iwlwifi: allow to limit the size of the external buffer for firmware debugging

When we use an external buffer, it is allocated from the
t DRAM and can be as big as 64MB. This buffer is huge and
might not be needed for the specific issue being chased.
Especially if lots of dumps are going to be created.
Allow to limit the size of the buffer in the configuration.

Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>

1 files changed, 23 insertions, 5 deletions

diff --git a/drivers/net/wireless/iwlwifi/pcie/trans.c b/drivers/net/wireless/iwlwifi/pcie/trans.c
index d108e5bef9b7..4526336672c5 100644
--- a/drivers/net/wireless/iwlwifi/pcie/trans.c
+++ b/drivers/net/wireless/iwlwifi/pcie/trans.c
@@ -101,14 +101,26 @@ static void iwl_pcie_free_fw_monitor(struct iwl_trans *trans)
 	trans_pcie->fw_mon_size = 0;
 }
 
-static void iwl_pcie_alloc_fw_monitor(struct iwl_trans *trans)
+static void iwl_pcie_alloc_fw_monitor(struct iwl_trans *trans, u8 max_power)
 {
 	struct iwl_trans_pcie *trans_pcie = IWL_TRANS_GET_PCIE_TRANS(trans);
 	struct page *page = NULL;
 	dma_addr_t phys;
-	u32 size;
+	u32 size = 0;
 	u8 power;
 
+	if (!max_power) {
+		/* default max_power is maximum */
+		max_power = 26;
+	} else {
+		max_power += 11;
+	}
+
+	if (WARN(max_power > 26,
+		 "External buffer size for monitor is too big %d, check the FW TLV\n",
+		 max_power))
+		return;
+
 	if (trans_pcie->fw_mon_page) {
 		dma_sync_single_for_device(trans->dev, trans_pcie->fw_mon_phys,
 					   trans_pcie->fw_mon_size,
@@ -117,7 +129,7 @@ static void iwl_pcie_alloc_fw_monitor(struct iwl_trans *trans)
 	}
 
 	phys = 0;
-	for (power = 26; power >= 11; power--) {
+	for (power = max_power; power >= 11; power--) {
 		int order;
 
 		size = BIT(power);
@@ -143,6 +155,12 @@ static void iwl_pcie_alloc_fw_monitor(struct iwl_trans *trans)
 	if (WARN_ON_ONCE(!page))
 		return;
 
+	if (power != max_power)
+		IWL_ERR(trans,
+			"Sorry - debug buffer is only %luK while you requested %luK\n",
+			(unsigned long)BIT(power - 10),
+			(unsigned long)BIT(max_power - 10));
+
 	trans_pcie->fw_mon_page = page;
 	trans_pcie->fw_mon_phys = phys;
 	trans_pcie->fw_mon_size = size;
@@ -834,7 +852,7 @@ static void iwl_pcie_apply_destination(struct iwl_trans *trans)
 		 get_fw_dbg_mode_string(dest->monitor_mode));
 
 	if (dest->monitor_mode == EXTERNAL_MODE)
-		iwl_pcie_alloc_fw_monitor(trans);
+		iwl_pcie_alloc_fw_monitor(trans, dest->size_power);
 	else
 		IWL_WARN(trans, "PCI should have external buffer debug\n");
 
@@ -908,7 +926,7 @@ static int iwl_pcie_load_given_ucode(struct iwl_trans *trans,
 	/* supported for 7000 only for the moment */
 	if (iwlwifi_mod_params.fw_monitor &&
 	    trans->cfg->device_family == IWL_DEVICE_FAMILY_7000) {
-		iwl_pcie_alloc_fw_monitor(trans);
+		iwl_pcie_alloc_fw_monitor(trans, 0);
 
 		if (trans_pcie->fw_mon_size) {
 			iwl_write_prph(trans, MON_BUFF_BASE_ADDR,