[QUERY] Number of address translation regions in designware

[QUERY] Number of address translation regions in designware

[Kishon Vijay Abraham I]

Hi,

Currently I see in pcie-designware.c we use only 2 ATU regions. We re-use
INDEX0 for mem outbound and cfg0, and INDEX1 for cfg1 and io. So I'd like to
know if in your platform, do you have only 2 address translation regions? In
DRA7xx we have 16 outbound regions and 4 inbound regions.

Also the same designware IP can be used as a EP also no? Shouldn't we move it
out of drivers/pci/host and allow it to be configured as EP also?

Thanks
Kishon

Re: [QUERY] Number of address translation regions in designware

[Pratyush Anand]

Hi,

On Mon, Oct 21, 2013 at 09:28:17PM +0800, Kishon Vijay Abraham I wrote:
> Hi,
> 
> Currently I see in pcie-designware.c we use only 2 ATU regions. We re-use
> INDEX0 for mem outbound and cfg0, and INDEX1 for cfg1 and io. So I'd like to
> know if in your platform, do you have only 2 address translation regions? In
> DRA7xx we have 16 outbound regions and 4 inbound regions.

I do not know about samsung, Jingoo can confirm. In SPEAr1340 there
are only 2 inbound and outbound viewports, but in SPEAr1310 there are
6. It would be good to modify the driver, to avoid re-use of viewport
whereever possible.

> 
> Also the same designware IP can be used as a EP also no? Shouldn't we move it

Yes same IP can be configured as EP. But..

> out of drivers/pci/host and allow it to be configured as EP also?

Same driver may not be used. (Few of these functions might be reused,
but not whole). Moreover, in my experience  running Linux over an EP
can have only importance of validation/demo. Practical use case will
find a simple firmware more suitable.

Regards
Pratyush

> 
> Thanks
> Kishon
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Re: [QUERY] Number of address translation regions in designware

[Jingoo Han]

On Monday, October 21, 2013 10:28 PM, Kishon Vijay Abraham I wrote:
> 
> Currently I see in pcie-designware.c we use only 2 ATU regions. We re-use
> INDEX0 for mem outbound and cfg0, and INDEX1 for cfg1 and io. So I'd like to
> know if in your platform, do you have only 2 address translation regions? In
> DRA7xx we have 16 outbound regions and 4 inbound regions.

In Exynos, there are only 2 inbound and 2 outbound viewpoints.

> Also the same designware IP can be used as a EP also no? Shouldn't we move it
> out of drivers/pci/host and allow it to be configured as EP also?

Currently, Exynos PCIe IP does not support EP mode.

Best regards,
Jingoo Han

Re: [QUERY] Number of address translation regions in designware

[Kishon Vijay Abraham I]

Hi Pratyush, Jingoo,

On Tuesday 22 October 2013 10:46 AM, Jingoo Han wrote:
> On Monday, October 21, 2013 10:28 PM, Kishon Vijay Abraham I wrote:
>>
>> Currently I see in pcie-designware.c we use only 2 ATU regions. We re-use
>> INDEX0 for mem outbound and cfg0, and INDEX1 for cfg1 and io. So I'd like to
>> know if in your platform, do you have only 2 address translation regions? In
>> DRA7xx we have 16 outbound regions and 4 inbound regions.
> 
> In Exynos, there are only 2 inbound and 2 outbound viewpoints.
> 
>> Also the same designware IP can be used as a EP also no? Shouldn't we move it
>> out of drivers/pci/host and allow it to be configured as EP also?
> 
> Currently, Exynos PCIe IP does not support EP mode.

Thanks for the information. I think we can do some optimization w.r.t address
translation regions. Will post a RFC soon.

One more query.
In dw_pcie_prog_viewport_cfg0/dw_pcie_prog_viewport_cfg1 functions, the *lower
target* is programmed to busdev. Is it for any specific reason?
I mean doing that will leave lot of holes in the PCIe address space.
IIUC, if we don't set that to busdev, consecutive pcie address space will be
used for each function no?

Thanks
Kishon

Re: [QUERY] Number of address translation regions in designware

[Pratyush Anand]

Hi Kishon,

On Tue, Oct 22, 2013 at 10:20:01PM +0800, Kishon Vijay Abraham I wrote:
> Hi Pratyush, Jingoo,
> 
> On Tuesday 22 October 2013 10:46 AM, Jingoo Han wrote:
> > On Monday, October 21, 2013 10:28 PM, Kishon Vijay Abraham I wrote:
> >>
> >> Currently I see in pcie-designware.c we use only 2 ATU regions. We re-use
> >> INDEX0 for mem outbound and cfg0, and INDEX1 for cfg1 and io. So I'd like to
> >> know if in your platform, do you have only 2 address translation regions? In
> >> DRA7xx we have 16 outbound regions and 4 inbound regions.
> > 
> > In Exynos, there are only 2 inbound and 2 outbound viewpoints.
> > 
> >> Also the same designware IP can be used as a EP also no? Shouldn't we move it
> >> out of drivers/pci/host and allow it to be configured as EP also?
> > 
> > Currently, Exynos PCIe IP does not support EP mode.
> 
> Thanks for the information. I think we can do some optimization w.r.t address
> translation regions. Will post a RFC soon.
> 
> One more query.
> In dw_pcie_prog_viewport_cfg0/dw_pcie_prog_viewport_cfg1 functions, the *lower
> target* is programmed to busdev. Is it for any specific reason?
> I mean doing that will leave lot of holes in the PCIe address space.
> IIUC, if we don't set that to busdev, consecutive pcie address space will be
> used for each function no?

Yes, I think even if CX_ATU_MIN_REGION_SIZE is 64KB in any controller,
bus, dev and function number can be used to define target address.

So you are trying to allocate statically a separate viewport for each
function's cfg0 transfer (whereever sufficient number of viewport is
avilable)?

If viewport is programmed dynamically at each cfg transfer, then
whether you use bus and dev only or function also, will it really make
any difference in saving of address space?

