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From:   Kang Yang <quic_kangyang@quicinc.com>
To:     <ath12k@lists.infradead.org>
CC:     <linux-wireless@vger.kernel.org>, <quic_kangyang@quicinc.com>
Subject: [PATCH 1/7] wifi: ath12k: get msi_data again after request_irq is called
Date:   Mon, 20 Nov 2023 18:15:37 +0800
Message-ID: <20231120101543.4369-2-quic_kangyang@quicinc.com>
In-Reply-To: <20231120101543.4369-1-quic_kangyang@quicinc.com>
References: <20231120101543.4369-1-quic_kangyang@quicinc.com>
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The reservation mode of interrupts in kernel assigns a dummy vector
when the interrupt is allocated and assigns a real vector when the
request_irq is called. The reservation mode helps to ease vector
pressure when devices with a large amount of queues/interrupts are
initialized, but only a minimal subset of those queues/interrupts
is actually used.

So on reservation mode, the msi_data may change after request_irq is
called, then it will lead to spurious interrupt. But when VT-d in
BIOS is enabled and ath12k can get 32 MSI vectors, ath12k always get
the same msi_data before and after request_irq.

So in case of one MSI vector, ath12k need read msi_data again after
request_irq is called, and then the correct msi_data is programmed
into WCN7850 hardware components.

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 | 30 +++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)

diff --git a/drivers/net/wireless/ath/ath12k/pci.c b/drivers/net/wireless/ath/ath12k/pci.c
index 3006cd3fbe11..c5bc9afaa9fc 100644
--- a/drivers/net/wireless/ath/ath12k/pci.c
+++ b/drivers/net/wireless/ath/ath12k/pci.c
@@ -708,6 +708,25 @@ static void ath12k_pci_msi_free(struct ath12k_pci *ab_pci)
 	pci_free_irq_vectors(ab_pci->pdev);
 }
 
+static int ath12k_pci_config_msi_data(struct ath12k_pci *ab_pci)
+{
+	struct msi_desc *msi_desc;
+
+	msi_desc = irq_get_msi_desc(ab_pci->pdev->irq);
+	if (!msi_desc) {
+		ath12k_err(ab_pci->ab, "msi_desc is NULL!\n");
+		pci_free_irq_vectors(ab_pci->pdev);
+		return -EINVAL;
+	}
+
+	ab_pci->msi_ep_base_data = msi_desc->msg.data;
+
+	ath12k_dbg(ab_pci->ab, ATH12K_DBG_PCI, "pci after request_irq msi_ep_base_data %d\n",
+		   ab_pci->msi_ep_base_data);
+
+	return 0;
+}
+
 static int ath12k_pci_claim(struct ath12k_pci *ab_pci, struct pci_dev *pdev)
 {
 	struct ath12k_base *ab = ab_pci->ab;
@@ -1286,6 +1305,17 @@ static int ath12k_pci_probe(struct pci_dev *pdev,
 		goto err_ce_free;
 	}
 
+	/* kernel may allocate a dummy vector before request_irq and
+	 * then allocate a real vector when request_irq is called.
+	 * So get msi_data here again to avoid spurious interrupt
+	 * as msi_data will configured to srngs.
+	 */
+	ret = ath12k_pci_config_msi_data(ab_pci);
+	if (ret) {
+		ath12k_err(ab, "failed to config msi_data: %d\n", ret);
+		goto err_free_irq;
+	}
+
 	ret = ath12k_core_init(ab);
 	if (ret) {
 		ath12k_err(ab, "failed to init core: %d\n", ret);
-- 
2.34.1