| Message ID | 1341316788-12730-1-git-send-email-lee.jones@linaro.org (mailing list archive) |
|---|---|
| State | New, archived |
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On Tue, Jul 03, 2012 at 12:59:48PM +0100, Lee Jones wrote: > We register the ab8500 as an MFD device from db8500 code during Device Tree > boot in order to solve some limitations of DT. However, when Device Tree is > not enabled, we still want to allow platform code to register the ab8500 in > the normal way. Here we force MFD device registration of the ab8500 only > when booting with Device Tree enabled. > > Solves this issue: > WARNING: at fs/sysfs/dir.c:526 sysfs_add_one+0x88/0xb0() > sysfs: cannot create duplicate filename '/bus/platform/devices/ab8500-core.0' Do we really want to create MFD cells like this (which are really Linux internal things and might vary if another OS or another version of Linux changes its internal abstractions) from the device tree?
On 03/07/12 13:35, Mark Brown wrote: > On Tue, Jul 03, 2012 at 12:59:48PM +0100, Lee Jones wrote: >> We register the ab8500 as an MFD device from db8500 code during Device Tree >> boot in order to solve some limitations of DT. However, when Device Tree is >> not enabled, we still want to allow platform code to register the ab8500 in >> the normal way. Here we force MFD device registration of the ab8500 only >> when booting with Device Tree enabled. >> >> Solves this issue: >> WARNING: at fs/sysfs/dir.c:526 sysfs_add_one+0x88/0xb0() >> sysfs: cannot create duplicate filename '/bus/platform/devices/ab8500-core.0' > > Do we really want to create MFD cells like this (which are really Linux > internal things and might vary if another OS or another version of Linux > changes its internal abstractions) from the device tree? We're not creating them. We're merely using current infrastructure. Before, when we probed each device from Device Tree we came up against some fairly major limitations of the Device Tree. As a result, Arnd and I agreed that this was the way to go. See c5395e7ed8f16cc7bb72a783de68659db5aed515 for a short description of the troubles we faced.
On Tue, Jul 03, 2012 at 02:07:45PM +0100, Lee Jones wrote: > On 03/07/12 13:35, Mark Brown wrote: > >Do we really want to create MFD cells like this (which are really Linux > >internal things and might vary if another OS or another version of Linux > >changes its internal abstractions) from the device tree? > We're not creating them. We're merely using current infrastructure. *Very* recently added infrastructure which caused you to notice this... > Before, when we probed each device from Device Tree we came up > against some fairly major limitations of the Device Tree. As a > result, Arnd and I agreed that this was the way to go. I'm really unconvinced that instnatiating the MFD cells from device tree is in general a good idea. > See c5395e7ed8f16cc7bb72a783de68659db5aed515 for a short description > of the troubles we faced. $ git show c5395e7ed8f16cc7bb72a783de68659db5aed515 fatal: bad object c5395e7ed8f16cc7bb72a783de68659db5aed515
On 03/07/12 14:24, Mark Brown wrote: > On Tue, Jul 03, 2012 at 02:07:45PM +0100, Lee Jones wrote: >> On 03/07/12 13:35, Mark Brown wrote: > >>> Do we really want to create MFD cells like this (which are really Linux >>> internal things and might vary if another OS or another version of Linux >>> changes its internal abstractions) from the device tree? > >> We're not creating them. We're merely using current infrastructure. > > *Very* recently added infrastructure which caused you to notice this... No, I mean the MFD method is current infrastructure. Using it with DT is new, yes. >> Before, when we probed each device from Device Tree we came up >> against some fairly major limitations of the Device Tree. As a >> result, Arnd and I agreed that this was the way to go. > > I'm really unconvinced that instnatiating the MFD cells from device tree > is in general a good idea. Well it just doesn't work the other way. >> See c5395e7ed8f16cc7bb72a783de68659db5aed515 for a short description >> of the troubles we faced. > > $ git show c5395e7ed8f16cc7bb72a783de68659db5aed515 > fatal: bad object c5395e7ed8f16cc7bb72a783de68659db5aed515 Sorry, looks live I've rebased since. 5f3fc8adeec9bb12742fbfa777fa1947deda21a2