Regards
Pratyush

> 
> Thanks
> Kishon

Re: [QUERY] Number of address translation regions in designware

[Kishon Vijay Abraham I]

Hi Pratyush,

On Wednesday 23 October 2013 10:06 AM, Pratyush Anand wrote:
> Hi Kishon,
> 
> On Tue, Oct 22, 2013 at 10:20:01PM +0800, Kishon Vijay Abraham I wrote:
>> Hi Pratyush, Jingoo,
>>
>> On Tuesday 22 October 2013 10:46 AM, Jingoo Han wrote:
>>> On Monday, October 21, 2013 10:28 PM, Kishon Vijay Abraham I wrote:
>>>>
>>>> Currently I see in pcie-designware.c we use only 2 ATU regions. We re-use
>>>> INDEX0 for mem outbound and cfg0, and INDEX1 for cfg1 and io. So I'd like to
>>>> know if in your platform, do you have only 2 address translation regions? In
>>>> DRA7xx we have 16 outbound regions and 4 inbound regions.
>>>
>>> In Exynos, there are only 2 inbound and 2 outbound viewpoints.
>>>
>>>> Also the same designware IP can be used as a EP also no? Shouldn't we move it
>>>> out of drivers/pci/host and allow it to be configured as EP also?
>>>
>>> Currently, Exynos PCIe IP does not support EP mode.
>>
>> Thanks for the information. I think we can do some optimization w.r.t address
>> translation regions. Will post a RFC soon.
>>
>> One more query.
>> In dw_pcie_prog_viewport_cfg0/dw_pcie_prog_viewport_cfg1 functions, the *lower
>> target* is programmed to busdev. Is it for any specific reason?
>> I mean doing that will leave lot of holes in the PCIe address space.
>> IIUC, if we don't set that to busdev, consecutive pcie address space will be
>> used for each function no?
> 
> Yes, I think even if CX_ATU_MIN_REGION_SIZE is 64KB in any controller,
> bus, dev and function number can be used to define target address.

I meant for function 0 the configuration space will be from (0x0 t0 0xfff -
4KB). If we use *busdev* for programming target, for function 1 the
configuration space will start at 0x10000 PCIe address which will leave a small
hole from (0x1000 to 0xffff). I'm not sure if it will have a big impact though.
Also till we haven't exhausted the 64KB space (minimum), we wouldn't be needing
to program a new viewport. That's good enough to accommodate 18 functions for
the number of devices.
> 
> So you are trying to allocate statically a separate viewport for each
> function's cfg0 transfer (whereever sufficient number of viewport is
> avilable)?

Actually in DRA7xx, we face a different problem in that, we can't program the
translation region directly from the ranges. Because while programming the
address translation window, the most significant 4 bits are not used.

For example if you see, the cpu address of memory window starts @ 0x20012000
but while programming the address translation window we have to give 0x00012000.

My dt data looked like this.
ranges = <0x00000800 0 0x20001000 0x20001000 0 0x00001000
	  0x81000000 0 0	  0x20002000 0 0x00010000
	  0x82000000 0 0x20012000 0x20012000 0 0xffee000>;

translation = <(OUTBOUND | INDEX0) CFG0 0x0 0x00001000 0x0000fff 0x0 0x00001000
	       (OUTBOUND | INDEX1) IO   0x0 0x00002000 0x000ffff 0x0 0x00002000
	       (OUTBOUND | INDEX2) MEM  0x0 0x00012000 0xffee000 0x0 0x20012000
>;
(btw that translation is a wip I tried to get pcie working in dra7x).

Since I wanted to do the translation configuration from dt data, I was thinking
whether it is necessary to program the viewport dynamically.

But now I think some sort of dynamic programming would be needed, considering
the limitation on few SoCs.

Thanks
Kishon

> 
> If viewport is programmed dynamically at each cfg transfer, then
> whether you use bus and dev only or function also, will it really make
> any difference in saving of address space?
> 
> Regards
> Pratyush
> 
>>
>> Thanks
>> Kishon

Re: [QUERY] Number of address translation regions in designware

[Pratyush Anand]

+ Marek, Tim, arnd

Hi Kishon,

On Wed, Oct 23, 2013 at 11:45:34PM +0800, Kishon Vijay Abraham I wrote:
> Hi Pratyush,
> 
> On Wednesday 23 October 2013 10:06 AM, Pratyush Anand wrote:
> > Hi Kishon,
> > 
> > On Tue, Oct 22, 2013 at 10:20:01PM +0800, Kishon Vijay Abraham I wrote:
> >> Hi Pratyush, Jingoo,
> >>
> >> On Tuesday 22 October 2013 10:46 AM, Jingoo Han wrote:
> >>> On Monday, October 21, 2013 10:28 PM, Kishon Vijay Abraham I wrote:
> >>>>
> >>>> Currently I see in pcie-designware.c we use only 2 ATU regions. We re-use
> >>>> INDEX0 for mem outbound and cfg0, and INDEX1 for cfg1 and io. So I'd like to
> >>>> know if in your platform, do you have only 2 address translation regions? In
> >>>> DRA7xx we have 16 outbound regions and 4 inbound regions.
> >>>
> >>> In Exynos, there are only 2 inbound and 2 outbound viewpoints.
> >>>
> >>>> Also the same designware IP can be used as a EP also no? Shouldn't we move it
> >>>> out of drivers/pci/host and allow it to be configured as EP also?
> >>>
> >>> Currently, Exynos PCIe IP does not support EP mode.
> >>
> >> Thanks for the information. I think we can do some optimization w.r.t address
> >> translation regions. Will post a RFC soon.
> >>
> >> One more query.
> >> In dw_pcie_prog_viewport_cfg0/dw_pcie_prog_viewport_cfg1 functions, the *lower
> >> target* is programmed to busdev. Is it for any specific reason?
> >> I mean doing that will leave lot of holes in the PCIe address space.
> >> IIUC, if we don't set that to busdev, consecutive pcie address space will be
> >> used for each function no?
> > 
> > Yes, I think even if CX_ATU_MIN_REGION_SIZE is 64KB in any controller,
> > bus, dev and function number can be used to define target address.
> 
> I meant for function 0 the configuration space will be from (0x0 t0 0xfff -
> 4KB). If we use *busdev* for programming target, for function 1 the
> configuration space will start at 0x10000 PCIe address which will leave a small
> hole from (0x1000 to 0xffff). I'm not sure if it will have a big impact though.
> Also till we haven't exhausted the 64KB space (minimum), we wouldn't be needing
> to program a new viewport. That's good enough to accommodate 18 functions for
> the number of devices.

Yes, I agree with you that using *busdev* will create hole and we
should avoid it. More on this at the end.

