Re: [RFC,v2] Bluetooth: hci_qca: Collect controller memory dump during SSR

From: Balakrishna Godavarthi
Date: Fri Jan 04 2019 - 01:18:30 EST

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Hi Marcel,

On 2018-12-29 12:57, Marcel Holtmann wrote:

Hi Balakrishna,

We will collect the ramdump of BT controller when hardware error event
received before rebooting the HCI layer. Before restarting a subsystem
or a process running on a subsystem, it is often required to request
either a subsystem or a process to perform proper cache dump and
software failure reason into a memory buffer which application
processor can retrieve afterwards. SW developers can often provide
initial investigation by looking into that debugging information.

Signed-off-by: Balakrishna Godavarthi <bgodavar@xxxxxxxxxxxxxx>
---
changes v2:
* entirely an newer approach handling with an work queue.

---
drivers/bluetooth/hci_qca.c | 289 ++++++++++++++++++++++++++++++++++--
1 file changed, 278 insertions(+), 11 deletions(-)

diff --git a/drivers/bluetooth/hci_qca.c b/drivers/bluetooth/hci_qca.c
index f036c8f98ea3..62b768bc32ec 100644
--- a/drivers/bluetooth/hci_qca.c
+++ b/drivers/bluetooth/hci_qca.c
@@ -32,6 +32,7 @@
#include <linux/clk.h>
#include <linux/debugfs.h>
#include <linux/delay.h>
+#include <linux/devcoredump.h>
#include <linux/device.h>
#include <linux/gpio/consumer.h>
#include <linux/mod_devicetable.h>

don't we have some crashdump core facility that could be utilized here?

[Bala]: no i don't think so. that is reason calling devcoredump.h

@@ -57,9 +58,10 @@
/* Controller states */
#define STATE_IN_BAND_SLEEP_ENABLED 1

-#define IBS_WAKE_RETRANS_TIMEOUT_MS 100
+#define IBS_WAKE_RETRANS_TIMEOUT_MS 100
#define IBS_TX_IDLE_TIMEOUT_MS 2000
-#define BAUDRATE_SETTLE_TIMEOUT_MS 300
+#define BAUDRATE_SETTLE_TIMEOUT_MS 300
+#define MEMDUMP_COLLECTION_TIMEOUT_MS 8000

/* susclk rate */
#define SUSCLK_RATE_32KHZ 32768
@@ -67,6 +69,13 @@
/* Controller debug log header */
#define QCA_DEBUG_HANDLE 0x2EDC

+/* Controller dump header */
+#define QCA_SSR_DUMP_HANDLE 0x0108
+#define QCA_DUMP_PACKET_SIZE 255
+#define QCA_LAST_SEQUENCE_NUM 0xFFFF
+#define QCA_CRASHBYTE_PACKET_LEN 1100
+#define QCA_MEMDUMP_BYTE 0xFB
+
/* HCI_IBS transmit side sleep protocol states */
enum tx_ibs_states {
HCI_IBS_TX_ASLEEP,
@@ -89,12 +98,41 @@ enum hci_ibs_clock_state_vote {
HCI_IBS_RX_VOTE_CLOCK_OFF,
};

+/* Controller memory dump states */
+enum qca_memdump_states {
+ QCA_MEMDUMP_IDLE,
+ QCA_MEMDUMP_COLLECTING,
+ QCA_MEMDUMP_COLLECTED,
+ QCA_MEMDUMP_TIMEOUT,
+};
+
+struct qca_memdump_data {
+ char *memdump_buf_head;
+ char *memdump_buf_tail;
+ u32 current_seq_no;
+ u32 received_dump;
+};
+
+struct qca_memdump_event_hdr {
+ __u8 evt;
+ __u8 plen;
+ __u16 opcode;
+ __u16 seq_no;
+ __u8 reserved;
+} __packed;
+
+
+struct qca_dump_size {
+ u32 dump_size;
+} __packed;
+
struct qca_data {
struct hci_uart *hu;
struct sk_buff *rx_skb;
struct sk_buff_head txq;
- struct sk_buff_head tx_wait_q; /* HCI_IBS wait queue */
- spinlock_t hci_ibs_lock; /* HCI_IBS state lock */
+ struct sk_buff_head tx_wait_q; /* HCI_IBS wait queue */
+ struct sk_buff_head rx_memdump_q; /* Memdump wait queue */
+ spinlock_t hci_ibs_lock; /* HCI_IBS state lock */
u8 tx_ibs_state; /* HCI_IBS transmit side power state*/
u8 rx_ibs_state; /* HCI_IBS receive side power state */
bool tx_vote; /* Clock must be on for TX */
@@ -103,12 +141,17 @@ struct qca_data {
u32 tx_idle_delay;
struct timer_list wake_retrans_timer;
u32 wake_retrans;
+ struct timer_list memdump_timer;
+ u32 memdump_delay;
struct workqueue_struct *workqueue;
struct work_struct ws_awake_rx;
struct work_struct ws_awake_device;
struct work_struct ws_rx_vote_off;
struct work_struct ws_tx_vote_off;
+ struct work_struct ctrl_memdump_evt;
+ struct qca_memdump_data *qca_memdump;
unsigned long flags;
+ enum qca_memdump_states memdump_state;