On Tuesday 03 July 2012, Mark Brown wrote: > > Before, when we probed each device from Device Tree we came up > > against some fairly major limitations of the Device Tree. As a > > result, Arnd and I agreed that this was the way to go. > > I'm really unconvinced that instnatiating the MFD cells from device tree > is in general a good idea. In general it's not, e.g. it makes no sense when the MFD is just a bunch of registers that are mapped to various distinct Linux devices. The two mfd devices on ux500 (prcmu and ab8500) are really buses by themselves that happen to be implemented using the MFD framework on Linux. I don't see how we would get around representing the buses in the device tree because we have to refer to nodes under them from off-chip devices. Simplified we have something like db9500 { prcmu { opp@1 { }; regulator@2 { }; watchdog@4 { }; ab8500@5 { regulator@3 { }; regulator@4 { }; adc@a { }; rtc@f { }; irq@e { }; gpio@10 { }; }; }; }; Most of the stuff on the board is connected to the ab8500 regulators and gpio pins, which are also used as interrupts. In order to hook up the external devices in the device tree, we need to have something that we can point to as their interrupt-parent or the phandle in the gpio description. Arnd
On Tue, Jul 03, 2012 at 02:48:29PM +0100, Lee Jones wrote: > On 03/07/12 14:24, Mark Brown wrote: > >I'm really unconvinced that instnatiating the MFD cells from device tree > >is in general a good idea. > Well it just doesn't work the other way. In what way does it not work? > >>See c5395e7ed8f16cc7bb72a783de68659db5aed515 for a short description > >>of the troubles we faced. > >$ git show c5395e7ed8f16cc7bb72a783de68659db5aed515 > >fatal: bad object c5395e7ed8f16cc7bb72a783de68659db5aed515 > Sorry, looks live I've rebased since. > 5f3fc8adeec9bb12742fbfa777fa1947deda21a2 This doesn't explain any of the issues, it just says that they exist. My best guess would be that at least some of the issue is due to instantiating the MFD cells from the device tree but it's hard to say clearly.
On Tue, Jul 03, 2012 at 02:01:35PM +0000, Arnd Bergmann wrote: > On Tuesday 03 July 2012, Mark Brown wrote: > > I'm really unconvinced that instnatiating the MFD cells from device tree > > is in general a good idea. > In general it's not, e.g. it makes no sense when the MFD is just > a bunch of registers that are mapped to various distinct Linux > devices. The two mfd devices on ux500 (prcmu and ab8500) are really > buses by themselves that happen to be implemented using the MFD > framework on Linux. This is true for pretty much all MFDs except the pure MMIO ones. > I don't see how we would get around representing the buses in > the device tree because we have to refer to nodes under them > from off-chip devices. Simplified we have something like We can always refer to the parent device itself; there's two separate things going on here which we can resolve separately. One is instantiating the children and the other is referencing the various configuration that's needed which we don't need to do by mapping MFD cells directly onto device tree nodes. The MFD children can always look at the DT bindings of their parents. > Most of the stuff on the board is connected to the ab8500 regulators and > gpio pins, which are also used as interrupts. In order to hook up > the external devices in the device tree, we need to have something that > we can point to as their interrupt-parent or the phandle in the gpio > description. Right, but there's no reason we have to instantiate a dedicated node for each of these things and we should think carefully about what we're doing. One of the problems I've seen with people doing this stuff is that the split we do for some of the cells in Linux is often not really a good generic representation of the hardware (and some of them are actually churning right now) so encoding it in the device tree isn't so helpful. You also seem to get stuff where the MFD cells are all full of hard coding for their parent so there's no way you could reuse them and again we don't gain anything. There will be some places where representing things directly in the DT makes sense but we should think carefully before we go and do it.
