[PATCH net-next 0/4] sfc: add MCDI tracing

[PATCH net-next 0/4] sfc: add MCDI tracing

[Edward Cree]

This patchset adds support for logging Management-Controller-to-Driver Interface interactions between the sfc driver and a bound device, to aid in debugging.
Solarflare has a tool to decode the resulting traces and will look to open-source this if there is any external interest, but the protocol is already detailed in drivers/net/ethernet/sfc/mcdi_pcol.h.

Edward Cree (3):
  sfc: add tracing of MCDI commands
  sfc: add sysfs entry to control MCDI tracing
  sfc: add module parameter to enable MCDI logging on new functions

Jon Cooper (1):
  sfc: Initialise MCDI buffers to 0 on declaration.

 drivers/net/ethernet/sfc/Kconfig |   9 ++++
 drivers/net/ethernet/sfc/ef10.c  |  27 ++++++----
 drivers/net/ethernet/sfc/efx.c   |  49 +++++++++++++++---
 drivers/net/ethernet/sfc/mcdi.c  | 107 ++++++++++++++++++++++++++++++++++++---
 drivers/net/ethernet/sfc/mcdi.h  |  14 +++--
 drivers/net/ethernet/sfc/ptp.c   |   6 +--
 6 files changed, 180 insertions(+), 32 deletions(-)

[PATCH net-next 1/4] sfc: add tracing of MCDI commands

[Edward Cree]

MCDI tracing is conditional on CONFIG_SFC_MCDI_LOGGING, which is enabled
 by default.

Each MCDI command will produce a console line like
    sfc dom:bus:dev:fn ifname: MCDI RPC REQ: xxxxxxxx [yyyyyyyy...]
where xxxxxxxx etc. are the raw MCDI payload in 32-bit hex chunks.
The response will then produce a similar line with "RESP" instead of "REQ",
 and containing the MCDI response payload (if any).

Signed-off-by: Edward Cree <ecree@solarflare.com>
---
 drivers/net/ethernet/sfc/Kconfig |  8 ++++
 drivers/net/ethernet/sfc/ef10.c  |  3 ++
 drivers/net/ethernet/sfc/mcdi.c  | 90 ++++++++++++++++++++++++++++++++++++++--
 drivers/net/ethernet/sfc/mcdi.h  |  4 ++
 4 files changed, 101 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ethernet/sfc/Kconfig b/drivers/net/ethernet/sfc/Kconfig
index 0889212..c4ba42b 100644
--- a/drivers/net/ethernet/sfc/Kconfig
+++ b/drivers/net/ethernet/sfc/Kconfig
@@ -36,3 +36,11 @@ config SFC_SRIOV
 	  This enables support for the SFC9000 I/O Virtualization
 	  features, allowing accelerated network performance in
 	  virtualized environments.
+config SFC_MCDI_LOGGING
+	bool "Solarflare SFC9000/SFC9100-family MCDI logging support"
+	depends on SFC
+	default y
+	---help---
+	  This enables support for tracing of MCDI (Management-Controller-to-
+	  Driver-Interface) commands and responses, allowing debugging of
+	  driver/firmware interaction.
diff --git a/drivers/net/ethernet/sfc/ef10.c b/drivers/net/ethernet/sfc/ef10.c
index 882117a..2e8e5de 100644
--- a/drivers/net/ethernet/sfc/ef10.c
+++ b/drivers/net/ethernet/sfc/ef10.c
@@ -219,6 +219,9 @@ static int efx_ef10_probe(struct efx_nic *efx)
 		return -ENOMEM;
 	efx->nic_data = nic_data;
 
+	/* we assume later that we can copy from this buffer in dwords */
+	BUILD_BUG_ON(MCDI_CTL_SDU_LEN_MAX_V2 % 4);
+
 	rc = efx_nic_alloc_buffer(efx, &nic_data->mcdi_buf,
 				  8 + MCDI_CTL_SDU_LEN_MAX_V2, GFP_KERNEL);
 	if (rc)
diff --git a/drivers/net/ethernet/sfc/mcdi.c b/drivers/net/ethernet/sfc/mcdi.c
index b44ee31..255a246 100644
--- a/drivers/net/ethernet/sfc/mcdi.c
+++ b/drivers/net/ethernet/sfc/mcdi.c
@@ -58,14 +58,20 @@ int efx_mcdi_init(struct efx_nic *efx)
 {
 	struct efx_mcdi_iface *mcdi;
 	bool already_attached;
-	int rc;
+	int rc = -ENOMEM;
 
