Re: [PATCH v2 3/6] dt-bindings: PCI: ti,am65: Extend for use with PVU

Jan Kiszka
2024-08-27T09:22:13Z

On 27.08.24 08:37, Krzysztof Kozlowski wrote:
> On Mon, Aug 26, 2024 at 11:50:04PM +0200, Jan Kiszka wrote:
>> From: Jan Kiszka <jan.kiszka@siemens.com>
>>
>> Describe also the VMAP registers which are needed in order to make use
>> of the PVU with this PCI host. Furthermore, permit to specify a
>> restricted DMA pool by phandle.
>
> That's an ABI break without explanation why it is necessary.
>

It is needed in order to support the PVU, as written above.

Previous versions of this binding likely didn't consider this use case
and therefore didn't describe all registers associated with the hardware.

BTW, if you see a way to add the required registers without breaking
more than needed, I'm all ears. At least the kernel driver will continue
to work with older DTs when you disable PVU support or do not add a DMA
pool to the DT.

Jan

>>
>> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
>> ---
>> .../devicetree/bindings/pci/ti,am65-pci-host.yaml | 13 ++++++++++---
>> 1 file changed, 10 insertions(+), 3 deletions(-)
>>
>> diff --git a/Documentation/devicetree/bindings/pci/ti,am65-pci-host.yaml b/Documentation/devicetree/bindings/pci/ti,am65-pci-host.yaml
>> index 0a9d10532cc8..72f78f21e1e8 100644
>> --- a/Documentation/devicetree/bindings/pci/ti,am65-pci-host.yaml
>> +++ b/Documentation/devicetree/bindings/pci/ti,am65-pci-host.yaml
>> @@ -20,7 +20,7 @@ properties:
>> - ti,keystone-pcie
>>
>> reg:
>> - maxItems: 4
>> + maxItems: 6
>>
>> reg-names:
>> items:
>> @@ -28,6 +28,8 @@ properties:
>> - const: dbics
>> - const: config
>> - const: atu
>> + - const: vmap_lp
>> + - const: vmap_hp
>>
>> interrupts:
>> maxItems: 1
>> @@ -69,6 +71,9 @@ properties:
>> items:
>> pattern: '^pcie-phy[0-1]$'
>>
>> + memory-region:
>> + description: phandle to restricted DMA pool to be used for all devices behind this controller
>
> missing constraints, maxItems
>
> Best regards,
> Krzysztof
>

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