Hi Sam, On 03/07/12 12:59, Lee Jones wrote: > We register the ab8500 as an MFD device from db8500 code during Device Tree > boot in order to solve some limitations of DT. However, when Device Tree is > not enabled, we still want to allow platform code to register the ab8500 in > the normal way. Here we force MFD device registration of the ab8500 only > when booting with Device Tree enabled. > > Solves this issue: > WARNING: at fs/sysfs/dir.c:526 sysfs_add_one+0x88/0xb0() > sysfs: cannot create duplicate filename '/bus/platform/devices/ab8500-core.0' > > Reported-by: Linus Walleij <linus.walleij@linaro.org> > Signed-off-by: Lee Jones <lee.jones@linaro.org> Are you planning on taking this in any time soon? I'd really like to fix this bug for Linus in -next. Kind regards, Lee
On 03/07/12 15:21, Mark Brown wrote: > On Tue, Jul 03, 2012 at 02:48:29PM +0100, Lee Jones wrote: >> On 03/07/12 14:24, Mark Brown wrote: > >>> I'm really unconvinced that instnatiating the MFD cells from device tree >>> is in general a good idea. > >> Well it just doesn't work the other way. > > In what way does it not work? > >>>> See c5395e7ed8f16cc7bb72a783de68659db5aed515 for a short description >>>> of the troubles we faced. > >>> $ git show c5395e7ed8f16cc7bb72a783de68659db5aed515 >>> fatal: bad object c5395e7ed8f16cc7bb72a783de68659db5aed515 > >> Sorry, looks live I've rebased since. > >> 5f3fc8adeec9bb12742fbfa777fa1947deda21a2 > > This doesn't explain any of the issues, it just says that they exist. > My best guess would be that at least some of the issue is due to > instantiating the MFD cells from the device tree but it's hard to say > clearly. I'm guessing Arnd's email answered some of the questions you had. Let me know of you would like me to explain it in any greater detail. By the way, this patch has nothing to do with registering these devices when DT is enabled. The code already does that. This is a bug fix, to stop multiple registration of the ab8500 when DT is _not_ enabled.
On Thu, Jul 05, 2012 at 08:36:38AM +0100, Lee Jones wrote: > On 03/07/12 15:21, Mark Brown wrote: > >This doesn't explain any of the issues, it just says that they exist. > >My best guess would be that at least some of the issue is due to > >instantiating the MFD cells from the device tree but it's hard to say > >clearly. > I'm guessing Arnd's email answered some of the questions you had. > Let me know of you would like me to explain it in any greater > detail. No, frankly. It was just a general "why might we put things in DT" answer which (especially given what you say below) isn't related to the issue at all. > By the way, this patch has nothing to do with registering these > devices when DT is enabled. The code already does that. This is a > bug fix, to stop multiple registration of the ab8500 when DT is > _not_ enabled. Really? It seems really surprising that adding more DT support to the MFD core would have any bearing on something like this...
On 05/07/12 10:45, Mark Brown wrote: > On Thu, Jul 05, 2012 at 08:36:38AM +0100, Lee Jones wrote: >> On 03/07/12 15:21, Mark Brown wrote: > >>> This doesn't explain any of the issues, it just says that they exist. >>> My best guess would be that at least some of the issue is due to >>> instantiating the MFD cells from the device tree but it's hard to say >>> clearly. > >> I'm guessing Arnd's email answered some of the questions you had. >> Let me know of you would like me to explain it in any greater >> detail. > > No, frankly. It was just a general "why might we put things in DT" > answer which (especially given what you say below) isn't related to the > issue at all. Okay, so currently we have something like this: / { soc-u9500 { #address-cells = <1>; #size-cells = <1>; ranges; /* * The nodes below which have addresses associated with * them all have correctly formed reg properties: * i.e. "reg = <0xa0411000 0x1000>" */ intc: interrupt-controller@a0411000 L2: l2-cache pmu timer@a0410600 rtc@80154000 gpio0: gpio@8012e000 pinctrl usb@a03e0000 dma-controller@801C0000 /* * Then it becomes more interesting. We have the PRCMU * which has the same address space as above, but its * children have mixed address spaces. Some have their * own set of memory mapped registers, others are * communicated with by i2c. So: */ prcmu@80157000 { reg = <0x80157000 0x1000>; #address-cells = <1>; #size-cells = <1>; ranges; /* The timer has its own memory mapped address space. */ prcmu-timer-4@80157450 /* Ignore the regulators, no one really cares about those ;) */ db8500-prcmu-regulators /* * Then the ab8500 communicates with the PRCMU via a selection * of i2c mailboxes. So we did have this: * mailbox { * #address-cells = <1>; * #size-cells = <0>; * * ab8500 { <blah> }; * } * But then Device Tree complains at you because of this: drivers/of/address.c: > #define OF_CHECK_COUNTS(na, ns) ((na) > 0 && (na) <= OF_MAX_ADDR_CELLS && (ns) > 0) > > /* Cound address cells & copy address locally */ > bus->count_cells(dev, &na, &ns); > if (!OF_CHECK_COUNTS(na, ns)) { > printk(KERN_ERR "prom_parse: Bad cell count for %s\n", > dev->full_name); > goto bail; > } * Device Tree doesn't allow you to have zero size cells, * which we would require if we were to register all of the * AB8500 devices separately during a DT boot. */ ab8500@5 { reg = <5>; /* mailbox 5 is i2c */ ab8500-rtc ab8500-gpadc ab8500-usb reg = <1>; ab8500-ponkey ab8500-sysctrl ab8500-pwm ab8500-debugfs ab8500-regulators }; }; i2c@80004000 ssp@80002000 uart@80120000 sdi@80126000 external-bus@50000000 }; }; Besides, the main role of Device Tree is to eradicate platform code. Whereas the code in the MFD driver used to register the AB8500 devices is not platform code. Does that answer your question better? >> By the way, this patch has nothing to do with registering these >> devices when DT is enabled. The code already does that. This is a >> bug fix, to stop multiple registration of the ab8500 when DT is >> _not_ enabled. > > Really? It seems really surprising that adding more DT support to the > MFD core would have any bearing on something like this... I'm not really sure what you mean by this.