> > 
> > So you are trying to allocate statically a separate viewport for each
> > function's cfg0 transfer (whereever sufficient number of viewport is
> > avilable)?
> 
> Actually in DRA7xx, we face a different problem in that, we can't program the
> translation region directly from the ranges. Because while programming the
> address translation window, the most significant 4 bits are not used.
> 
> For example if you see, the cpu address of memory window starts @ 0x20012000
> but while programming the address translation window we have to give 0x00012000.
> 
> My dt data looked like this.
> ranges = <0x00000800 0 0x20001000 0x20001000 0 0x00001000
> 	  0x81000000 0 0	  0x20002000 0 0x00010000
> 	  0x82000000 0 0x20012000 0x20012000 0 0xffee000>;
> 
> translation = <(OUTBOUND | INDEX0) CFG0 0x0 0x00001000 0x0000fff 0x0 0x00001000
> 	       (OUTBOUND | INDEX1) IO   0x0 0x00002000 0x000ffff 0x0 0x00002000
> 	       (OUTBOUND | INDEX2) MEM  0x0 0x00012000 0xffee000 0x0 0x20012000
> >;

I too have some doubt here..not very clear.. may be someone more
expert can correct (I keep arnd in cc).... How should be the
translation?
In my opinion, input address of translation should be in "bus address
domain"  ie address what PCIe sees and translated output for memory
transaction should be in "parent bus address domain" ie what CPUs
see. If my understanding is correct, then pcie designware driver needs
fixes at some places.

I am not much used to DT, but if I understood correctly, in your case
parent bus address and bus address are different.

pp->mem_base = bus address  = range.pci_addr = 0x0000000000012000
pp->config.mem_bus_addr = parent bus address = range.cpu_addr = 0x20012000

So, shouldn't your ranges look like this:

ranges = <0x00000800 0 0x00001000 0x20001000 0 0x00001000
 	  0x81000000 0 0	  0x20002000 0 0x00010000
 	  0x82000000 0 0x00012000 0x20012000 0 0xffee000>;

And then I think with the proper designware driver fixes you should be
able to work.

> (btw that translation is a wip I tried to get pcie working in dra7x).
> 
> Since I wanted to do the translation configuration from dt data, I was thinking
> whether it is necessary to program the viewport dynamically.
> 
> But now I think some sort of dynamic programming would be needed, considering
> the limitation on few SoCs.

Yes, some dynamic programming is needed and not sure how to manage in
case of only one outbound viewport. What about following idea:
1. We keep dynamic for cfg and static for others.
2. We use single viewport for cfg0 and cfg1 both. We do not use
separate cfg0/1 base rather use only cfg_base and cfg_size=64K (we
could have done with even 4K, but some controller might have min
viewport size as 64K). As per viewport CR programmed, translated
output will be cfg0 or cfg1.
3. Now if a controller has only one viewport, a warning message is
generated that IO transaction may not work correctly. (I think IO
will always need translation. Just for curiosity anyone knows a ARM
based system which uses PCIe IO transaction?).
4. If a controller has atleast 2 viewport, we program second viewport
statically for IO transaction.
5. If it has only two viewport, and cpu_addr != pci_addr, a warning
message is generated that MEM transaction may not work correctly.
6. Else, 3rd viewport is programmed for mem transaction.

Regards
Pratyush

> 
> Thanks
> Kishon
> 
> > 
> > If viewport is programmed dynamically at each cfg transfer, then
> > whether you use bus and dev only or function also, will it really make
> > any difference in saving of address space?
> > 
> > Regards
> > Pratyush
> > 
> >>
> >> Thanks
> >> Kishon

Re: [QUERY] Number of address translation regions in designware

[Kishon Vijay Abraham I]

Hi Pratyush,

On Tuesday 29 October 2013 12:40 PM, Pratyush Anand wrote:
> + Marek, Tim, arnd
> 
> Hi Kishon,
> 
> On Wed, Oct 23, 2013 at 11:45:34PM +0800, Kishon Vijay Abraham I wrote:
>> Hi Pratyush,
>>
>> On Wednesday 23 October 2013 10:06 AM, Pratyush Anand wrote:
>>> Hi Kishon,
>>>
>>> On Tue, Oct 22, 2013 at 10:20:01PM +0800, Kishon Vijay Abraham I wrote:
>>>> Hi Pratyush, Jingoo,
>>>>
>>>> On Tuesday 22 October 2013 10:46 AM, Jingoo Han wrote:
>>>>> On Monday, October 21, 2013 10:28 PM, Kishon Vijay Abraham I wrote:
>>>>>>
>>>>>> Currently I see in pcie-designware.c we use only 2 ATU regions. We re-use
>>>>>> INDEX0 for mem outbound and cfg0, and INDEX1 for cfg1 and io. So I'd like to
>>>>>> know if in your platform, do you have only 2 address translation regions? In
>>>>>> DRA7xx we have 16 outbound regions and 4 inbound regions.
>>>>>
>>>>> In Exynos, there are only 2 inbound and 2 outbound viewpoints.
>>>>>
>>>>>> Also the same designware IP can be used as a EP also no? Shouldn't we move it
>>>>>> out of drivers/pci/host and allow it to be configured as EP also?
>>>>>
>>>>> Currently, Exynos PCIe IP does not support EP mode.
>>>>
>>>> Thanks for the information. I think we can do some optimization w.r.t address
>>>> translation regions. Will post a RFC soon.
>>>>
>>>> One more query.
>>>> In dw_pcie_prog_viewport_cfg0/dw_pcie_prog_viewport_cfg1 functions, the *lower
>>>> target* is programmed to busdev. Is it for any specific reason?
>>>> I mean doing that will leave lot of holes in the PCIe address space.
>>>> IIUC, if we don't set that to busdev, consecutive pcie address space will be
>>>> used for each function no?
>>>
>>> Yes, I think even if CX_ATU_MIN_REGION_SIZE is 64KB in any controller,
>>> bus, dev and function number can be used to define target address.
>>
>> I meant for function 0 the configuration space will be from (0x0 t0 0xfff -
>> 4KB). If we use *busdev* for programming target, for function 1 the
>> configuration space will start at 0x10000 PCIe address which will leave a small
>> hole from (0x1000 to 0xffff). I'm not sure if it will have a big impact though.
>> Also till we haven't exhausted the 64KB space (minimum), we wouldn't be needing
>> to program a new viewport. That's good enough to accommodate 18 functions for
>> the number of devices.
> 
> Yes, I agree with you that using *busdev* will create hole and we
> should avoid it. More on this at the end.
> 
>>>
>>> So you are trying to allocate statically a separate viewport for each
>>> function's cfg0 transfer (whereever sufficient number of viewport is
>>> avilable)?
>>
>> Actually in DRA7xx, we face a different problem in that, we can't program the
>> translation region directly from the ranges. Because while programming the
>> address translation window, the most significant 4 bits are not used.
>>
>> For example if you see, the cpu address of memory window starts @ 0x20012000
>> but while programming the address translation window we have to give 0x00012000.
>>
>> My dt data looked like this.
>> ranges = <0x00000800 0 0x20001000 0x20001000 0 0x00001000
>> 	  0x81000000 0 0	  0x20002000 0 0x00010000
>> 	  0x82000000 0 0x20012000 0x20012000 0 0xffee000>;
>>
>> translation = <(OUTBOUND | INDEX0) CFG0 0x0 0x00001000 0x0000fff 0x0 0x00001000
>> 	       (OUTBOUND | INDEX1) IO   0x0 0x00002000 0x000ffff 0x0 0x00002000
>> 	       (OUTBOUND | INDEX2) MEM  0x0 0x00012000 0xffee000 0x0 0x20012000
>>> ;
> 
> I too have some doubt here..not very clear.. may be someone more
> expert can correct (I keep arnd in cc).... How should be the
> translation?
> In my opinion, input address of translation should be in "bus address
> domain"  ie address what PCIe sees and translated output for memory