 	efx->mcdi = kzalloc(sizeof(*efx->mcdi), GFP_KERNEL);
 	if (!efx->mcdi)
-		return -ENOMEM;
+		goto fail;
 
 	mcdi = efx_mcdi(efx);
 	mcdi->efx = efx;
+#ifdef CONFIG_SFC_MCDI_LOGGING
+	/* consuming code assumes buffer is page-sized */
+	mcdi->logging_buffer = (char *)__get_free_page(GFP_KERNEL);
+	if (!mcdi->logging_buffer)
+		goto fail1;
+#endif
 	init_waitqueue_head(&mcdi->wq);
 	spin_lock_init(&mcdi->iface_lock);
 	mcdi->state = MCDI_STATE_QUIESCENT;
@@ -81,7 +87,7 @@ int efx_mcdi_init(struct efx_nic *efx)
 	/* Recover from a failed assertion before probing */
 	rc = efx_mcdi_handle_assertion(efx);
 	if (rc)
-		return rc;
+		goto fail2;
 
 	/* Let the MC (and BMC, if this is a LOM) know that the driver
 	 * is loaded. We should do this before we reset the NIC.
@@ -90,7 +96,7 @@ int efx_mcdi_init(struct efx_nic *efx)
 	if (rc) {
 		netif_err(efx, probe, efx->net_dev,
 			  "Unable to register driver with MCPU\n");
-		return rc;
+		goto fail2;
 	}
 	if (already_attached)
 		/* Not a fatal error */
@@ -102,6 +108,15 @@ int efx_mcdi_init(struct efx_nic *efx)
 		efx->primary = efx;
 
 	return 0;
+fail2:
+#ifdef CONFIG_SFC_MCDI_LOGGING
+	free_page((unsigned long)mcdi->logging_buffer);
+fail1:
+#endif
+	kfree(efx->mcdi);
+	efx->mcdi = NULL;
+fail:
+	return rc;
 }
 
 void efx_mcdi_fini(struct efx_nic *efx)
@@ -114,6 +129,10 @@ void efx_mcdi_fini(struct efx_nic *efx)
 	/* Relinquish the device (back to the BMC, if this is a LOM) */
 	efx_mcdi_drv_attach(efx, false, NULL);
 
+#ifdef CONFIG_SFC_MCDI_LOGGING
+	free_page((unsigned long)efx->mcdi->iface.logging_buffer);
+#endif
+
 	kfree(efx->mcdi);
 }
 
@@ -121,6 +140,9 @@ static void efx_mcdi_send_request(struct efx_nic *efx, unsigned cmd,
 				  const efx_dword_t *inbuf, size_t inlen)
 {
 	struct efx_mcdi_iface *mcdi = efx_mcdi(efx);
+#ifdef CONFIG_SFC_MCDI_LOGGING
+	char *buf = mcdi->logging_buffer; /* page-sized */
+#endif
 	efx_dword_t hdr[2];
 	size_t hdr_len;
 	u32 xflags, seqno;
@@ -165,6 +187,31 @@ static void efx_mcdi_send_request(struct efx_nic *efx, unsigned cmd,
 		hdr_len = 8;
 	}
 
+#ifdef CONFIG_SFC_MCDI_LOGGING
+	if (!WARN_ON_ONCE(!buf)) {
+		int bytes = 0;
+		int i;
+		/* Lengths should always be a whole number of dwords, so scream
+		 * if they're not.
+		 */
+		WARN_ON_ONCE(hdr_len % 4);
+		WARN_ON_ONCE(inlen % 4);
+
+		/* We own the logging buffer, as only one MCDI can be in
+		 * progress on a NIC at any one time.  So no need for locking.
+		 */
+		for (i = 0; i < hdr_len / 4 && bytes < PAGE_SIZE; i++)
+			bytes += snprintf(buf + bytes, PAGE_SIZE - bytes,
+					  " %08x", le32_to_cpu(hdr[i].u32[0]));
+
+		for (i = 0; i < inlen / 4 && bytes < PAGE_SIZE; i++)
+			bytes += snprintf(buf + bytes, PAGE_SIZE - bytes,
+					  " %08x", le32_to_cpu(inbuf[i].u32[0]));
+
+		netif_info(efx, hw, efx->net_dev, "MCDI RPC REQ:%s\n", buf);
+	}
+#endif
+
 	efx->type->mcdi_request(efx, hdr, hdr_len, inbuf, inlen);
 
 	mcdi->new_epoch = false;
@@ -206,6 +253,9 @@ static void efx_mcdi_read_response_header(struct efx_nic *efx)
 {
 	struct efx_mcdi_iface *mcdi = efx_mcdi(efx);
 	unsigned int respseq, respcmd, error;
+#ifdef CONFIG_SFC_MCDI_LOGGING
+	char *buf = mcdi->logging_buffer; /* page-sized */
+#endif
 	efx_dword_t hdr;
 
 	efx->type->mcdi_read_response(efx, &hdr, 0, 4);
@@ -223,6 +273,38 @@ static void efx_mcdi_read_response_header(struct efx_nic *efx)
 			EFX_DWORD_FIELD(hdr, MC_CMD_V2_EXTN_IN_ACTUAL_LEN);
 	}
 