On Thu, Jul 05, 2012 at 12:46:49PM +0100, Lee Jones wrote: > Besides, the main role of Device Tree is to eradicate platform code. > Whereas the code in the MFD driver used to register the AB8500 devices > is not platform code. Right, this is a big part of what I'm saying. > Does that answer your question better? Not really, no. > >> By the way, this patch has nothing to do with registering these > >> devices when DT is enabled. The code already does that. This is a > >> bug fix, to stop multiple registration of the ab8500 when DT is > >> _not_ enabled. > > Really? It seems really surprising that adding more DT support to the > > MFD core would have any bearing on something like this... > I'm not really sure what you mean by this. You seemed to be suggesting that your fix was in some way related to the DT changes in the MFD core. I'm unsure as to the relationship here.
On 05/07/12 13:06, Mark Brown wrote: > On Thu, Jul 05, 2012 at 12:46:49PM +0100, Lee Jones wrote: > >> Besides, the main role of Device Tree is to eradicate platform code. >> Whereas the code in the MFD driver used to register the AB8500 devices >> is not platform code. > > Right, this is a big part of what I'm saying. > >> Does that answer your question better? > > Not really, no. Then you're not asking the right question. :) >>>> By the way, this patch has nothing to do with registering these >>>> devices when DT is enabled. The code already does that. This is a >>>> bug fix, to stop multiple registration of the ab8500 when DT is >>>> _not_ enabled. > >>> Really? It seems really surprising that adding more DT support to the >>> MFD core would have any bearing on something like this... > >> I'm not really sure what you mean by this. > > You seemed to be suggesting that your fix was in some way related to the > DT changes in the MFD core. I'm unsure as to the relationship here. How is it not related? In English the patch would say; "Only register the AB8500 via the MFD API when we're booting with Device Tree. This allows AB8500 related devices to be registered in the normal way, rather than registering them individually using DT and prevents duplicate registration when we are not executing a Device Tree enabled boot."
On Thu, Jul 05, 2012 at 01:15:45PM +0100, Lee Jones wrote: > On 05/07/12 13:06, Mark Brown wrote: > >You seemed to be suggesting that your fix was in some way related to the > >DT changes in the MFD core. I'm unsure as to the relationship here. > How is it not related? In English the patch would say; "Only > register the AB8500 via the MFD API when we're booting with Device > Tree. This allows AB8500 related devices to be registered in the > normal way, rather than registering them individually using DT and > prevents duplicate registration when we are not executing a Device > Tree enabled boot." This is what you said before and it still doesn't make much sense to me. I'd expect that if anything your first statement would be the opposite of what happens - it seems like your non-DT code is doing something really odd. If anything I'd expect adding a DT to add duplicate registrations, I'd not expect it to remove registrations. What I'd expect is that if we can figure out that we need to register the AB8500 automatically without any information from DT then we should be able to figure out exactly the same thing in the non-DT case. I would therefore expect that the change would instead be something which removes the other source of registrations.
