Hi,
On Mon, 27 Feb 2023 at 06:20, Tao Zhang quic_taozha@quicinc.com wrote:
Hi Mike,
在 2/24/2023 11:43 PM, Tao Zhang 写道:
Hi Mike,
I have a question about the following code you promoted.
Patch - coresight: cti: Add device tree support for v8 arch CTI
You set the following mask variables in the function "cti_plat_create_v8_connections".
tc->con_in->used_mask = 0x3; /* sigs <0 1> */
tc->con_out->used_mask = 0x7; /* sigs <0 1 2 > */
Could you tell us why they should be set to 0x3 and 0x7 here?
Is there any particular reason for this design?
Add more background on this question below.
The CPU CTIs we use based on the CTI v8 architecture that support more trigger number for the trigger in and trigger out.
If we configured "arm,coresight-cti-v8-arch" for CPU CTIs in the device tree, it will causes the trigger number to be unavailable.
CTI's in v8 attached to the CPU have an architecturally mandated set of triggers - this is the set that is defined with this compatible. This is designed to save effort in describing the elements in the device tree.
Is there any way to solve the problem we have now?
Is it possible to change the trigger number supported by CPU CTIs by configuring device tree?
For custom CTIs use the arm,coresight-cti compatible, and describe your CTI as shown in ./Documentation/devicetree/bindings/arm/arm.coresight-cti.yaml This has an example of custom CTI bindings
Regards
Mike
Best,
Tao
Best,
Tao