2023-11-20 10:16:31

by Kang Yang

Subject: [PATCH 1/7] wifi: ath12k: get msi_data again after request_irq is called

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 <[email protected]>
---
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

2023-11-20 15:52:18

by Jeff Johnson

Subject: Re: [PATCH 1/7] wifi: ath12k: get msi_data again after request_irq is called

On 11/20/2023 2:15 AM, Kang Yang wrote:
> 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 <[email protected]>
Acked-by: Jeff Johnson <[email protected]>