+#ifdef CONFIG_SFC_MCDI_LOGGING
+	if (!WARN_ON_ONCE(!buf)) {
+		size_t hdr_len, data_len;
+		int bytes = 0;
+		int i;
+
+		WARN_ON_ONCE(mcdi->resp_hdr_len % 4);
+		hdr_len = mcdi->resp_hdr_len / 4;
+		/* MCDI_DECLARE_BUF ensures that underlying buffer is padded
+		 * to dword size, and the MCDI buffer is always dword size */
+		data_len = DIV_ROUND_UP(mcdi->resp_data_len, 4);
+
+		/* We own the logging buffer, as only one MCDI can be in
+		 * progress on a NIC at any one time.  So no need for locking.
+		 */
+		for (i = 0; i < hdr_len && bytes < PAGE_SIZE; i++) {
+			efx->type->mcdi_read_response(efx, &hdr, (i * 4), 4);
+			bytes += snprintf(buf + bytes, PAGE_SIZE - bytes,
+					  " %08x", le32_to_cpu(hdr.u32[0]));
+		}
+
+		for (i = 0; i < data_len && bytes < PAGE_SIZE; i++) {
+			efx->type->mcdi_read_response(efx, &hdr,
+					mcdi->resp_hdr_len + (i * 4), 4);
+			bytes += snprintf(buf + bytes, PAGE_SIZE - bytes,
+					  " %08x", le32_to_cpu(hdr.u32[0]));
+		}
+
+		netif_info(efx, hw, efx->net_dev, "MCDI RPC RESP:%s\n", buf);
+	}
+#endif
+
 	if (error && mcdi->resp_data_len == 0) {
 		netif_err(efx, hw, efx->net_dev, "MC rebooted\n");
 		mcdi->resprc = -EIO;
diff --git a/drivers/net/ethernet/sfc/mcdi.h b/drivers/net/ethernet/sfc/mcdi.h
index 5df1e98..2f6f032 100644
--- a/drivers/net/ethernet/sfc/mcdi.h
+++ b/drivers/net/ethernet/sfc/mcdi.h
@@ -58,6 +58,7 @@ enum efx_mcdi_mode {
  *	enabled
  * @async_list: Queue of asynchronous requests
  * @async_timer: Timer for asynchronous request timeout
+ * @logging_buffer: buffer that may be used to build MCDI tracing messages
  */
 struct efx_mcdi_iface {
 	struct efx_nic *efx;
@@ -74,6 +75,9 @@ struct efx_mcdi_iface {
 	spinlock_t async_lock;
 	struct list_head async_list;
 	struct timer_list async_timer;
+#ifdef CONFIG_SFC_MCDI_LOGGING
+	char *logging_buffer;
+#endif
 };
 
 struct efx_mcdi_mon {

[PATCH net-next 2/4] sfc: add sysfs entry to control MCDI tracing

[Edward Cree]

MCDI tracing is enabled per-function with a sysfs file
    /sys/class/net/<NET_DEV>/device/mcdi_logging

Signed-off-by: Edward Cree <ecree@solarflare.com>
---
 drivers/net/ethernet/sfc/Kconfig |  3 ++-
 drivers/net/ethernet/sfc/efx.c   | 49 ++++++++++++++++++++++++++++++++++------
 drivers/net/ethernet/sfc/mcdi.c  |  4 ++--
 drivers/net/ethernet/sfc/mcdi.h  |  2 ++
 4 files changed, 48 insertions(+), 10 deletions(-)

