2021-03-30 13:26:40

by Luca Coelho

[permalink] [raw]
Subject: [PATCH 02/12] iwlwifi: pcie: avoid unnecessarily taking spinlock

From: Johannes Berg <[email protected]>

Most devices don't set the apmg_wake_up_wa flag, so we don't do
anything for them. Avoid taking the spinlock for every command
unless the device needs this workaround.

Signed-off-by: Johannes Berg <[email protected]>
Signed-off-by: Luca Coelho <[email protected]>
---
drivers/net/wireless/intel/iwlwifi/pcie/tx.c | 54 +++++++++-----------
1 file changed, 24 insertions(+), 30 deletions(-)

diff --git a/drivers/net/wireless/intel/iwlwifi/pcie/tx.c b/drivers/net/wireless/intel/iwlwifi/pcie/tx.c
index 381e8f90b6f2..ac200e6e941e 100644
--- a/drivers/net/wireless/intel/iwlwifi/pcie/tx.c
+++ b/drivers/net/wireless/intel/iwlwifi/pcie/tx.c
@@ -181,16 +181,20 @@ static void iwl_pcie_clear_cmd_in_flight(struct iwl_trans *trans)
{
struct iwl_trans_pcie *trans_pcie = IWL_TRANS_GET_PCIE_TRANS(trans);

- lockdep_assert_held(&trans_pcie->reg_lock);
-
if (!trans->trans_cfg->base_params->apmg_wake_up_wa)
return;
- if (WARN_ON(!trans_pcie->cmd_hold_nic_awake))
+
+ spin_lock(&trans_pcie->reg_lock);
+
+ if (WARN_ON(!trans_pcie->cmd_hold_nic_awake)) {
+ spin_unlock(&trans_pcie->reg_lock);
return;
+ }

trans_pcie->cmd_hold_nic_awake = false;
__iwl_trans_pcie_clear_bit(trans, CSR_GP_CNTRL,
CSR_GP_CNTRL_REG_FLAG_MAC_ACCESS_REQ);
+ spin_unlock(&trans_pcie->reg_lock);
}

/*
@@ -198,7 +202,6 @@ static void iwl_pcie_clear_cmd_in_flight(struct iwl_trans *trans)
*/
static void iwl_pcie_txq_unmap(struct iwl_trans *trans, int txq_id)
{
- struct iwl_trans_pcie *trans_pcie = IWL_TRANS_GET_PCIE_TRANS(trans);
struct iwl_txq *txq = trans->txqs.txq[txq_id];

if (!txq) {
@@ -222,12 +225,9 @@ static void iwl_pcie_txq_unmap(struct iwl_trans *trans, int txq_id)
iwl_txq_free_tfd(trans, txq);
txq->read_ptr = iwl_txq_inc_wrap(trans, txq->read_ptr);

- if (txq->read_ptr == txq->write_ptr) {
- spin_lock(&trans_pcie->reg_lock);
- if (txq_id == trans->txqs.cmd.q_id)
- iwl_pcie_clear_cmd_in_flight(trans);
- spin_unlock(&trans_pcie->reg_lock);
- }
+ if (txq->read_ptr == txq->write_ptr &&
+ txq_id == trans->txqs.cmd.q_id)
+ iwl_pcie_clear_cmd_in_flight(trans);
}

while (!skb_queue_empty(&txq->overflow_q)) {
@@ -629,22 +629,23 @@ static int iwl_pcie_set_cmd_in_flight(struct iwl_trans *trans,
const struct iwl_host_cmd *cmd)
{
struct iwl_trans_pcie *trans_pcie = IWL_TRANS_GET_PCIE_TRANS(trans);
- int ret;
-
- lockdep_assert_held(&trans_pcie->reg_lock);
+ int ret = 0;

/* Make sure the NIC is still alive in the bus */
if (test_bit(STATUS_TRANS_DEAD, &trans->status))
return -ENODEV;