/* For debugging purpose */
u64 ibs_sent_wacks;
@@ -173,6 +216,7 @@ struct qca_serdev {
static int qca_power_setup(struct hci_uart *hu, bool on);
static void qca_power_shutdown(struct hci_uart *hu);
static int qca_power_off(struct hci_dev *hdev);
+static void qca_controller_memdump(struct work_struct *work);

static void __serial_clock_on(struct tty_struct *tty)
{
@@ -446,6 +490,21 @@ static void hci_ibs_wake_retrans_timeout(struct timer_list *t)
hci_uart_tx_wakeup(hu);
}

+static void hci_memdump_timeout(struct timer_list *t)
+{
+ struct qca_data *qca = from_timer(qca, t, tx_idle_timer);
+ struct hci_uart *hu = qca->hu;
+ struct qca_memdump_data *qca_memdump = qca->qca_memdump;
+ char *memdump_buf = qca_memdump->memdump_buf_tail;
+
+ bt_dev_err(hu->hdev, "clearing allocated memory due to memdump timeout");
+ kfree(memdump_buf);
+ kfree(qca_memdump);
+ qca->memdump_state = QCA_MEMDUMP_TIMEOUT;
+ del_timer(&qca->memdump_timer);
+ cancel_work_sync(&qca->ctrl_memdump_evt);
+}
+
/* Initialize protocol */
static int qca_open(struct hci_uart *hu)
{
@@ -461,6 +520,7 @@ static int qca_open(struct hci_uart *hu)

skb_queue_head_init(&qca->txq);
skb_queue_head_init(&qca->tx_wait_q);
+ skb_queue_head_init(&qca->rx_memdump_q);
spin_lock_init(&qca->hci_ibs_lock);
qca->workqueue = alloc_ordered_workqueue("qca_wq", 0);
if (!qca->workqueue) {
@@ -473,6 +533,7 @@ static int qca_open(struct hci_uart *hu)
INIT_WORK(&qca->ws_awake_device, qca_wq_awake_device);
INIT_WORK(&qca->ws_rx_vote_off, qca_wq_serial_rx_clock_vote_off);
INIT_WORK(&qca->ws_tx_vote_off, qca_wq_serial_tx_clock_vote_off);
+ INIT_WORK(&qca->ctrl_memdump_evt, qca_controller_memdump);

qca->hu = hu;

@@ -500,7 +561,7 @@ static int qca_open(struct hci_uart *hu)
qca->tx_votes_off = 0;
qca->rx_votes_on = 0;
qca->rx_votes_off = 0;
-
+ qca->memdump_state = QCA_MEMDUMP_IDLE;
hu->priv = qca;

if (hu->serdev) {
@@ -528,6 +589,9 @@ static int qca_open(struct hci_uart *hu)
timer_setup(&qca->tx_idle_timer, hci_ibs_tx_idle_timeout, 0);
qca->tx_idle_delay = IBS_TX_IDLE_TIMEOUT_MS;

+ timer_setup(&qca->memdump_timer, hci_memdump_timeout, 0);
+ qca->memdump_delay = MEMDUMP_COLLECTION_TIMEOUT_MS;
+
BT_DBG("HCI_UART_QCA open, tx_idle_delay=%u, wake_retrans=%u",
qca->tx_idle_delay, qca->wake_retrans);