diff --git a/drivers/net/ethernet/sfc/Kconfig b/drivers/net/ethernet/sfc/Kconfig
index c4ba42b..4dd92b7 100644
--- a/drivers/net/ethernet/sfc/Kconfig
+++ b/drivers/net/ethernet/sfc/Kconfig
@@ -43,4 +43,5 @@ config SFC_MCDI_LOGGING
 	---help---
 	  This enables support for tracing of MCDI (Management-Controller-to-
 	  Driver-Interface) commands and responses, allowing debugging of
-	  driver/firmware interaction.
+	  driver/firmware interaction.  The tracing is actually enabled by
+	  a sysfs file 'mcdi_logging' under the PCI device.
diff --git a/drivers/net/ethernet/sfc/efx.c b/drivers/net/ethernet/sfc/efx.c
index 0f127a0..86a2da5 100644
--- a/drivers/net/ethernet/sfc/efx.c
+++ b/drivers/net/ethernet/sfc/efx.c
@@ -2298,6 +2298,28 @@ show_phy_type(struct device *dev, struct device_attribute *attr, char *buf)
 }
 static DEVICE_ATTR(phy_type, 0444, show_phy_type, NULL);
 
+#ifdef CONFIG_SFC_MCDI_LOGGING
+static ssize_t show_mcdi_log(struct device *dev, struct device_attribute *attr,
+			     char *buf)
+{
+	struct efx_nic *efx = pci_get_drvdata(to_pci_dev(dev));
+	struct efx_mcdi_iface *mcdi = efx_mcdi(efx);
+
+	return scnprintf(buf, PAGE_SIZE, "%d\n", mcdi->logging_enabled);
+}
+static ssize_t set_mcdi_log(struct device *dev, struct device_attribute *attr,
+			    const char *buf, size_t count)
+{
+	struct efx_nic *efx = pci_get_drvdata(to_pci_dev(dev));
+	struct efx_mcdi_iface *mcdi = efx_mcdi(efx);
+	bool enable = count > 0 && *buf != '0';
+
+	mcdi->logging_enabled = enable;
+	return count;
+}
+static DEVICE_ATTR(mcdi_logging, 0644, show_mcdi_log, set_mcdi_log);
+#endif
+
 static int efx_register_netdev(struct efx_nic *efx)
 {
 	struct net_device *net_dev = efx->net_dev;
@@ -2355,9 +2377,21 @@ static int efx_register_netdev(struct efx_nic *efx)
 			  "failed to init net dev attributes\n");
 		goto fail_registered;
 	}
+#ifdef CONFIG_SFC_MCDI_LOGGING
+	rc = device_create_file(&efx->pci_dev->dev, &dev_attr_mcdi_logging);
+	if (rc) {
+		netif_err(efx, drv, efx->net_dev,
+			  "failed to init net dev attributes\n");
+		goto fail_attr_mcdi_logging;
+	}
+#endif
 
 	return 0;
 
+#ifdef CONFIG_SFC_MCDI_LOGGING
+fail_attr_mcdi_logging:
+	device_remove_file(&efx->pci_dev->dev, &dev_attr_phy_type);
+#endif
 fail_registered:
 	rtnl_lock();
 	efx_dissociate(efx);
@@ -2376,13 +2410,14 @@ static void efx_unregister_netdev(struct efx_nic *efx)
 
 	BUG_ON(netdev_priv(efx->net_dev) != efx);
 
-	strlcpy(efx->name, pci_name(efx->pci_dev), sizeof(efx->name));
-	device_remove_file(&efx->pci_dev->dev, &dev_attr_phy_type);
-
-	rtnl_lock();
-	unregister_netdevice(efx->net_dev);
-	efx->state = STATE_UNINIT;
-	rtnl_unlock();
+	if (efx_dev_registered(efx)) {
+		strlcpy(efx->name, pci_name(efx->pci_dev), sizeof(efx->name));
+#ifdef CONFIG_SFC_MCDI_LOGGING
+		device_remove_file(&efx->pci_dev->dev, &dev_attr_mcdi_logging);
+#endif
+		device_remove_file(&efx->pci_dev->dev, &dev_attr_phy_type);
+		unregister_netdev(efx->net_dev);
+	}
 }
 
 /**************************************************************************
diff --git a/drivers/net/ethernet/sfc/mcdi.c b/drivers/net/ethernet/sfc/mcdi.c
index 255a246..a147bfc 100644
--- a/drivers/net/ethernet/sfc/mcdi.c
+++ b/drivers/net/ethernet/sfc/mcdi.c
@@ -188,7 +188,7 @@ static void efx_mcdi_send_request(struct efx_nic *efx, unsigned cmd,
 	}
 
 #ifdef CONFIG_SFC_MCDI_LOGGING
-	if (!WARN_ON_ONCE(!buf)) {
+	if (mcdi->logging_enabled && !WARN_ON_ONCE(!buf)) {
 		int bytes = 0;
 		int i;
 		/* Lengths should always be a whole number of dwords, so scream
@@ -274,7 +274,7 @@ static void efx_mcdi_read_response_header(struct efx_nic *efx)
 	}
 
