[M] Change in coreboot[main]: device/pciexp_device.c: Fix setting Max Payload Size

[Michał Żygowski (Code Review)]

Attention is currently required from: Angel Pons, Arthur Heymans, Felix Held, Krystian Hebel, Kyösti Mälkki, Michał Żygowski, Nico Huber, Patrick Rudolph.

Michał Żygowski has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/77338?usp=email )

Change subject: device/pciexp_device.c: Fix setting Max Payload Size
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Patch Set 12:

(5 comments)

File src/device/pciexp_device.c:

https://review.coreboot.org/c/coreboot/+/77338/comment/74fc411f_6bd48d71 :
PS10, Line 709: pciexp_configure_max_payload
> Finally figured out how it should work. […]

This is done. Also, when the scan bus on root port is finished, the root port's current max payload size in synced to all downstream devices of this port.

File src/device/pciexp_device.c:

https://review.coreboot.org/c/coreboot/+/77338/comment/230f1e58_6c12c4cf :
PS11, Line 594: root_devcap
> The name no longer describes what this variable holds.

Changed the variable names to child and parent where appropriate.

https://review.coreboot.org/c/coreboot/+/77338/comment/7d084851_a74a2dc3 :
PS11, Line 598: awlays
> always

Fixed

https://review.coreboot.org/c/coreboot/+/77338/comment/a98d6e6b_54f5db11 :
PS11, Line 608:  & PCI_EXP_DEVCAP_PAYLOAD
> No need to mask it here, it was already masked right after reading.

Fixed

https://review.coreboot.org/c/coreboot/+/77338/comment/144cfb83_69355013 :
PS11, Line 630: 	root->max_payload_set = 1;
> Exactly. […]

Ad.2. Second walk implemented in patchset 12