:26 PM, Sergei Shtylyov wrote: Hello. Kumar Gala wrote: I haven't looked at all the new clock/timer code, is there any utility in having support for more than one clock source? Of course, you may register as many as you like. Sure, but is there any utility in

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-05-17 Thread Sergei Shtylyov
Hello. Kumar Gala wrote: Kumar Gala wrote: I haven't looked at all the new clock/timer code, is there any utility in having support for more than one clock source? Of course, you may register as many as you like. Sure, but is there any utility in registering more than the

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-05-17 Thread Segher Boessenkool
+* We must write a positive value to the decrementer to clear +* the interrupt on the IBM 970 CPU series. In periodic mode, +* this happens when the decrementer gets reloaded later, but +* in one-shot mode, we have to do it here since an event handler +*

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-05-17 Thread Sergei Shtylyov
Segher Boessenkool wrote: + * We must write a positive value to the decrementer to clear + * the interrupt on the IBM 970 CPU series. In periodic mode, + * this happens when the decrementer gets reloaded later, but + * in one-shot mode, we have to do it here since an event

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-05-17 Thread Segher Boessenkool
+ * We must write a positive value to the decrementer to clear + * the interrupt on the IBM 970 CPU series. In periodic mode, + * this happens when the decrementer gets reloaded later, but + * in one-shot mode, we have to do it here since an event handler + * may skip

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-05-17 Thread Sergei Shtylyov
Segher Boessenkool wrote: + * We must write a positive value to the decrementer to clear + * the interrupt on the IBM 970 CPU series. In periodic mode, + * this happens when the decrementer gets reloaded later, but + * in one-shot mode, we have to do it here since an event

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-05-17 Thread Segher Boessenkool
Otherwise, when the contents of DEC0 change, the exception effects of the Decrementer become consistent with the new contents of the Decrementer reasonably soon after the change. And that is guaranteed on all PowerPC as far as I can see. The main thing is that a decrementer exception won't go

Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

2007-05-17 Thread Albert Cahalan
Sergei Shtylyov writes: Kumar Gala wrote: [Sergei Shtylyov] Kumar Gala wrote: I haven't looked at all the new clock/timer code, is there any utility in having support for more than one clock source? Of course, you may register as many as you like. Sure, but is there any utility in

  1   2   >