 #ifdef CONFIG_SFC_MCDI_LOGGING
-	if (!WARN_ON_ONCE(!buf)) {
+	if (mcdi->logging_enabled && !WARN_ON_ONCE(!buf)) {
 		size_t hdr_len, data_len;
 		int bytes = 0;
 		int i;
diff --git a/drivers/net/ethernet/sfc/mcdi.h b/drivers/net/ethernet/sfc/mcdi.h
index 2f6f032..47035a0 100644
--- a/drivers/net/ethernet/sfc/mcdi.h
+++ b/drivers/net/ethernet/sfc/mcdi.h
@@ -59,6 +59,7 @@ enum efx_mcdi_mode {
  * @async_list: Queue of asynchronous requests
  * @async_timer: Timer for asynchronous request timeout
  * @logging_buffer: buffer that may be used to build MCDI tracing messages
+ * @logging_enabled: whether to trace MCDI
  */
 struct efx_mcdi_iface {
 	struct efx_nic *efx;
@@ -77,6 +78,7 @@ struct efx_mcdi_iface {
 	struct timer_list async_timer;
 #ifdef CONFIG_SFC_MCDI_LOGGING
 	char *logging_buffer;
+	bool logging_enabled;
 #endif
 };
 

[PATCH net-next 3/4] sfc: add module parameter to enable MCDI logging on new functions

[Edward Cree]

As many issues are encountered at probe time, where MCDI logging can't be
 enabled through the sysfs node, this change adds a module parameter
 'mcdi_logging_default', which defaults to false.  When set to true, newly-
 probed functions will have MCDI logging enabled.  The setting can
 subsequently be changed as normal through the sysfs node.

Signed-off-by: Edward Cree <ecree@solarflare.com>
---
 drivers/net/ethernet/sfc/mcdi.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/net/ethernet/sfc/mcdi.c b/drivers/net/ethernet/sfc/mcdi.c
index a147bfc..50b8ff8 100644
--- a/drivers/net/ethernet/sfc/mcdi.c
+++ b/drivers/net/ethernet/sfc/mcdi.c
@@ -8,6 +8,7 @@
  */
 
 #include <linux/delay.h>
+#include <linux/moduleparam.h>
 #include <asm/cmpxchg.h>
 #include "net_driver.h"
 #include "nic.h"
@@ -54,6 +55,13 @@ static int efx_mcdi_drv_attach(struct efx_nic *efx, bool driver_operating,
 static bool efx_mcdi_poll_once(struct efx_nic *efx);
 static void efx_mcdi_abandon(struct efx_nic *efx);
 
+#ifdef CONFIG_SFC_MCDI_LOGGING
+static bool mcdi_logging_default;
+module_param(mcdi_logging_default, bool, 0644);
+MODULE_PARM_DESC(mcdi_logging_default,
+		 "Enable MCDI logging on newly-probed functions");
+#endif
+
 int efx_mcdi_init(struct efx_nic *efx)
 {
 	struct efx_mcdi_iface *mcdi;
@@ -71,6 +79,7 @@ int efx_mcdi_init(struct efx_nic *efx)
 	mcdi->logging_buffer = (char *)__get_free_page(GFP_KERNEL);
 	if (!mcdi->logging_buffer)
 		goto fail1;
+	mcdi->logging_enabled = mcdi_logging_default;
 #endif
 	init_waitqueue_head(&mcdi->wq);
 	spin_lock_init(&mcdi->iface_lock);

[PATCH net-next 4/4] sfc: Initialise MCDI buffers to 0 on declaration.

[Edward Cree]

From: Jon Cooper <jcooper@solarflare.com>

Signed-off-by: Edward Cree <ecree@solarflare.com>
---
 drivers/net/ethernet/sfc/ef10.c | 24 +++++++++++++-----------
 drivers/net/ethernet/sfc/mcdi.c |  8 ++++----
 drivers/net/ethernet/sfc/mcdi.h |  8 +++++---
 drivers/net/ethernet/sfc/ptp.c  |  6 +++---
 4 files changed, 25 insertions(+), 21 deletions(-)

diff --git a/drivers/net/ethernet/sfc/ef10.c b/drivers/net/ethernet/sfc/ef10.c
index 2e8e5de..ed0ec88 100644
--- a/drivers/net/ethernet/sfc/ef10.c
+++ b/drivers/net/ethernet/sfc/ef10.c
@@ -350,7 +350,7 @@ static int efx_ef10_probe_vf(struct efx_nic *efx __attribute__ ((unused)))
 