On 05/07/12 13:29, Mark Brown wrote: > On Thu, Jul 05, 2012 at 01:15:45PM +0100, Lee Jones wrote: >> On 05/07/12 13:06, Mark Brown wrote: > >>> You seemed to be suggesting that your fix was in some way related to the >>> DT changes in the MFD core. I'm unsure as to the relationship here. > >> How is it not related? In English the patch would say; "Only >> register the AB8500 via the MFD API when we're booting with Device >> Tree. This allows AB8500 related devices to be registered in the >> normal way, rather than registering them individually using DT and >> prevents duplicate registration when we are not executing a Device >> Tree enabled boot." > > This is what you said before and it still doesn't make much sense to me. > I'd expect that if anything your first statement would be the opposite > of what happens - it seems like your non-DT code is doing something > really odd. If anything I'd expect adding a DT to add duplicate > registrations, I'd not expect it to remove registrations. > > What I'd expect is that if we can figure out that we need to register > the AB8500 automatically without any information from DT then we should > be able to figure out exactly the same thing in the non-DT case. I > would therefore expect that the change would instead be something which > removes the other source of registrations. Now you're confusing me. :) If DT is _not_ enabled, we do: From platform code: - Register the DB8500-PRCMU - Register the AB8500 So you see the registration is separate. If DT _is_ enabled, we do: From Device Tree: - Register the DB8500-PRCMU (which in turn registers the AB8500) In this case we the DB8500-PRCMU goes on to register the AB8500 for us, so we need to ensure DT _is_ running before we go on to do that, because if we don't the DB8500-PRCMU will register it and so will platform code.
On Thu, Jul 05, 2012 at 01:41:12PM +0100, Lee Jones wrote: > On 05/07/12 13:29, Mark Brown wrote: > If DT is _not_ enabled, we do: > From platform code: > - Register the DB8500-PRCMU > - Register the AB8500 > So you see the registration is separate. Right, so what I'm saying is that what I'd expect unless there's something unusual going on is that you wouldn't be doing the separate registration of the AB8500 here and would instead be passing the platform data for the AB8500 through in the same way you pass the DT data through. DT and non-DT do have a very similar model for this stuff.
On 05/07/12 13:45, Mark Brown wrote: > On Thu, Jul 05, 2012 at 01:41:12PM +0100, Lee Jones wrote: >> On 05/07/12 13:29, Mark Brown wrote: > >> If DT is _not_ enabled, we do: > >> From platform code: >> - Register the DB8500-PRCMU >> - Register the AB8500 > >> So you see the registration is separate. > > Right, so what I'm saying is that what I'd expect unless there's > something unusual going on is that you wouldn't be doing the separate > registration of the AB8500 here and would instead be passing the > platform data for the AB8500 through in the same way you pass the DT > data through. Then were would you register it, if not here? > DT and non-DT do have a very similar model for this stuff.
On Thu, Jul 05, 2012 at 01:55:50PM +0100, Lee Jones wrote: > On 05/07/12 13:45, Mark Brown wrote: > >Right, so what I'm saying is that what I'd expect unless there's > >something unusual going on is that you wouldn't be doing the separate > >registration of the AB8500 here and would instead be passing the > >platform data for the AB8500 through in the same way you pass the DT > >data through. > Then were would you register it, if not here? Same place as for DT.
Hi Lee, On Tue, Jul 3, 2012 at 8:59 AM, Lee Jones <lee.jones@linaro.org> wrote: > We register the ab8500 as an MFD device from db8500 code during Device Tree > boot in order to solve some limitations of DT. However, when Device Tree is > not enabled, we still want to allow platform code to register the ab8500 in > the normal way. Here we force MFD device registration of the ab8500 only > when booting with Device Tree enabled. > > Solves this issue: > WARNING: at fs/sysfs/dir.c:526 sysfs_add_one+0x88/0xb0() > sysfs: cannot create duplicate filename '/bus/platform/devices/ab8500-core.0' Does the following patch fix your issue? http://www.spinics.net/lists/arm-kernel/msg182827.html Regards, Fabio Estevam
On 05/07/12 14:03, Mark Brown wrote: > On Thu, Jul 05, 2012 at 01:55:50PM +0100, Lee Jones wrote: >> On 05/07/12 13:45, Mark Brown wrote: > >>> Right, so what I'm saying is that what I'd expect unless there's >>> something unusual going on is that you wouldn't be doing the separate >>> registration of the AB8500 here and would instead be passing the >>> platform data for the AB8500 through in the same way you pass the DT >>> data through. > >> Then were would you register it, if not here? > > Same place as for DT. That is a possibility, but the idea is to reduce code in the platform area, not add to it. We'd also need a completely separate platform_data structure to the one we use for platform registration, as much of it has now been moved into Device Tree. The regulators are a good example of this, but there's also GPIO information which is no longer relevant etc. I do believe that registering the AB8500 from the DB8500 is appropriate though, for the simple reason that the AB8500 is a sub-device to the DB8500. I think this is the correct thing to do. But anyway, as I said before, that ship has sailed. We _already_ do this. All this patch does is prevent the AB8500 from being registered twice when DT is not enabled.