+ if (!trans->trans_cfg->base_params->apmg_wake_up_wa)
+ return 0;
+
+ spin_lock(&trans_pcie->reg_lock);
/*
* wake up the NIC to make sure that the firmware will see the host
* command - we will let the NIC sleep once all the host commands
* returned. This needs to be done only on NICs that have
- * apmg_wake_up_wa set.
+ * apmg_wake_up_wa set (see above.)
*/
- if (trans->trans_cfg->base_params->apmg_wake_up_wa &&
- !trans_pcie->cmd_hold_nic_awake) {
+ if (!trans_pcie->cmd_hold_nic_awake) {
__iwl_trans_pcie_set_bit(trans, CSR_GP_CNTRL,
CSR_GP_CNTRL_REG_FLAG_MAC_ACCESS_REQ);

@@ -657,12 +658,14 @@ static int iwl_pcie_set_cmd_in_flight(struct iwl_trans *trans,
__iwl_trans_pcie_clear_bit(trans, CSR_GP_CNTRL,
CSR_GP_CNTRL_REG_FLAG_MAC_ACCESS_REQ);
IWL_ERR(trans, "Failed to wake NIC for hcmd\n");
- return -EIO;
+ ret = -EIO;
+ } else {
+ trans_pcie->cmd_hold_nic_awake = true;
}
- trans_pcie->cmd_hold_nic_awake = true;
}
+ spin_unlock(&trans_pcie->reg_lock);

- return 0;
+ return ret;
}

/*
@@ -674,7 +677,6 @@ static int iwl_pcie_set_cmd_in_flight(struct iwl_trans *trans,
*/
static void iwl_pcie_cmdq_reclaim(struct iwl_trans *trans, int txq_id, int idx)
{
- struct iwl_trans_pcie *trans_pcie = IWL_TRANS_GET_PCIE_TRANS(trans);
struct iwl_txq *txq = trans->txqs.txq[txq_id];
int nfreed = 0;
u16 r;
@@ -705,12 +707,8 @@ static void iwl_pcie_cmdq_reclaim(struct iwl_trans *trans, int txq_id, int idx)
}
}

- if (txq->read_ptr == txq->write_ptr) {
- /* BHs are also disabled due to txq->lock */
- spin_lock(&trans_pcie->reg_lock);
+ if (txq->read_ptr == txq->write_ptr)
iwl_pcie_clear_cmd_in_flight(trans);
- spin_unlock(&trans_pcie->reg_lock);
- }

iwl_txq_progress(txq);
}
@@ -914,7 +912,6 @@ void iwl_trans_pcie_txq_disable(struct iwl_trans *trans, int txq_id,
int iwl_pcie_enqueue_hcmd(struct iwl_trans *trans,
struct iwl_host_cmd *cmd)
{
- struct iwl_trans_pcie *trans_pcie = IWL_TRANS_GET_PCIE_TRANS(trans);
struct iwl_txq *txq = trans->txqs.txq[trans->txqs.cmd.q_id];
struct iwl_device_cmd *out_cmd;
struct iwl_cmd_meta *out_meta;
@@ -1160,19 +1157,16 @@ int iwl_pcie_enqueue_hcmd(struct iwl_trans *trans,
if (txq->read_ptr == txq->write_ptr && txq->wd_timeout)
mod_timer(&txq->stuck_timer, jiffies + txq->wd_timeout);

- spin_lock(&trans_pcie->reg_lock);
ret = iwl_pcie_set_cmd_in_flight(trans, cmd);
if (ret < 0) {
idx = ret;
- goto unlock_reg;
+ goto out;
}

/* Increment and update queue's write index */
txq->write_ptr = iwl_txq_inc_wrap(trans, txq->write_ptr);
iwl_pcie_txq_inc_wr_ptr(trans, txq);

- unlock_reg:
- spin_unlock(&trans_pcie->reg_lock);
out:
spin_unlock_bh(&txq->lock);
free_dup_buf:
--
2.31.0