 static int efx_ef10_free_vis(struct efx_nic *efx)
 {
-	MCDI_DECLARE_BUF_OUT_OR_ERR(outbuf, 0);
+	MCDI_DECLARE_BUF_ERR(outbuf);
 	size_t outlen;
 	int rc = efx_mcdi_rpc_quiet(efx, MC_CMD_FREE_VIS, NULL, 0,
 				    outbuf, sizeof(outbuf), &outlen);
@@ -421,7 +421,7 @@ static int efx_ef10_alloc_piobufs(struct efx_nic *efx, unsigned int n)
 static int efx_ef10_link_piobufs(struct efx_nic *efx)
 {
 	struct efx_ef10_nic_data *nic_data = efx->nic_data;
-	MCDI_DECLARE_BUF(inbuf,
+	_MCDI_DECLARE_BUF(inbuf,
 			 max(MC_CMD_LINK_PIOBUF_IN_LEN,
 			     MC_CMD_UNLINK_PIOBUF_IN_LEN));
 	struct efx_channel *channel;
@@ -432,6 +432,8 @@ static int efx_ef10_link_piobufs(struct efx_nic *efx)
 	BUILD_BUG_ON(MC_CMD_LINK_PIOBUF_OUT_LEN != 0);
 	BUILD_BUG_ON(MC_CMD_UNLINK_PIOBUF_OUT_LEN != 0);
 
+	memset(inbuf, 0, sizeof(inbuf));
+
 	/* Link a buffer to each VI in the write-combining mapping */
 	for (index = 0; index < nic_data->n_piobufs; ++index) {
 		MCDI_SET_DWORD(inbuf, LINK_PIOBUF_IN_PIOBUF_HANDLE,
@@ -1315,17 +1317,17 @@ static void efx_ef10_tx_init(struct efx_tx_queue *tx_queue)
 {
 	MCDI_DECLARE_BUF(inbuf, MC_CMD_INIT_TXQ_IN_LEN(EFX_MAX_DMAQ_SIZE * 8 /
 						       EFX_BUF_SIZE));
-	MCDI_DECLARE_BUF(outbuf, MC_CMD_INIT_TXQ_OUT_LEN);
 	bool csum_offload = tx_queue->queue & EFX_TXQ_TYPE_OFFLOAD;
 	size_t entries = tx_queue->txd.buf.len / EFX_BUF_SIZE;
 	struct efx_channel *channel = tx_queue->channel;
 	struct efx_nic *efx = tx_queue->efx;
 	struct efx_ef10_nic_data *nic_data = efx->nic_data;
-	size_t inlen, outlen;
+	size_t inlen;
 	dma_addr_t dma_addr;
 	efx_qword_t *txd;
 	int rc;
 	int i;
+	BUILD_BUG_ON(MC_CMD_INIT_TXQ_OUT_LEN != 0);
 
 	MCDI_SET_DWORD(inbuf, INIT_TXQ_IN_SIZE, tx_queue->ptr_mask + 1);
 	MCDI_SET_DWORD(inbuf, INIT_TXQ_IN_TARGET_EVQ, channel->channel);
@@ -1350,7 +1352,7 @@ static void efx_ef10_tx_init(struct efx_tx_queue *tx_queue)
 	inlen = MC_CMD_INIT_TXQ_IN_LEN(entries);
 
 	rc = efx_mcdi_rpc(efx, MC_CMD_INIT_TXQ, inbuf, inlen,
-			  outbuf, sizeof(outbuf), &outlen);
+			  NULL, 0, NULL);
 	if (rc)
 		goto fail;
 
@@ -1383,7 +1385,7 @@ fail:
 static void efx_ef10_tx_fini(struct efx_tx_queue *tx_queue)
 {
 	MCDI_DECLARE_BUF(inbuf, MC_CMD_FINI_TXQ_IN_LEN);
-	MCDI_DECLARE_BUF(outbuf, MC_CMD_FINI_TXQ_OUT_LEN);
+	MCDI_DECLARE_BUF_ERR(outbuf);
 	struct efx_nic *efx = tx_queue->efx;
 	size_t outlen;
 	int rc;
@@ -1690,15 +1692,15 @@ static void efx_ef10_rx_init(struct efx_rx_queue *rx_queue)
 	MCDI_DECLARE_BUF(inbuf,
 			 MC_CMD_INIT_RXQ_IN_LEN(EFX_MAX_DMAQ_SIZE * 8 /
 						EFX_BUF_SIZE));
-	MCDI_DECLARE_BUF(outbuf, MC_CMD_INIT_RXQ_OUT_LEN);
 	struct efx_channel *channel = efx_rx_queue_channel(rx_queue);
 	size_t entries = rx_queue->rxd.buf.len / EFX_BUF_SIZE;
 	struct efx_nic *efx = rx_queue->efx;
 	struct efx_ef10_nic_data *nic_data = efx->nic_data;
-	size_t inlen, outlen;
+	size_t inlen;
 	dma_addr_t dma_addr;
 	int rc;
 	int i;
+	BUILD_BUG_ON(MC_CMD_INIT_RXQ_OUT_LEN != 0);
 
