iwlwifi: always copy first 16 bytes of commands
commit 8a964f44e01ad3bbc208c3e80d931ba91b9ea786 upstream.
The FH hardware will always write back to the scratch field
in commands, even host commands not just TX commands, which
can overwrite parts of the command. This is problematic if
the command is re-used (with IWL_HCMD_DFL_NOCOPY) and can
cause calibration issues.
Address this problem by always putting at least the first
16 bytes into the buffer we also use for the command header
and therefore make the DMA engine write back into this.
For commands that are smaller than 16 bytes also always map
enough memory for the DMA engine to write back to.
Reviewed-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
[bwh: Backported to 3.2:
- Adjust context
- Drop the IWL_HCMD_DFL_DUP handling
- Fix descriptor addresses and lengths for tracepoint, but otherwise
leave it unchanged]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
[wujg: Backported to 3.4: adjust context]
Signed-off-by: Jianguo Wu <wujianguo@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/net/wireless/iwlwifi/iwl-trans-pcie-int.h b/drivers/net/wireless/iwlwifi/iwl-trans-pcie-int.h
index dfa0d80..9ae2b49 100644
--- a/drivers/net/wireless/iwlwifi/iwl-trans-pcie-int.h
+++ b/drivers/net/wireless/iwlwifi/iwl-trans-pcie-int.h
@@ -209,6 +209,15 @@
#define TFD_TX_CMD_SLOTS 256
#define TFD_CMD_SLOTS 32
+/*
+ * The FH will write back to the first TB only, so we need
+ * to copy some data into the buffer regardless of whether
+ * it should be mapped or not. This indicates how much to
+ * copy, even for HCMDs it must be big enough to fit the
+ * DRAM scratch from the TX cmd, at least 16 bytes.
+ */
+#define IWL_HCMD_MIN_COPY_SIZE 16
+
struct iwl_tx_queue {
struct iwl_queue q;
struct iwl_tfd *tfds;