[RFC] feat(linux): s2idle: Document the mode selection logic#641
[RFC] feat(linux): s2idle: Document the mode selection logic#641DhruvaG2000 wants to merge 1 commit intoTexasInstruments:masterfrom
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Document the mode selection logic using the s2idle flow Signed-off-by: Dhruva Gole <d-gole@ti.com>
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devarsht,
DhruvaG2000,
gehariprasath,
praneethbajjuri,
r-vignesh,
uditkumarti and
vishalmti
kwillis01
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kwillis01
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It might be good to see if there are other places in the previous parts of the doc that can be updated or that the new info can loop into and consolidate.
| Power Domain Hierarchy in Device Tree | ||
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| The power domain hierarchy in the Device Tree defines how different system components are grouped |
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nit: s/Device Tree/device tree
| The Device Tree defines multiple idle states at each level of the hierarchy, each with different | ||
| power/latency trade-offs: | ||
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| **CPU-Level Idle States:** |
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Not sure if the code blocks really say that much. Might be better to explain what each state does and then link to the code for people to look into if they want to.
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| Understanding the Suspend Parameters |
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IMO everything in this section should somehow be combined with the "Understanding the Suspend Parameter" from above so it all flows together well. Having these in separate sections makes the info feel disjointed and that you might be repeating a lot of the same info. It can be placed here or earlier on, but preferably together.
| 3. Only idle states with ``exit-latency-us`` ≤ constraint are considered | ||
| 4. The deepest eligible state is selected | ||
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| **Example: Deep Sleep Mode Selection:** |
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I think this should be moved after the explanation of "Selecting Specific Low-Power Modes" and "How It Sets QoS Constraints" so the example comes after the explanation.
| - **State Type = 1 (Power Down)**: Context is lost; firmware must restore state on resume | ||
| - **State ID = 0x2235**: Platform-specific identifier that the PSCI firmware (TF-A) recognizes | ||
| as "Deep Sleep" mode where DDR is in Self-Refresh and more peripherals in the Main domain | ||
| remain powered compared to RTC+DDR mode, providing faster resume at the cost of higher power |
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Comparison to RTC + DDR not needed because of the differences section below. Removing it makes this section a little simpler.
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Document the mode selection logic using the s2idle flow