@@ -605,8 +669,10 @@ static int qca_close(struct hci_uart *hu)

skb_queue_purge(&qca->tx_wait_q);
skb_queue_purge(&qca->txq);
+ skb_queue_purge(&qca->rx_memdump_q);
del_timer(&qca->tx_idle_timer);
del_timer(&qca->wake_retrans_timer);
+ del_timer(&qca->memdump_timer);
destroy_workqueue(qca->workqueue);
qca->hu = NULL;

@@ -866,6 +932,141 @@ static int qca_recv_acl_data(struct hci_dev *hdev, struct sk_buff *skb)
return hci_recv_frame(hdev, skb);
}

+static void qca_controller_memdump(struct work_struct *work)
+{
+ struct qca_data *qca = container_of(work, struct qca_data,
+ ctrl_memdump_evt);
+ struct hci_uart *hu = qca->hu;
+ struct sk_buff *skb;
+ struct qca_memdump_event_hdr *cmd_hdr;
+ struct qca_memdump_data *qca_memdump = qca->qca_memdump;
+ struct qca_dump_size *dump;
+ char *memdump_buf;
+ char nullBuff[QCA_DUMP_PACKET_SIZE] = { 0 };
+ u16 opcode, seq_no;
+ u32 dump_size;
+
+ while ((skb = skb_dequeue(&qca->rx_memdump_q))) {
+
+ if (!qca_memdump) {
+ qca_memdump = kzalloc(sizeof(struct qca_memdump_data),
+ GFP_ATOMIC);
+ if (!qca_memdump)
+ return;
+
+ qca->qca_memdump = qca_memdump;
+ }
+
+ qca->memdump_state = QCA_MEMDUMP_COLLECTING;
+ cmd_hdr = (void *) skb->data;
+ opcode = __le16_to_cpu(cmd_hdr->opcode);
+ seq_no = __le16_to_cpu(cmd_hdr->seq_no);
+ skb_pull(skb, sizeof(struct qca_memdump_event_hdr));
+
+ if (!seq_no) {
+
+ /* This is the first frame of memdump packet from
+ * the controller, Disable IBS to recevie dump
+ * with out any interruption, ideally time required for
+ * the controller to send the dump is 8 seconds. let us
+ * start timer to handle this asynchronous activity.
+ */
+ clear_bit(STATE_IN_BAND_SLEEP_ENABLED, &qca->flags);
+
+ dump = (void *) skb->data;
+ dump_size = __le32_to_cpu(dump->dump_size);
+ if (!(dump_size)) {
+ bt_dev_err(hu->hdev, "QCA invalid memdump size");
+ kfree_skb(skb);
+ return;
+ }
+
+ bt_dev_info(hu->hdev, "QCA: collecting memdump started"
+ "of size:%u", dump_size);
+ mod_timer(&qca->memdump_timer, (jiffies +
+ msecs_to_jiffies(qca->memdump_delay)));
+
+ skb_pull(skb, sizeof(dump_size));
+ memdump_buf = vmalloc(dump_size);
+ qca_memdump->memdump_buf_head = memdump_buf;
+ qca_memdump->memdump_buf_tail = memdump_buf;
+ }
+
+ memdump_buf = qca_memdump->memdump_buf_tail;
+
+ /* If sequence no 0 is missed then there is no point in
+ * accepting the other sequences.
+ */
+ if (!memdump_buf) {
+ bt_dev_err(hu->hdev, "QCA: Discarding other packets");
+ kfree(qca_memdump);
+ kfree_skb(skb);
+ qca->qca_memdump = NULL;
+ return;
+ }
+
+ /* There could be chance of missing some packets from
+ * the controller. In such cases let us store the dummy
+ * packets in the buffer.
+ */
+ while ((seq_no > qca_memdump->current_seq_no + 1) &&
+ seq_no != QCA_LAST_SEQUENCE_NUM) {
+ bt_dev_err(hu->hdev, "QCA controller missed packet:%d",
+ qca_memdump->current_seq_no);
+ memcpy(memdump_buf, nullBuff, QCA_DUMP_PACKET_SIZE);
+ memdump_buf = memdump_buf + QCA_DUMP_PACKET_SIZE;
+ qca_memdump->received_dump += QCA_DUMP_PACKET_SIZE;
+ qca_memdump->current_seq_no++;
+ }
+
+ memcpy(memdump_buf, (unsigned char *) skb->data, skb->len);
+ memdump_buf = memdump_buf + skb->len;
+ qca_memdump->memdump_buf_tail = memdump_buf;
+ qca_memdump->current_seq_no = seq_no + 1;
+ qca_memdump->received_dump += skb->len;
+ qca->qca_memdump = qca_memdump;
+ kfree_skb(skb);
+ if (seq_no == QCA_LAST_SEQUENCE_NUM) {
+ bt_dev_info(hu->hdev, "QCA writing crash dump of size %d bytes",
+ qca_memdump->received_dump);
+ memdump_buf = qca_memdump->memdump_buf_head;
+ dev_coredumpv(&hu->serdev->dev, memdump_buf,
+ qca_memdump->received_dump, GFP_KERNEL);
+ // Revisit for free(memdump) if needed.
+ del_timer(&qca->memdump_timer);
+ kfree(qca->qca_memdump);
+ qca->qca_memdump = NULL;
+ qca->memdump_state = QCA_MEMDUMP_COLLECTED;
+ }
+ }
+
+}
+
+int qca_controller_memdump_event(struct hci_dev *hdev, struct sk_buff *skb)
+{
+ struct hci_uart *hu = hci_get_drvdata(hdev);
+ struct qca_data *qca = hu->priv;
+
+ skb_queue_tail(&qca->rx_memdump_q, skb);
+ queue_work(qca->workqueue, &qca->ctrl_memdump_evt);
+
+ return 0;
+}
+
+static int qca_recv_event_data(struct hci_dev *hdev, struct sk_buff *skb)
+{
+ /* We receive chip memory dump as an event packet, With a dedicated
+ * handler followed by a hardware error event. When this event is
+ * received we store dump into a file before closing hci. This
+ * dump will help in triaging the issues.
+ */
+ if ((skb->data[0] == HCI_VENDOR_PKT) &&
+ (get_unaligned_be16((skb->data) + 2) == QCA_SSR_DUMP_HANDLE))