 	rx_queue->scatter_n = 0;
 	rx_queue->scatter_len = 0;
@@ -1727,7 +1729,7 @@ static void efx_ef10_rx_init(struct efx_rx_queue *rx_queue)
 	inlen = MC_CMD_INIT_RXQ_IN_LEN(entries);
 
 	rc = efx_mcdi_rpc(efx, MC_CMD_INIT_RXQ, inbuf, inlen,
-			  outbuf, sizeof(outbuf), &outlen);
+			  NULL, 0, NULL);
 	if (rc)
 		netdev_WARN(efx->net_dev, "failed to initialise RXQ %d\n",
 			    efx_rx_queue_index(rx_queue));
@@ -1736,7 +1738,7 @@ static void efx_ef10_rx_init(struct efx_rx_queue *rx_queue)
 static void efx_ef10_rx_fini(struct efx_rx_queue *rx_queue)
 {
 	MCDI_DECLARE_BUF(inbuf, MC_CMD_FINI_RXQ_IN_LEN);
-	MCDI_DECLARE_BUF(outbuf, MC_CMD_FINI_RXQ_OUT_LEN);
+	MCDI_DECLARE_BUF_ERR(outbuf);
 	struct efx_nic *efx = rx_queue->efx;
 	size_t outlen;
 	int rc;
@@ -1898,7 +1900,7 @@ static int efx_ef10_ev_init(struct efx_channel *channel)
 static void efx_ef10_ev_fini(struct efx_channel *channel)
 {
 	MCDI_DECLARE_BUF(inbuf, MC_CMD_FINI_EVQ_IN_LEN);
-	MCDI_DECLARE_BUF(outbuf, MC_CMD_FINI_EVQ_OUT_LEN);
+	MCDI_DECLARE_BUF_ERR(outbuf);
 	struct efx_nic *efx = channel->efx;
 	size_t outlen;
 	int rc;
diff --git a/drivers/net/ethernet/sfc/mcdi.c b/drivers/net/ethernet/sfc/mcdi.c
index 50b8ff8..448089a 100644
--- a/drivers/net/ethernet/sfc/mcdi.c
+++ b/drivers/net/ethernet/sfc/mcdi.c
@@ -497,7 +497,7 @@ static bool efx_mcdi_complete_async(struct efx_mcdi_iface *mcdi, bool timeout)
 	struct efx_mcdi_async_param *async;
 	size_t hdr_len, data_len, err_len;
 	efx_dword_t *outbuf;
-	MCDI_DECLARE_BUF_OUT_OR_ERR(errbuf, 0);
+	MCDI_DECLARE_BUF_ERR(errbuf);
 	int rc;
 
 	if (cmpxchg(&mcdi->state,
@@ -625,7 +625,7 @@ static int _efx_mcdi_rpc_finish(struct efx_nic *efx, unsigned cmd, size_t inlen,
 				size_t *outlen_actual, bool quiet)
 {
 	struct efx_mcdi_iface *mcdi = efx_mcdi(efx);
-	MCDI_DECLARE_BUF_OUT_OR_ERR(errbuf, 0);
+	MCDI_DECLARE_BUF_ERR(errbuf);
 	int rc;
 
 	if (mcdi->mode == MCDI_MODE_POLL)
@@ -1480,7 +1480,7 @@ fail1:
 static int efx_mcdi_read_assertion(struct efx_nic *efx)
 {
 	MCDI_DECLARE_BUF(inbuf, MC_CMD_GET_ASSERTS_IN_LEN);
-	MCDI_DECLARE_BUF_OUT_OR_ERR(outbuf, MC_CMD_GET_ASSERTS_OUT_LEN);
+	MCDI_DECLARE_BUF(outbuf, MC_CMD_GET_ASSERTS_OUT_LEN);
 	unsigned int flags, index;
 	const char *reason;
 	size_t outlen;
@@ -1790,7 +1790,7 @@ int efx_mcdi_set_workaround(struct efx_nic *efx, u32 type, bool enabled)
 int efx_mcdi_get_workarounds(struct efx_nic *efx, unsigned int *impl_out,
 			     unsigned int *enabled_out)
 {
-	MCDI_DECLARE_BUF_OUT_OR_ERR(outbuf, MC_CMD_GET_WORKAROUNDS_OUT_LEN);
+	MCDI_DECLARE_BUF(outbuf, MC_CMD_GET_WORKAROUNDS_OUT_LEN);
 	size_t outlen;
 	int rc;
 