Hi Fabio, > On Tue, Jul 3, 2012 at 8:59 AM, Lee Jones <lee.jones@linaro.org> wrote: >> We register the ab8500 as an MFD device from db8500 code during Device Tree >> boot in order to solve some limitations of DT. However, when Device Tree is >> not enabled, we still want to allow platform code to register the ab8500 in >> the normal way. Here we force MFD device registration of the ab8500 only >> when booting with Device Tree enabled. >> >> Solves this issue: >> WARNING: at fs/sysfs/dir.c:526 sysfs_add_one+0x88/0xb0() >> sysfs: cannot create duplicate filename '/bus/platform/devices/ab8500-core.0' > > Does the following patch fix your issue? > http://www.spinics.net/lists/arm-kernel/msg182827.html No, it's unrelated.
On Thu, Jul 05, 2012 at 02:12:09PM +0100, Lee Jones wrote: > On 05/07/12 14:03, Mark Brown wrote: > >On Thu, Jul 05, 2012 at 01:55:50PM +0100, Lee Jones wrote: > >>Then were would you register it, if not here? > >Same place as for DT. > That is a possibility, but the idea is to reduce code in the > platform area, not add to it. We'd also need a completely separate But surely this would, if anything, remove code? You already have the code to do the registration in the MFD so all you're going to be doing here is removing the code from > platform_data structure to the one we use for platform registration, > as much of it has now been moved into Device Tree. The regulators > are a good example of this, but there's also GPIO information which > is no longer relevant etc. Hrm, the usual pattern for this stuff is that the DT is parsed into platform data so the DT code is isolated to the parser. It sounds like you've got a very different structure here? > I do believe that registering the AB8500 from the DB8500 is > appropriate though, for the simple reason that the AB8500 is a > sub-device to the DB8500. I think this is the correct thing to do. > But anyway, as I said before, that ship has sailed. We _already_ do > this. All this patch does is prevent the AB8500 from being > registered twice when DT is not enabled. Well, it also introduces code into mainline which is likely to be used as a template by other people - I'd be especially worried about the next ST platform ending up repeating the same mistakes. If the code is so separate perhaps it's better to just remove the non-DT support?
On 05/07/12 14:20, Mark Brown wrote: > On Thu, Jul 05, 2012 at 02:12:09PM +0100, Lee Jones wrote: >> On 05/07/12 14:03, Mark Brown wrote: >>> On Thu, Jul 05, 2012 at 01:55:50PM +0100, Lee Jones wrote: > >>>> Then were would you register it, if not here? > >>> Same place as for DT. > >> That is a possibility, but the idea is to reduce code in the >> platform area, not add to it. We'd also need a completely separate > > But surely this would, if anything, remove code? You already have the > code to do the registration in the MFD so all you're going to be doing > here is removing the code from No, it will add platform code if we were to register the ab8500 from the platform area. >> platform_data structure to the one we use for platform registration, >> as much of it has now been moved into Device Tree. The regulators >> are a good example of this, but there's also GPIO information which >> is no longer relevant etc. > > Hrm, the usual pattern for this stuff is that the DT is parsed into > platform data so the DT code is isolated to the parser. It sounds like > you've got a very different structure here? Yes we do. Ref that commit ID I sent you you a few days ago: 5f3fc8adeec9bb12742fbfa777fa1947deda21a2 >> I do believe that registering the AB8500 from the DB8500 is >> appropriate though, for the simple reason that the AB8500 is a >> sub-device to the DB8500. I think this is the correct thing to do. >> But anyway, as I said before, that ship has sailed. We _already_ do >> this. All this patch does is prevent the AB8500 from being >> registered twice when DT is not enabled. > > Well, it also introduces code into mainline which is likely to be used > as a template by other people - I'd be especially worried about the next > ST platform ending up repeating the same mistakes. There are no mistakes. It would work for other platforms. :) > If the code is so > separate perhaps it's better to just remove the non-DT support? That's the plan.
