From 00864fdba65b4b466bbc7ba599b84b6ac8e8b1c6 Mon Sep 17 00:00:00 2001 From: Tim Van Patten Date: Fri, 15 Sep 2023 10:48:35 -0600 Subject: [PATCH] mb/google/guybrush: Disable WLAN ASPM ASPM on the WLAN PCIe bus introduces large latency spikes, which can be measured with cyclictest: $ cyclictest --policy=rr --priority=12 --interval=10000 --threads=1 --loops=6000 Disabling ASPM for WLAN reduces the latency spikes from 2,500-3,000 usec down to 35-65 usec. These latency spikes can impact the user when real-time processes like Audio (cras) are starved of CPU time, leading to buffer underruns resulting in crackling/distorted audio. ASPM is already disabled for Nipperkin devices (CB:63537), so this CL disables it for both in the shared declaration of guybrush_czn_dxio_descriptors. Power impact for Dewatt: * ASPM enabled power_VideoCall.FDO_25min_webrtc w_energy_rate 7.425043688811071 power_Idle.default20min wh_energy_used 1.4164200000000022 * ASPM disabled power_VideoCall.FDO_25min_webrtc w_energy_rate 8.779998551703423 power_Idle.default20min wh_energy_used 1.4860800000000012 When using Google Meet over WiFi, power increases by ~1.5W. BUG=b:297970318 TEST=cyclictest --policy=rr --priority=12 --interval=10000 --threads=1 --loops=6000 Change-Id: I16940987d598943bd5d6ace8b4008eba4d4a177c Signed-off-by: Tim Van Patten Reviewed-on: https://review.coreboot.org/c/coreboot/+/77963 Reviewed-by: Martin L Roth Tested-by: build bot (Jenkins) Reviewed-by: Karthik Ramasubramanian --- src/mainboard/google/guybrush/port_descriptors.c | 4 ++-- src/mainboard/google/guybrush/variants/nipperkin/variant.c | 4 ---- 2 files changed, 2 insertions(+), 6 deletions(-) diff --git a/src/mainboard/google/guybrush/port_descriptors.c b/src/mainboard/google/guybrush/port_descriptors.c index 49fe617c7f..fc6ccb8968 100644 --- a/src/mainboard/google/guybrush/port_descriptors.c +++ b/src/mainboard/google/guybrush/port_descriptors.c @@ -18,8 +18,8 @@ static fsp_dxio_descriptor guybrush_czn_dxio_descriptors[] = { .device_number = PCI_SLOT(WLAN_DEVFN), .function_number = PCI_FUNC(WLAN_DEVFN), .link_aspm = ASPM_L1, - .link_aspm_L1_1 = true, - .link_aspm_L1_2 = true, + .link_aspm_L1_1 = false, + .link_aspm_L1_2 = false, .turn_off_unused_lanes = true, .clk_req = CLK_REQ0, .port_params = {PP_PSPP_AC, 0x133, PP_PSPP_DC, 0x122} diff --git a/src/mainboard/google/guybrush/variants/nipperkin/variant.c b/src/mainboard/google/guybrush/variants/nipperkin/variant.c index 48e768d182..bd6c48ca86 100644 --- a/src/mainboard/google/guybrush/variants/nipperkin/variant.c +++ b/src/mainboard/google/guybrush/variants/nipperkin/variant.c @@ -1,13 +1,9 @@ /* SPDX-License-Identifier: GPL-2.0-or-later */ #include -#include void variant_update_dxio_descriptors(fsp_dxio_descriptor *dxio_descriptors) { - dxio_descriptors[WLAN].link_aspm_L1_1 = false; - dxio_descriptors[WLAN].link_aspm_L1_2 = false; - /* Fix link speed to GEN2 - b/228830362 */ dxio_descriptors[WLAN].link_speed_capability = GEN2; dxio_descriptors[WLAN].port_params[0] = PP_PSPP_AC;