diff --git a/drivers/net/ethernet/sfc/mcdi.h b/drivers/net/ethernet/sfc/mcdi.h
index 47035a0..1838afe 100644
--- a/drivers/net/ethernet/sfc/mcdi.h
+++ b/drivers/net/ethernet/sfc/mcdi.h
@@ -182,10 +182,12 @@ void efx_mcdi_sensor_event(struct efx_nic *efx, efx_qword_t *ev);
  * 32-bit-aligned.  Also, on Siena we must copy to the MC shared
  * memory strictly 32 bits at a time, so add any necessary padding.
  */
-#define MCDI_DECLARE_BUF(_name, _len)					\
+#define _MCDI_DECLARE_BUF(_name, _len)					\
 	efx_dword_t _name[DIV_ROUND_UP(_len, 4)]
-#define MCDI_DECLARE_BUF_OUT_OR_ERR(_name, _len)			\
-	MCDI_DECLARE_BUF(_name, max_t(size_t, _len, 8))
+#define MCDI_DECLARE_BUF(_name, _len)					\
+	_MCDI_DECLARE_BUF(_name, _len) = {{{0}}}
+#define MCDI_DECLARE_BUF_ERR(_name)					\
+	MCDI_DECLARE_BUF(_name, 8)
 #define _MCDI_PTR(_buf, _offset)					\
 	((u8 *)(_buf) + (_offset))
 #define MCDI_PTR(_buf, _field)						\
diff --git a/drivers/net/ethernet/sfc/ptp.c b/drivers/net/ethernet/sfc/ptp.c
index 5578c54..ad62615 100644
--- a/drivers/net/ethernet/sfc/ptp.c
+++ b/drivers/net/ethernet/sfc/ptp.c
@@ -306,7 +306,7 @@ struct efx_ptp_data {
 	struct work_struct pps_work;
 	struct workqueue_struct *pps_workwq;
 	bool nic_ts_enabled;
-	MCDI_DECLARE_BUF(txbuf, MC_CMD_PTP_IN_TRANSMIT_LENMAX);
+	_MCDI_DECLARE_BUF(txbuf, MC_CMD_PTP_IN_TRANSMIT_LENMAX);
 
 	unsigned int good_syncs;
 	unsigned int fast_syncs;
@@ -573,7 +573,7 @@ static int efx_ptp_get_timestamp_corrections(struct efx_nic *efx)
 static int efx_ptp_enable(struct efx_nic *efx)
 {
 	MCDI_DECLARE_BUF(inbuf, MC_CMD_PTP_IN_ENABLE_LEN);
-	MCDI_DECLARE_BUF_OUT_OR_ERR(outbuf, 0);
+	MCDI_DECLARE_BUF_ERR(outbuf);
 	int rc;
 
 	MCDI_SET_DWORD(inbuf, PTP_IN_OP, MC_CMD_PTP_OP_ENABLE);
@@ -601,7 +601,7 @@ static int efx_ptp_enable(struct efx_nic *efx)
 static int efx_ptp_disable(struct efx_nic *efx)
 {
 	MCDI_DECLARE_BUF(inbuf, MC_CMD_PTP_IN_DISABLE_LEN);
-	MCDI_DECLARE_BUF_OUT_OR_ERR(outbuf, 0);
+	MCDI_DECLARE_BUF_ERR(outbuf);
 	int rc;
 
 	MCDI_SET_DWORD(inbuf, PTP_IN_OP, MC_CMD_PTP_OP_DISABLE);

Re: [PATCH net-next 0/4] sfc: add MCDI tracing

[David Miller]

From: Edward Cree <ecree@solarflare.com>
Date: Tue, 19 May 2015 18:33:55 +0100

> This patchset adds support for logging Management-Controller-to-Driver Interface interactions between the sfc driver and a bound device, to aid in debugging.
> Solarflare has a tool to decode the resulting traces and will look to open-source this if there is any external interest, but the protocol is already detailed in drivers/net/ethernet/sfc/mcdi_pcol.h.

Please properly format your email message body contents to ~80
columns.

Thanks.