It actually depends on whether we are configuring inbound or outbound. IIUC,
what you just mentioned will be for configuring inbound translation window.

For the outbound translation window, it'll be the other way round. *base* will
be the CPU address and target will be the PCIe address.
> transaction should be in "parent bus address domain" ie what CPUs
> see. If my understanding is correct, then pcie designware driver needs
> fixes at some places.
> 
> I am not much used to DT, but if I understood correctly, in your case
> parent bus address and bus address are different.
> 
> pp->mem_base = bus address  = range.pci_addr = 0x0000000000012000
> pp->config.mem_bus_addr = parent bus address = range.cpu_addr = 0x20012000

Not like that. It's the same.
In DRA7, the cpu sees 32bit address, but the pcie controller can see only 28bit
address. So whenever the cpu issues a read/write request, the 4 most
significant bits are used by L3 to determine the target controller.
For example, the cpu reserves 0x2000_0000 - 0x2FFF_FFFF for PCIe controller but
the PCIe controller will see only (0x000_0000 - 0xFFF_FFF). So for programming
the outbound translation window the *base* should be programmed as 0x000_0000.
Whenever we try to write to say 0x2000_0000, it will be translated to whatever
we have programmed in the translation window with base as 0x000_0000.

Thanks
Kishon

Re: [QUERY] Number of address translation regions in designware

[Pratyush Anand]

On Tue, Oct 29, 2013 at 4:25 PM, Kishon Vijay Abraham I <kishon@ti.com> wrote:
> Hi Pratyush,
>
> On Tuesday 29 October 2013 12:40 PM, Pratyush Anand wrote:
>> + Marek, Tim, arnd
>>
>> Hi Kishon,
>>
>> On Wed, Oct 23, 2013 at 11:45:34PM +0800, Kishon Vijay Abraham I wrote:
>>> Hi Pratyush,
>>>
>>> On Wednesday 23 October 2013 10:06 AM, Pratyush Anand wrote:
>>>> Hi Kishon,
>>>>
>>>> On Tue, Oct 22, 2013 at 10:20:01PM +0800, Kishon Vijay Abraham I wrote:
>>>>> Hi Pratyush, Jingoo,
>>>>>
>>>>> On Tuesday 22 October 2013 10:46 AM, Jingoo Han wrote:
>>>>>> On Monday, October 21, 2013 10:28 PM, Kishon Vijay Abraham I wrote:
>>>>>>>
>>>>>>> Currently I see in pcie-designware.c we use only 2 ATU regions. We re-use
>>>>>>> INDEX0 for mem outbound and cfg0, and INDEX1 for cfg1 and io. So I'd like to
>>>>>>> know if in your platform, do you have only 2 address translation regions? In
>>>>>>> DRA7xx we have 16 outbound regions and 4 inbound regions.
>>>>>>
>>>>>> In Exynos, there are only 2 inbound and 2 outbound viewpoints.
>>>>>>
>>>>>>> Also the same designware IP can be used as a EP also no? Shouldn't we move it
>>>>>>> out of drivers/pci/host and allow it to be configured as EP also?
>>>>>>
>>>>>> Currently, Exynos PCIe IP does not support EP mode.
>>>>>
>>>>> Thanks for the information. I think we can do some optimization w.r.t address
>>>>> translation regions. Will post a RFC soon.
>>>>>
>>>>> One more query.
>>>>> In dw_pcie_prog_viewport_cfg0/dw_pcie_prog_viewport_cfg1 functions, the *lower
>>>>> target* is programmed to busdev. Is it for any specific reason?
>>>>> I mean doing that will leave lot of holes in the PCIe address space.
>>>>> IIUC, if we don't set that to busdev, consecutive pcie address space will be
>>>>> used for each function no?
>>>>
>>>> Yes, I think even if CX_ATU_MIN_REGION_SIZE is 64KB in any controller,
>>>> bus, dev and function number can be used to define target address.
>>>
>>> I meant for function 0 the configuration space will be from (0x0 t0 0xfff -
>>> 4KB). If we use *busdev* for programming target, for function 1 the
>>> configuration space will start at 0x10000 PCIe address which will leave a small
>>> hole from (0x1000 to 0xffff). I'm not sure if it will have a big impact though.
>>> Also till we haven't exhausted the 64KB space (minimum), we wouldn't be needing
>>> to program a new viewport. That's good enough to accommodate 18 functions for
>>> the number of devices.
>>
>> Yes, I agree with you that using *busdev* will create hole and we
>> should avoid it. More on this at the end.
>>
>>>>
>>>> So you are trying to allocate statically a separate viewport for each
>>>> function's cfg0 transfer (whereever sufficient number of viewport is
>>>> avilable)?
>>>
>>> Actually in DRA7xx, we face a different problem in that, we can't program the
>>> translation region directly from the ranges. Because while programming the
>>> address translation window, the most significant 4 bits are not used.
>>>
>>> For example if you see, the cpu address of memory window starts @ 0x20012000
>>> but while programming the address translation window we have to give 0x00012000.
>>>
>>> My dt data looked like this.
>>> ranges = <0x00000800 0 0x20001000 0x20001000 0 0x00001000
>>>        0x81000000 0 0          0x20002000 0 0x00010000
>>>        0x82000000 0 0x20012000 0x20012000 0 0xffee000>;
>>>
>>> translation = <(OUTBOUND | INDEX0) CFG0 0x0 0x00001000 0x0000fff 0x0 0x00001000
>>>             (OUTBOUND | INDEX1) IO   0x0 0x00002000 0x000ffff 0x0 0x00002000
>>>             (OUTBOUND | INDEX2) MEM  0x0 0x00012000 0xffee000 0x0 0x20012000
>>>> ;
>>
>> I too have some doubt here..not very clear.. may be someone more
>> expert can correct (I keep arnd in cc).... How should be the
>> translation?
>> In my opinion, input address of translation should be in "bus address
>> domain"  ie address what PCIe sees and translated output for memory
>
> It actually depends on whether we are configuring inbound or outbound. IIUC,
> what you just mentioned will be for configuring inbound translation window.
>
> For the outbound translation window, it'll be the other way round. *base* will
> be the CPU address and target will be the PCIe address.

