Received-SPF: pass (google.com: domain of linux-wireless-owner@vger.kernel.org designates 2620:137:e000::3:8 as permitted sender) client-ip=2620:137:e000::3:8;
From:   Kang Yang <quic_kangyang@quicinc.com>
To:     <ath12k@lists.infradead.org>
CC:     <linux-wireless@vger.kernel.org>, <quic_kangyang@quicinc.com>
Subject: [PATCH 6/7] wifi: ath12k: do not restore ASPM in case of single MSI vector
Date:   Mon, 20 Nov 2023 18:15:42 +0800
Message-ID: <20231120101543.4369-7-quic_kangyang@quicinc.com>
In-Reply-To: <20231120101543.4369-1-quic_kangyang@quicinc.com>
References: <20231120101543.4369-1-quic_kangyang@quicinc.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Content-Type: text/plain
Precedence: bulk

Current code enables ASPM by default, it allows MHI to enter M2 state.
In case of one MSI vector, system hang is observed if ath12k does MHI
register reading in this state.

The workaround here is to prevent MHI from entering M2 state, this can
be done by disabling ASPM if only one MSI vector is used. When using 32
vectors ASPM is enabled as before.

Tested-on: WCN7850 hw2.0 PCI WLAN.HMT.1.0-03427-QCAHMTSWPL_V1.0_V2.0_SILICONZ-1.15378.4

Signed-off-by: Kang Yang <quic_kangyang@quicinc.com>
---
 drivers/net/wireless/ath/ath12k/pci.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/net/wireless/ath/ath12k/pci.c b/drivers/net/wireless/ath/ath12k/pci.c
index 4484bac18f4e..3850331438de 100644
--- a/drivers/net/wireless/ath/ath12k/pci.c
+++ b/drivers/net/wireless/ath/ath12k/pci.c
@@ -1094,7 +1094,10 @@ int ath12k_pci_start(struct ath12k_base *ab)
 
 	set_bit(ATH12K_PCI_FLAG_INIT_DONE, &ab_pci->flags);
 
-	ath12k_pci_aspm_restore(ab_pci);
+	if (test_bit(ATH12K_PCI_FLAG_MULTI_MSI_VECTORS, &ab_pci->flags))
+		ath12k_pci_aspm_restore(ab_pci);
+	else
+		ath12k_info(ab, "leaving PCI ASPM disabled to avoid MHI M2 problems\n");
 
 	ath12k_pci_ce_irqs_enable(ab);
 	ath12k_ce_rx_post_buf(ab);
-- 
2.34.1