On Thu, Jul 05, 2012 at 02:54:04PM +0100, Lee Jones wrote: > On 05/07/12 14:20, Mark Brown wrote: [Moving registration to the MFD] > >But surely this would, if anything, remove code? You already have the > >code to do the registration in the MFD so all you're going to be doing > >here is removing the code from > No, it will add platform code if we were to register the ab8500 from > the platform area. Why would this be the case? You've already got registration code in there for use in DT... > >Hrm, the usual pattern for this stuff is that the DT is parsed into > >platform data so the DT code is isolated to the parser. It sounds like > >you've got a very different structure here? > Yes we do. Ref that commit ID I sent you you a few days ago: > 5f3fc8adeec9bb12742fbfa777fa1947deda21a2 This doesn't appear to reference the platform data? > >Well, it also introduces code into mainline which is likely to be used > >as a template by other people - I'd be especially worried about the next > >ST platform ending up repeating the same mistakes. > There are no mistakes. It would work for other platforms. :) Working and good idea aren't the same thing!
Hi Lee, On Thu, Jul 05, 2012 at 02:12:09PM +0100, Lee Jones wrote: > On 05/07/12 14:03, Mark Brown wrote: > >On Thu, Jul 05, 2012 at 01:55:50PM +0100, Lee Jones wrote: > >>On 05/07/12 13:45, Mark Brown wrote: > > > >>>Right, so what I'm saying is that what I'd expect unless there's > >>>something unusual going on is that you wouldn't be doing the separate > >>>registration of the AB8500 here and would instead be passing the > >>>platform data for the AB8500 through in the same way you pass the DT > >>>data through. > > > >>Then were would you register it, if not here? > > > >Same place as for DT. > > That is a possibility, but the idea is to reduce code in the > platform area, not add to it. We'd also need a completely separate > platform_data structure to the one we use for platform registration, > as much of it has now been moved into Device Tree. The regulators > are a good example of this, but there's also GPIO information which > is no longer relevant etc. > > I do believe that registering the AB8500 from the DB8500 is > appropriate though, for the simple reason that the AB8500 is a > sub-device to the DB8500. I think this is the correct thing to do. I agree with you here, and I thus see no reasons why we should have a different code path for DT and !DT cases. > But anyway, as I said before, that ship has sailed. We _already_ do > this. All this patch does is prevent the AB8500 from being > registered twice when DT is not enabled. Sure, and it does exactly that. But this does look like a workaround rather than an actual fix. And Mark is right about showing the wrong example with this kind of patches for other MFD drivers. I'd prefer seeig the !DT support removed for now until you can find a proper and common solution for both DT and !DT cases. Cheers, Samuel.
diff --git a/drivers/mfd/db8500-prcmu.c b/drivers/mfd/db8500-prcmu.c index 80def6c..4ec0ed1 100644 --- a/drivers/mfd/db8500-prcmu.c +++ b/drivers/mfd/db8500-prcmu.c @@ -2964,6 +2964,9 @@ static struct mfd_cell db8500_prcmu_devs[] = { .name = "cpufreq-u8500", .of_compatible = "stericsson,cpufreq-u8500", }, +}; + +static struct mfd_cell db8500_of_prcmu_devs[] = { { .name = "ab8500-core", .of_compatible = "stericsson,ab8500", @@ -3014,6 +3017,15 @@ static int __devinit db8500_prcmu_probe(struct platform_device *pdev) return err; } + if (np) { + err = mfd_add_devices(&pdev->dev, 0, db8500_of_prcmu_devs, + ARRAY_SIZE(db8500_of_prcmu_devs), NULL, 0); + if (err) { + pr_err("prcmu: Failed to add DT subdevices\n"); + return err; + } + } + pr_info("DB8500 PRCMU initialized\n"); no_irq_return:
We register the ab8500 as an MFD device from db8500 code during Device Tree boot in order to solve some limitations of DT. However, when Device Tree is not enabled, we still want to allow platform code to register the ab8500 in the normal way. Here we force MFD device registration of the ab8500 only when booting with Device Tree enabled. Solves this issue: WARNING: at fs/sysfs/dir.c:526 sysfs_add_one+0x88/0xb0() sysfs: cannot create duplicate filename '/bus/platform/devices/ab8500-core.0' Reported-by: Linus Walleij <linus.walleij@linaro.org> Signed-off-by: Lee Jones <lee.jones@linaro.org> --- drivers/mfd/db8500-prcmu.c | 12 ++++++++++++ 1 file changed, 12 insertions(+)