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From:   Carl Huang <cjhuang@codeaurora.org>
To:     ath11k@lists.infradead.org
Cc:     linux-wireless@vger.kernel.org
Subject: [PATCH 1/6] ath11k: get msi_data again after request_irq is called
Date:   Tue, 22 Dec 2020 22:02:20 -0500
Message-Id: <20201223030225.2345-2-cjhuang@codeaurora.org>
In-Reply-To: <20201223030225.2345-1-cjhuang@codeaurora.org>
References: <20201223030225.2345-1-cjhuang@codeaurora.org>
Precedence: bulk

The reservation mode of interrupts is 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, so ath11k reads msi_data again after request_irq is called,
and then the correct msi_data is programmed into QCA6390 hardware
components. Without this change, spurious interrupt occurs in case of
one MSI vector. When VT-D in BIOS is enabled and ath11k can get 32 MSI
vectors, ath11k always get the same msi_data before and after request_irq,
that's why this change is only required when one MSI vector is to be
supported.

Tested-on: QCA6390 hw2.0 PCI WLAN.HST.1.0.1-01740-QCAHSTSWPLZ_V2_TO_X86-1

Signed-off-by: Carl Huang <cjhuang@codeaurora.org>
---
 drivers/net/wireless/ath/ath11k/pci.c | 37 +++++++++++++++++++++++++++++++++++
 1 file changed, 37 insertions(+)

diff --git a/drivers/net/wireless/ath/ath11k/pci.c b/drivers/net/wireless/ath/ath11k/pci.c
index 78478b2..c1ae1df 100644
--- a/drivers/net/wireless/ath/ath11k/pci.c
+++ b/drivers/net/wireless/ath/ath11k/pci.c
@@ -804,6 +804,32 @@ static void ath11k_pci_disable_msi(struct ath11k_pci *ab_pci)
 	pci_free_irq_vectors(ab_pci->pdev);
 }
 
+static int ath11k_pci_config_msi_data(struct ath11k_pci *ab_pci)
+{
+	struct msi_desc *msi_desc;
+	int ret;
+
+	msi_desc = irq_get_msi_desc(ab_pci->pdev->irq);
+	if (!msi_desc) {
+		ath11k_err(ab_pci->ab, "%s msi_desc is NULL!\n", __func__);
+		ret = -EINVAL;
+		goto free_msi_vector;
+	}
+
+	ab_pci->msi_ep_base_data = msi_desc->msg.data;
+
+	ath11k_dbg(ab_pci->ab, ATH11K_DBG_PCI,
+		   "msi base data after request_irq is %d\n",
+		   ab_pci->msi_ep_base_data);
+
+	return 0;
+
+free_msi_vector:
+	pci_free_irq_vectors(ab_pci->pdev);
+
+	return ret;
+}
+
 static int ath11k_pci_claim(struct ath11k_pci *ab_pci, struct pci_dev *pdev)
 {
 	struct ath11k_base *ab = ab_pci->ab;
@@ -1174,6 +1200,17 @@ static int ath11k_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 = ath11k_pci_config_msi_data(ab_pci);
+	if (ret) {
+		ath11k_err(ab, "failed to config msi_data: %d\n", ret);
+		goto err_ce_free;
+	}
+
 	ret = ath11k_core_init(ab);
 	if (ret) {
 		ath11k_err(ab, "failed to init core: %d\n", ret);
-- 
2.7.4