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authorJeremy Compostella <jeremy.compostella@intel.com>2023-03-13 13:59:08 -0700
committerSubrata Banik <subratabanik@google.com>2023-04-07 04:50:47 +0000
commit1d79188dc502da444db5874d303ef581a6ea6017 (patch)
treeeba0ff4acbafc585bf9ccde84afcc956f60038f3 /src/mainboard/google/auron
parent74b4bd0e92a77635bbb584d8b7913deb9a134da7 (diff)
soc/intel/cmn/cse: Handle EOP completion asynchronously
coreboot supports three instances of sending EOP: 1. At CSE `.final' device operation 2. Early as with Alder Lake in chip_operations.init if `SOC_INTEL_CSE_SEND_EOP_EARLY' is selected 3. At BS_PAYLOAD_BOOT as designed for Meteor Lake if `SOC_INTEL_CSE_SEND_EOP_LATE' is selected Currently, Alder Lake uses #3 as it results in better and more stable boot time. However, what would deliver even better result is to not actively wait for CSE completion. This patch introduces a new `SOC_INTEL_CSE_SEND_EOP_ASYNC' Kconfig which split the action of sending EOP request and receiving EOP completion response from the CSE. This patch used in conjunction with #1 can significantly improves the overall boot time on a Raptor Lake design. For example `SOC_INTEL_CSE_SEND_EOP_ASYNC' on a skolas board can deliver up to 36 ms boot time improvement as illustrated below. | # | Late EOP | Async EOP | |----------+----------+-----------| | 1 | 1020.052 | 971.272 | | 2 | 1015.911 | 971.821 | | 3 | 1038.415 | 1021.841 | | 4 | 1020.657 | 993.751 | | 5 | 1065.128 | 1020.951 | | 6 | 1037.859 | 1023.326 | | 7 | 1042.010 | 984.412 | |----------+----------+-----------| | Mean | 1034.29 | 998.20 | | Variance | 4.76 % | 5.21 % | The improvement is not stable but comparing coreboot and FSP performance timestamps demonstrate that the slowness is caused by a lower memory frequency (SaGv point) at early boot which is not an issue addressed by this patch. We also observe some improvement on an Alder Lake design. For example, the same configuration on a kano board can deliver up to 10 ms boot time improvement as illustrated below. | # | Late EOP | Async EOP | |----------+----------+-----------| | 0 | 1067.719 | 1050.106 | | 1 | 1058.263 | 1056.836 | | 2 | 1064.091 | 1056.709 | | 3 | 1068.614 | 1055.042 | | 4 | 1065.749 | 1056.732 | | 5 | 1069.838 | 1057.846 | | 6 | 1066.897 | 1053.548 | | 7 | 1060.850 | 1051.911 | |----------+----------+-----------| | Mean | 1065.25 | 1054.84 | The improvement is more limited on kano because a longer PCIe initialization delays EOP in the Late EOP configuration which make it faster to complete. CSME team confirms that: 1. End-Of-Post is a blocking command in the sense that BIOS is requested to wait for the command completion before loading the OS or second stage bootloader. 2. The BIOS is not required to actively wait for completion of the command and can perform other operations in the meantime as long as they do not involve HECI commands. On Raptor Lake, coreboot does not send any HECI command after End-Of-Post. FSP-s code review did not reveal any HECI command being sent as part of the `AFTER_PCI_ENUM', `READY_TO_BOOT' or `END_OF_FIRMWARE' notifications. If any HECI send and receive command has been sent the extra code added in `cse_receive_eop()' should catch it. According to commit 387ec919d9f7 ("soc/intel/alderlake: Select SOC_INTEL_CSE_SEND_EOP_LATE"), FSP-silicon can sometimes (on the first boot after flashing of a Marasov board for instance) request coreboot to perform a global request out of AFTER_PCI_ENUM notification. Global request relies on a HECI command. Even though, we tested that it does not create any issue, `SOC_INTEL_CSE_SEND_EOP_ASYNC' flag should not be associated to the `SOC_INTEL_CSE_SEND_EOP_EARLY' flag to prevent potential a global reset command to "conflict" with the EOP command. This patch also introduces a new code logic to detect if CSE is in the right state to handle the EOP command. Otherwise, it uses the prescribed method to make the CSE function disable. The typical scenario is the ChromeOS recovery boot where CSE stays in RO partition and therefore EOP command should be avoided. [DEBUG] BS: BS_PAYLOAD_LOAD exit times (exec / console): 0 / 14 ms [INFO ] HECI: coreboot in recovery mode; found CSE in expected SOFT TEMP DISABLE state, skipping EOP [INFO ] Disabling Heci using PMC IPC [WARN ] HECI: CSE device 16.0 is hidden [WARN ] HECI: CSE device 16.1 is disabled [WARN ] HECI: CSE device 16.2 is disabled [WARN ] HECI: CSE device 16.3 is disabled [WARN ] HECI: CSE device 16.4 is disabled [WARN ] HECI: CSE device 16.5 is disabled BUG=b:276339544 BRANCH=firmware-brya-14505.B TEST=Tests on brya0 with and `SOC_INTEL_CSE_SEND_EOP_ASYNC' show End-Of-Post sent soon after FSP-s and EOP message receive at `BS_PAYLOAD_BOOT'. Verify robustness by injecting a `GET_BOOT_STATE' HECI command with or without `heci_reset'. The implementation always successfully completed the EOP before moving to the payload. As expected, the boot time benefit of the asynchronous solution was under some injection scenario undermined by this unexpected HECI command. Signed-off-by: Jeremy Compostella <jeremy.compostella@intel.com> Signed-off-by: Subrata Banik <subratabanik@google.com> Change-Id: I01a56bfe3f6c37ffb5e51a527d9fe74785441c5a Reviewed-on: https://review.coreboot.org/c/coreboot/+/74214 Tested-by: build bot (Jenkins) <no-reply@coreboot.org> Reviewed-by: Nick Vaccaro <nvaccaro@google.com> Reviewed-by: Tarun Tuli <taruntuli@google.com>
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