iwlwifi: get the correct HCMD in the response handler

Until now, the response handler of a Host Command got the
exact same pointer that was also given to the DMA engine.
We almost never need to the Host Command that was sent while
handling its response, but when we do need it, we see that
the command has been modified.

This mystery has been elucidated. The FH (our DMA engine)
writes its meta data on the buffer in the DRAM. Of course it
copies the buffer to the NIC first. This was known to happen
for Tx command, but as a matter of fact, it happens to all
TFD brought by the FH which doesn't care much about what it
brings from DRAM to internal SRAM.

So copy the Host Command to yet another buffer so that we
can properly pass the buffer that was sent originally to the
fw. Do that only if it was request by the user since very
few flows need to get the HCMD sent in the response handler.

Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

1 files changed, 8 insertions, 2 deletions

diff --git a/drivers/net/wireless/iwlwifi/iwl-trans.h b/drivers/net/wireless/iwlwifi/iwl-trans.h
index 8ac72a6ef227..ff1154232885 100644
--- a/drivers/net/wireless/iwlwifi/iwl-trans.h
+++ b/drivers/net/wireless/iwlwifi/iwl-trans.h
@@ -184,14 +184,20 @@ struct iwl_rx_packet {
  * @CMD_SYNC: The caller will be stalled until the fw responds to the command
  * @CMD_ASYNC: Return right away and don't want for the response
  * @CMD_WANT_SKB: valid only with CMD_SYNC. The caller needs the buffer of the
- *	response.
+ *	response. The caller needs to call iwl_free_resp when done.
+ * @CMD_WANT_HCMD: The caller needs to get the HCMD that was sent in the
+ *	response handler. Chunks flagged by %IWL_HCMD_DFL_NOCOPY won't be
+ *	copied. The pointer passed to the response handler is in the transport
+ *	ownership and don't need to be freed by the op_mode. This also means
+ *	that the pointer is invalidated after the op_mode's handler returns.
  * @CMD_ON_DEMAND: This command is sent by the test mode pipe.
  */
 enum CMD_MODE {
 	CMD_SYNC = 0,
 	CMD_ASYNC = BIT(0),
 	CMD_WANT_SKB = BIT(1),
-	CMD_ON_DEMAND = BIT(2),
+	CMD_WANT_HCMD = BIT(2),
+	CMD_ON_DEMAND = BIT(3),
 };
 
 #define DEF_CMD_PAYLOAD_SIZE 320