Sure? At the the end you say base address is 0x000_0000 (bus address) and not
0x2000_0000 (parent bus address). It contradicts what you say above, no?
>> transaction should be in "parent bus address domain" ie what CPUs
>> see. If my understanding is correct, then pcie designware driver needs
>> fixes at some places.
>>
>> I am not much used to DT, but if I understood correctly, in your case
>> parent bus address and bus address are different.
>>
>> pp->mem_base = bus address  = range.pci_addr = 0x0000000000012000
>> pp->config.mem_bus_addr = parent bus address = range.cpu_addr = 0x20012000
>
> Not like that. It's the same.
> In DRA7, the cpu sees 32bit address, but the pcie controller can see only 28bit
> address. So whenever the cpu issues a read/write request, the 4 most
> significant bits are used by L3 to determine the target controller.
> For example, the cpu reserves 0x2000_0000 - 0x2FFF_FFFF for PCIe controller but
> the PCIe controller will see only (0x000_0000 - 0xFFF_FFF). So for programming
> the outbound translation window the *base* should be programmed as 0x000_0000.
> Whenever we try to write to say 0x2000_0000, it will be translated to whatever
> we have programmed in the translation window with base as 0x000_0000.

What you say here is also my understanding.
Only question then remains, what should be translated address? All
translated address must lie in the address range programmed in EP's
BAR, then only EP will able to receive that mem transaction, no?
All EP's BAR address will lie in the range of pp->mem.start and
pp->mem.end, am I correct here?
And, pp->mem.start is range.cpu_addr, therefore I said that if target address
is programmed as cpu_address, it should work fine.

Regards
Pratyush

>
> Thanks
> Kishon
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Re: [QUERY] Number of address translation regions in designware

[Marek Vasut]

Hi,

> + Marek, Tim, arnd
> 
> Hi Kishon,
> 
> On Wed, Oct 23, 2013 at 11:45:34PM +0800, Kishon Vijay Abraham I wrote:
> > Hi Pratyush,
> > 
> > On Wednesday 23 October 2013 10:06 AM, Pratyush Anand wrote:
> > > Hi Kishon,
> > > 
> > > On Tue, Oct 22, 2013 at 10:20:01PM +0800, Kishon Vijay Abraham I wrote:
> > >> Hi Pratyush, Jingoo,
> > >> 
> > >> On Tuesday 22 October 2013 10:46 AM, Jingoo Han wrote:
> > >>> On Monday, October 21, 2013 10:28 PM, Kishon Vijay Abraham I wrote:
> > >>>> Currently I see in pcie-designware.c we use only 2 ATU regions. We
> > >>>> re-use INDEX0 for mem outbound and cfg0, and INDEX1 for cfg1 and
> > >>>> io. So I'd like to know if in your platform, do you have only 2
> > >>>> address translation regions? In DRA7xx we have 16 outbound regions
> > >>>> and 4 inbound regions.
> > >>> 
> > >>> In Exynos, there are only 2 inbound and 2 outbound viewpoints.

Jumping in a tad late, MX6 has 4 inbound and 4 outbound according to MX6DQRM 
Rev. 1, 04/2013 sections:
- 48.3.9.1.1 (bullet 8)
- 48.3.9.1.2 (bullet 7)
- 48.10.42 (Region_Index description in the table PCIE_PL_iATUVR)

Best regards,
Marek Vasut

Re: [QUERY] Number of address translation regions in designware

[Kishon Vijay Abraham I]

