intpm: use MMIO for AMD EFCH CPUs #1437
Open
+32
−11
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Recent AMD CPUs (SMBus PCI revision ID >= 0x51) can disable port-mapped IO and only support memory-mapped IO. In practice this was observed on a Zen 3 CPU where PMIO reads all returned 0xff. Update the driver to use MMIO for these processors while continuing to use PMIO by default.
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
I observed an issue when attempting to use SMBus devices on an AMD Zen3 7443P CPU where running
smbmsg -pfound no devices. Previously I used a Zen2 7702P CPU in the same chassis/motherboard and had no issue finding or accessing SMBus devices. Debugging the intsmb driver (source file intpm.c) showed all the PMIO reads were returning 0xff on Zen3.A comment in the Linux i2c-piix4.c source pointed me to the root cause:
Indeed, the revision ID of both the Zen2 and Zen3 CPUs is 0x61. I added a test for this condition and when true, set and allocate resources using MMIO instead of PMIO. I now see valid results from
smbmsg -pand am able to use SMBus devices on both the Zen2 and Zen3 CPUs using MMIO.