Re: [PATCH v5 1/4] dt-bindings: media: qcom,venus-common: Add IOMMU IOVA reservation region

On 7/29/2026 5:51 PM, Konrad Dybcio wrote:
> On 7/23/26 12:44 PM, Vikash Garodia wrote:
>>
>> On 7/23/2026 2:36 PM, Konrad Dybcio wrote:
>>> On 7/23/26 12:03 AM, Bryan O'Donoghue wrote:
>>>> On 22/07/2026 14:41, Vikash Garodia wrote:
>>>>> Update the memory-region property to support two regions:
>>>>> 1. Firmware-loaded codec carveout (existing)
>>>>> 2. IOMMU IOVA reservation region (new)
>>>>>
>>>>> The IOMMU IOVA reservation region is required to restrict usage of
>>>>> specific IOVA memory range. For example, VPU restricts usage of 600MB
>>>>> for specific streams, which could otherwise lead to device crash. This
>>>>> change allows platforms to define separate memory regions for codec
>>>>> carveout and IOVA restrictions.
>>>>> This schema update supports existing DTS having single memory-region,
>>>>> thereby allowing gradual migration of DTS to support two memory region.
>>>>>
>>>>> Signed-off-by: Vikash Garodia<[email protected]>
>>>>> ---
>>>>
>>>> I'm not mega-happy with this pattern being used - I prefer the pixel pixel_cb sub-node model you've proposed yourself.
>>>>
>>>> OTOH you're the maintainer so its really up to you how you want to arbitrate this - the 600MB constraint will work even if its not pretty or the best thing (tm).
>>>>
>>>> Reviewed-by: Bryan O'Donoghue <[email protected]>
>>>
>>> Doesn't this cause the same limitation that the initial patch
>>> by Daniel (all HW contexts can't access 0-600MiB anymore)?
>>
>> Yes, it does, but for cases, like Shikra, which have single streams (with SMRs), there is no additional benefit in going with sub nodes in such case.
> 
> Please note that somewhere, I was under the impression all venus
> impls suffer from that

Yes, all of venus/iris, including Shikra, have this limitation. I was 
trying to convey that for single stream case, like that of Shikra, we 
can specify the restrictive IOVA range in the parent iris node itself 
instead of introducing a sub node and put the same restriction there.

Regards,
Vikash

> 
> Konrad