Hi,

On Tuesday 29 October 2013 09:44 PM, Pratyush Anand wrote:
> On Tue, Oct 29, 2013 at 4:25 PM, Kishon Vijay Abraham I <kishon@ti.com> wrote:
>> Hi Pratyush,
>>
>> On Tuesday 29 October 2013 12:40 PM, Pratyush Anand wrote:
>>> + Marek, Tim, arnd
>>>
>>> Hi Kishon,
>>>
>>> On Wed, Oct 23, 2013 at 11:45:34PM +0800, Kishon Vijay Abraham I wrote:
>>>> Hi Pratyush,
>>>>
>>>> On Wednesday 23 October 2013 10:06 AM, Pratyush Anand wrote:
>>>>> Hi Kishon,
>>>>>
>>>>> On Tue, Oct 22, 2013 at 10:20:01PM +0800, Kishon Vijay Abraham I wrote:
>>>>>> Hi Pratyush, Jingoo,
>>>>>>
>>>>>> On Tuesday 22 October 2013 10:46 AM, Jingoo Han wrote:
>>>>>>> On Monday, October 21, 2013 10:28 PM, Kishon Vijay Abraham I wrote:
>>>>>>>>
>>>>>>>> Currently I see in pcie-designware.c we use only 2 ATU regions. We re-use
>>>>>>>> INDEX0 for mem outbound and cfg0, and INDEX1 for cfg1 and io. So I'd like to
>>>>>>>> know if in your platform, do you have only 2 address translation regions? In
>>>>>>>> DRA7xx we have 16 outbound regions and 4 inbound regions.
>>>>>>>
>>>>>>> In Exynos, there are only 2 inbound and 2 outbound viewpoints.
>>>>>>>
>>>>>>>> Also the same designware IP can be used as a EP also no? Shouldn't we move it
>>>>>>>> out of drivers/pci/host and allow it to be configured as EP also?
>>>>>>>
>>>>>>> Currently, Exynos PCIe IP does not support EP mode.
>>>>>>
>>>>>> Thanks for the information. I think we can do some optimization w.r.t address
>>>>>> translation regions. Will post a RFC soon.
>>>>>>
>>>>>> One more query.
>>>>>> In dw_pcie_prog_viewport_cfg0/dw_pcie_prog_viewport_cfg1 functions, the *lower
>>>>>> target* is programmed to busdev. Is it for any specific reason?
>>>>>> I mean doing that will leave lot of holes in the PCIe address space.
>>>>>> IIUC, if we don't set that to busdev, consecutive pcie address space will be
>>>>>> used for each function no?
>>>>>
>>>>> Yes, I think even if CX_ATU_MIN_REGION_SIZE is 64KB in any controller,
>>>>> bus, dev and function number can be used to define target address.
>>>>
>>>> I meant for function 0 the configuration space will be from (0x0 t0 0xfff -
>>>> 4KB). If we use *busdev* for programming target, for function 1 the
>>>> configuration space will start at 0x10000 PCIe address which will leave a small
>>>> hole from (0x1000 to 0xffff). I'm not sure if it will have a big impact though.
>>>> Also till we haven't exhausted the 64KB space (minimum), we wouldn't be needing
>>>> to program a new viewport. That's good enough to accommodate 18 functions for
>>>> the number of devices.
>>>
>>> Yes, I agree with you that using *busdev* will create hole and we
>>> should avoid it. More on this at the end.
>>>
>>>>>
>>>>> So you are trying to allocate statically a separate viewport for each
>>>>> function's cfg0 transfer (whereever sufficient number of viewport is
>>>>> avilable)?
>>>>
>>>> Actually in DRA7xx, we face a different problem in that, we can't program the
>>>> translation region directly from the ranges. Because while programming the
>>>> address translation window, the most significant 4 bits are not used.
>>>>
>>>> For example if you see, the cpu address of memory window starts @ 0x20012000
>>>> but while programming the address translation window we have to give 0x00012000.
>>>>
>>>> My dt data looked like this.
>>>> ranges = <0x00000800 0 0x20001000 0x20001000 0 0x00001000
>>>>         0x81000000 0 0          0x20002000 0 0x00010000
>>>>         0x82000000 0 0x20012000 0x20012000 0 0xffee000>;
>>>>
>>>> translation = <(OUTBOUND | INDEX0) CFG0 0x0 0x00001000 0x0000fff 0x0 0x00001000
>>>>              (OUTBOUND | INDEX1) IO   0x0 0x00002000 0x000ffff 0x0 0x00002000
>>>>              (OUTBOUND | INDEX2) MEM  0x0 0x00012000 0xffee000 0x0 0x20012000
>>>>> ;
>>>
>>> I too have some doubt here..not very clear.. may be someone more
>>> expert can correct (I keep arnd in cc).... How should be the
>>> translation?
>>> In my opinion, input address of translation should be in "bus address
>>> domain"  ie address what PCIe sees and translated output for memory
>>
>> It actually depends on whether we are configuring inbound or outbound. IIUC,
>> what you just mentioned will be for configuring inbound translation window.
>>
>> For the outbound translation window, it'll be the other way round. *base* will
>> be the CPU address and target will be the PCIe address.
>
> Sure? At the the end you say base address is 0x000_0000 (bus address) and not

This address is not actually a bus address (note it has only 28bits). 
Rather it's used only to program the address translation unit of 
desigware (for DRA7x).
Both the cpu address and pcie address is the same.
> 0x2000_0000 (parent bus address). It contradicts what you say above, no?
>>> transaction should be in "parent bus address domain" ie what CPUs
>>> see. If my understanding is correct, then pcie designware driver needs
>>> fixes at some places.
>>>
>>> I am not much used to DT, but if I understood correctly, in your case
>>> parent bus address and bus address are different.
>>>
>>> pp->mem_base = bus address  = range.pci_addr = 0x0000000000012000
>>> pp->config.mem_bus_addr = parent bus address = range.cpu_addr = 0x20012000
>>
>> Not like that. It's the same.
>> In DRA7, the cpu sees 32bit address, but the pcie controller can see only 28bit
>> address. So whenever the cpu issues a read/write request, the 4 most
>> significant bits are used by L3 to determine the target controller.
>> For example, the cpu reserves 0x2000_0000 - 0x2FFF_FFFF for PCIe controller but
>> the PCIe controller will see only (0x000_0000 - 0xFFF_FFF). So for programming
>> the outbound translation window the *base* should be programmed as 0x000_0000.
>> Whenever we try to write to say 0x2000_0000, it will be translated to whatever
>> we have programmed in the translation window with base as 0x000_0000.
>
> What you say here is also my understanding.
> Only question then remains, what should be translated address? All
> translated address must lie in the address range programmed in EP's
> BAR, then only EP will able to receive that mem transaction, no?

right.
> All EP's BAR address will lie in the range of pp->mem.start and
> pp->mem.end, am I correct here?

I'm not sure how the PCI core code sets the BAR of the EP. I have to 
check it.
> And, pp->mem.start is range.cpu_addr, therefore I said that if target address
> is programmed as cpu_address, it should work fine.

Agreed.

Thanks
Kishon

Re: [QUERY] Number of address translation regions in designware

[Marek Vasut]

Hi Kishon,

just curious, what's the current status of the DWC PCIe driver? How's the iATU 
issue going? Can you please update us a little?

Thank you!

Cheers!

Re: [QUERY] Number of address translation regions in designware

[Kishon Vijay Abraham I]

Hi,

On Friday 15 November 2013 06:10 AM, Marek Vasut wrote:
> Hi Kishon,
> 
> just curious, what's the current status of the DWC PCIe driver? How's the iATU 
> issue going? Can you please update us a little?

I was able to get it working in DRA7. Few of the dependent stuffs are not in
mainline yet (some clock related patches, rest framework changes, PHY changes).
Will post a RFC soon for pcie only part.

Thanks
Kishon

Re: [QUERY] Number of address translation regions in designware

[Jingoo Han]

On Friday, November 15, 2013 2:28 PM, Kishon Vijay Abraham I wrote:
> On Friday 15 November 2013 06:10 AM, Marek Vasut wrote:
> > Hi Kishon,
> >
> > just curious, what's the current status of the DWC PCIe driver? How's the iATU
> > issue going? Can you please update us a little?
> 
> I was able to get it working in DRA7. Few of the dependent stuffs are not in
> mainline yet (some clock related patches, rest framework changes, PHY changes).
> Will post a RFC soon for pcie only part.

