Hi Krzysztof

On 30/01/2025 13:25, Krzysztof Kozlowski wrote:

On 30/01/2025 14:08, Florent Tomasin wrote:

quoted

Allow mali-valhall-csf driver to retrieve a protected
heap at probe time by passing the name of the heap
as attribute to the device tree GPU node.

Please wrap commit message according to Linux coding style / submission
process (neither too early nor over the limit):
https://elixir.bootlin.com/linux/v6.4-rc1/source/Documentation/process/submitting-patches.rst#L597

Apologies, I think I made quite few other mistakes in the style of the
patches I sent. I will work on improving this aspect, appreciated

Why this cannot be passed by phandle, just like all reserved regions?

From where do you take these protected heaps? Firmware? This would
explain why no relation is here (no probe ordering, no device links,
nothing connecting separate devices).

The protected heap is generaly obtained from a firmware (TEE) and could
sometimes be a carved-out memory with restricted access.

The Panthor CSF kernel driver does not own or manage the protected heap
and is instead a consumer of it (assuming the heap is made available by
the system integrator).

I initially used a phandle, but then I realised it would introduce a new
API to share the heap across kernel driver. In addition I found this
patch series:
-
https://lore.kernel.org/lkml/20230911023038.30649-1-yong.wu@mediatek.com/#t (local)

which introduces a DMA Heap API to the rest of the kernel to find a
heap by name:
- dma_heap_find()

I then decided to follow that approach to help isolate the heap
management from the GPU driver code. In the Panthor driver, if the
heap is not found at probe time, the driver will defer the probe until
the exporter made it available.

Best regards,
Florent