OK, I see.
If you send the RFC patch, I will review ant test your patch
as soon as possible. Thank you for your effort. :-)

Best regards,
Jingoo Han

Re: [QUERY] Number of address translation regions in designware

[Marek Vasut]

Hi Kishon, Jingoo,

> On Friday, November 15, 2013 2:28 PM, Kishon Vijay Abraham I wrote:
> > On Friday 15 November 2013 06:10 AM, Marek Vasut wrote:
> > > Hi Kishon,
> > > 
> > > just curious, what's the current status of the DWC PCIe driver? How's
> > > the iATU issue going? Can you please update us a little?
> > 
> > I was able to get it working in DRA7. Few of the dependent stuffs are not
> > in mainline yet (some clock related patches, rest framework changes, PHY
> > changes). Will post a RFC soon for pcie only part.
> 
> OK, I see.
> If you send the RFC patch, I will review ant test your patch
> as soon as possible. Thank you for your effort. :-)

DTTO here, I can test it on MX6 as well. If you can roll out a prototype, I'm 
sure we can help in some ways too :)

Best regards,
Marek Vasut

Re: [QUERY] Number of address translation regions in designware

[Kishon Vijay Abraham I]

Hi,
On Friday 15 November 2013 09:07 PM, Marek Vasut wrote:
> Hi Kishon, Jingoo,
> 
>> On Friday, November 15, 2013 2:28 PM, Kishon Vijay Abraham I wrote:
>>> On Friday 15 November 2013 06:10 AM, Marek Vasut wrote:
>>>> Hi Kishon,
>>>>
>>>> just curious, what's the current status of the DWC PCIe driver? How's
>>>> the iATU issue going? Can you please update us a little?
>>>
>>> I was able to get it working in DRA7. Few of the dependent stuffs are not
>>> in mainline yet (some clock related patches, rest framework changes, PHY
>>> changes). Will post a RFC soon for pcie only part.
>>
>> OK, I see.
>> If you send the RFC patch, I will review ant test your patch
>> as soon as possible. Thank you for your effort. :-)
> 
> DTTO here, I can test it on MX6 as well. If you can roll out a prototype, I'm 
> sure we can help in some ways too :)

huh.. I didn't change much in designware code that would affect other
platforms. I just added a property base_mask that should be populated from the
dt data. (if it's not populated from the dt data, it will take the default
value of all f's). Here is the patch anyway.

Thanks
Kishon

commit b91b61d594f293d994d87f10eb8a1a3b2e5f8977
Author: Kishon Vijay Abraham I <kishon@ti.com>
Date:   Wed Oct 30 14:51:58 2013 +0530

    pci: host: pcie-designware: Use *base-mask* for configuring the iATU

    In DRA7, the cpu sees 32bit address, but the pcie controller can see only 28bit
    address. So whenever the cpu issues a read/write request, the 4 most
    significant bits are used by L3 to determine the target controller.
    For example, the cpu reserves 0x2000_0000 - 0x2FFF_FFFF for PCIe controller but
    the PCIe controller will see only (0x000_0000 - 0xFFF_FFF). So for programming
    the outbound translation window the *base* should be programmed as 0x000_0000.
    Whenever we try to write to say 0x2000_0000, it will be translated to whatever
    we have programmed in the translation window with base as 0x000_0000.

    Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>

diff --git a/Documentation/devicetree/bindings/pci/designware-pcie.txt
b/Documentation/devicetree/bindings/pci/designware-pcie.txt
index d5d26d4..fc04ab7 100644
--- a/Documentation/devicetree/bindings/pci/designware-pcie.txt
+++ b/Documentation/devicetree/bindings/pci/designware-pcie.txt
@@ -25,6 +25,7 @@ Optional properties for fsl,imx6q-pcie
 - power-on-gpio: gpio pin number of power-enable signal
 - wake-up-gpio: gpio pin number of incoming wakeup signal
 - disable-gpio: gpio pin number of outgoing rfkill/endpoint disable signal
+- base-mask: address mask for the PCIe controller target port

 Example:

diff --git a/drivers/pci/host/pcie-designware.c
b/drivers/pci/host/pcie-designware.c
index f879116..fef64cf 100644
--- a/drivers/pci/host/pcie-designware.c
+++ b/drivers/pci/host/pcie-designware.c
@@ -440,6 +440,9 @@ int __init dw_pcie_host_init(struct pcie_port *pp)
 		return -EINVAL;
 	}

+	if (of_property_read_u64(np, "base-mask", &pp->base_mask))
+		pp->base_mask = ~(0x0ULL);
+
 	if (IS_ENABLED(CONFIG_PCI_MSI)) {
 		pp->irq_domain = irq_domain_add_linear(pp->dev->of_node,
 					MAX_MSI_IRQS, &msi_domain_ops,
@@ -479,12 +482,15 @@ int __init dw_pcie_host_init(struct pcie_port *pp)

 static void dw_pcie_prog_viewport_cfg0(struct pcie_port *pp, u32 busdev)
 {
+	u64 cfg0_base;
+
+	cfg0_base = pp->cfg0_base & pp->base_mask;
 	/* Program viewport 0 : OUTBOUND : CFG0 */
 	dw_pcie_writel_rc(pp, PCIE_ATU_REGION_OUTBOUND | PCIE_ATU_REGION_INDEX0,
 			  PCIE_ATU_VIEWPORT);
-	dw_pcie_writel_rc(pp, pp->cfg0_base, PCIE_ATU_LOWER_BASE);
-	dw_pcie_writel_rc(pp, (pp->cfg0_base >> 32), PCIE_ATU_UPPER_BASE);
-	dw_pcie_writel_rc(pp, pp->cfg0_base + pp->config.cfg0_size - 1,
+	dw_pcie_writel_rc(pp, cfg0_base, PCIE_ATU_LOWER_BASE);
+	dw_pcie_writel_rc(pp, (cfg0_base >> 32), PCIE_ATU_UPPER_BASE);
+	dw_pcie_writel_rc(pp, cfg0_base + pp->config.cfg0_size - 1,
 			  PCIE_ATU_LIMIT);
 	dw_pcie_writel_rc(pp, busdev, PCIE_ATU_LOWER_TARGET);
 	dw_pcie_writel_rc(pp, 0, PCIE_ATU_UPPER_TARGET);
@@ -494,14 +500,17 @@ static void dw_pcie_prog_viewport_cfg0(struct pcie_port
*pp, u32 busdev)

 static void dw_pcie_prog_viewport_cfg1(struct pcie_port *pp, u32 busdev)
 {
+	u64 cfg1_base;
+
+	cfg1_base = pp->cfg1_base & pp->base_mask;
 	/* Program viewport 1 : OUTBOUND : CFG1 */
 	dw_pcie_writel_rc(pp, PCIE_ATU_REGION_OUTBOUND | PCIE_ATU_REGION_INDEX1,
 			  PCIE_ATU_VIEWPORT);
 	dw_pcie_writel_rc(pp, PCIE_ATU_TYPE_CFG1, PCIE_ATU_CR1);
 	dw_pcie_writel_rc(pp, PCIE_ATU_ENABLE, PCIE_ATU_CR2);
-	dw_pcie_writel_rc(pp, pp->cfg1_base, PCIE_ATU_LOWER_BASE);
-	dw_pcie_writel_rc(pp, (pp->cfg1_base >> 32), PCIE_ATU_UPPER_BASE);
-	dw_pcie_writel_rc(pp, pp->cfg1_base + pp->config.cfg1_size - 1,
+	dw_pcie_writel_rc(pp, cfg1_base, PCIE_ATU_LOWER_BASE);
+	dw_pcie_writel_rc(pp, (cfg1_base >> 32), PCIE_ATU_UPPER_BASE);
+	dw_pcie_writel_rc(pp, cfg1_base + pp->config.cfg1_size - 1,
 			  PCIE_ATU_LIMIT);
 	dw_pcie_writel_rc(pp, busdev, PCIE_ATU_LOWER_TARGET);
 	dw_pcie_writel_rc(pp, 0, PCIE_ATU_UPPER_TARGET);
@@ -509,14 +518,17 @@ static void dw_pcie_prog_viewport_cfg1(struct pcie_port
*pp, u32 busdev)

 static void dw_pcie_prog_viewport_mem_outbound(struct pcie_port *pp)
 {
+	u64 mem_base;
+
+	mem_base = pp->mem_base & pp->base_mask;
 	/* Program viewport 0 : OUTBOUND : MEM */
 	dw_pcie_writel_rc(pp, PCIE_ATU_REGION_OUTBOUND | PCIE_ATU_REGION_INDEX0,
 			  PCIE_ATU_VIEWPORT);
 	dw_pcie_writel_rc(pp, PCIE_ATU_TYPE_MEM, PCIE_ATU_CR1);
 	dw_pcie_writel_rc(pp, PCIE_ATU_ENABLE, PCIE_ATU_CR2);
-	dw_pcie_writel_rc(pp, pp->mem_base, PCIE_ATU_LOWER_BASE);
-	dw_pcie_writel_rc(pp, (pp->mem_base >> 32), PCIE_ATU_UPPER_BASE);
-	dw_pcie_writel_rc(pp, pp->mem_base + pp->config.mem_size - 1,
+	dw_pcie_writel_rc(pp, mem_base, PCIE_ATU_LOWER_BASE);
+	dw_pcie_writel_rc(pp, (mem_base >> 32), PCIE_ATU_UPPER_BASE);
+	dw_pcie_writel_rc(pp, mem_base + pp->config.mem_size - 1,
 			  PCIE_ATU_LIMIT);
 	dw_pcie_writel_rc(pp, pp->config.mem_bus_addr, PCIE_ATU_LOWER_TARGET);
 	dw_pcie_writel_rc(pp, upper_32_bits(pp->config.mem_bus_addr),
@@ -525,14 +537,17 @@ static void dw_pcie_prog_viewport_mem_outbound(struct
pcie_port *pp)

 static void dw_pcie_prog_viewport_io_outbound(struct pcie_port *pp)
 {
+	u64 io_base;
+
+	io_base = pp->io_base & pp->base_mask;
 	/* Program viewport 1 : OUTBOUND : IO */
 	dw_pcie_writel_rc(pp, PCIE_ATU_REGION_OUTBOUND | PCIE_ATU_REGION_INDEX1,
 			  PCIE_ATU_VIEWPORT);
 	dw_pcie_writel_rc(pp, PCIE_ATU_TYPE_IO, PCIE_ATU_CR1);
 	dw_pcie_writel_rc(pp, PCIE_ATU_ENABLE, PCIE_ATU_CR2);
-	dw_pcie_writel_rc(pp, pp->io_base, PCIE_ATU_LOWER_BASE);
-	dw_pcie_writel_rc(pp, (pp->io_base >> 32), PCIE_ATU_UPPER_BASE);
-	dw_pcie_writel_rc(pp, pp->io_base + pp->config.io_size - 1,
+	dw_pcie_writel_rc(pp, io_base, PCIE_ATU_LOWER_BASE);
+	dw_pcie_writel_rc(pp, (io_base >> 32), PCIE_ATU_UPPER_BASE);
+	dw_pcie_writel_rc(pp, io_base + pp->config.io_size - 1,
 			  PCIE_ATU_LIMIT);
 	dw_pcie_writel_rc(pp, pp->config.io_bus_addr, PCIE_ATU_LOWER_TARGET);
 	dw_pcie_writel_rc(pp, upper_32_bits(pp->config.io_bus_addr),
diff --git a/drivers/pci/host/pcie-designware.h
b/drivers/pci/host/pcie-designware.h
index c15379b..2fe1dc5 100644
--- a/drivers/pci/host/pcie-designware.h
+++ b/drivers/pci/host/pcie-designware.h
@@ -35,6 +35,7 @@ struct pcie_port {
 	struct device		*dev;
 	u8			root_bus_nr;
 	void __iomem		*dbi_base;
+	u64			base_mask;
 	u64			cfg0_base;
 	void __iomem		*va_cfg0_base;
 	u64			cfg1_base;
> 
> Best regards,
> Marek Vasut
> 

Re: [QUERY] Number of address translation regions in designware

[Arnd Bergmann]

On Monday 18 November 2013, Kishon Vijay Abraham I wrote:
> commit b91b61d594f293d994d87f10eb8a1a3b2e5f8977
> Author: Kishon Vijay Abraham I <kishon@ti.com>
> Date:   Wed Oct 30 14:51:58 2013 +0530
> 
>     pci: host: pcie-designware: Use *base-mask* for configuring the iATU
> 
>     In DRA7, the cpu sees 32bit address, but the pcie controller can see only 28bit
>     address. So whenever the cpu issues a read/write request, the 4 most
>     significant bits are used by L3 to determine the target controller.
>     For example, the cpu reserves 0x2000_0000 - 0x2FFF_FFFF for PCIe controller but
>     the PCIe controller will see only (0x000_0000 - 0xFFF_FFF). So for programming
>     the outbound translation window the base should be programmed as 0x000_0000.
>     Whenever we try to write to say 0x2000_0000, it will be translated to whatever
>     we have programmed in the translation window with base as 0x000_0000.
> 
>     Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>

Sorry I didn't see that patch earlier. Have you had a look at the definition of the
"dma-ranges" property? I think that is something we have already defined that can
handle this in a more generic way.

	Arnd