The (skb->data) is pointless, just do skb->data.

[Bala]: will update.

+ return qca_controller_memdump_event(hdev, skb);
+
+ return hci_recv_frame(hdev, skb);
+}
+
#define QCA_IBS_SLEEP_IND_EVENT \
.type = HCI_IBS_SLEEP_IND, \
.hlen = 0, \
@@ -888,12 +1089,12 @@ static int qca_recv_acl_data(struct hci_dev *hdev, struct sk_buff *skb)
.maxlen = HCI_MAX_IBS_SIZE

static const struct h4_recv_pkt qca_recv_pkts[] = {
- { H4_RECV_ACL, .recv = qca_recv_acl_data },
- { H4_RECV_SCO, .recv = hci_recv_frame },
- { H4_RECV_EVENT, .recv = hci_recv_frame },
- { QCA_IBS_WAKE_IND_EVENT, .recv = qca_ibs_wake_ind },
- { QCA_IBS_WAKE_ACK_EVENT, .recv = qca_ibs_wake_ack },
- { QCA_IBS_SLEEP_IND_EVENT, .recv = qca_ibs_sleep_ind },
+ { H4_RECV_ACL, .recv = qca_recv_acl_data },
+ { H4_RECV_SCO, .recv = hci_recv_frame },
+ { H4_RECV_EVENT, .recv = qca_recv_event_data },

call it qca_recv_event and don't realign the whole table.

[Bala]: will update.

+ { QCA_IBS_WAKE_IND_EVENT, .recv = qca_ibs_wake_ind },
+ { QCA_IBS_WAKE_ACK_EVENT, .recv = qca_ibs_wake_ack },
+ { QCA_IBS_SLEEP_IND_EVENT, .recv = qca_ibs_sleep_ind },
};

static int qca_recv(struct hci_uart *hu, const void *data, int count)
@@ -1114,6 +1315,68 @@ static int qca_set_speed(struct hci_uart *hu, enum qca_speed_type speed_type)
return 0;
}

+static int qca_send_crashbuffer(struct hci_uart *hu)
+{
+ struct qca_data *qca = hu->priv;
+ struct sk_buff *skb;
+ unsigned char buf[QCA_CRASHBYTE_PACKET_LEN];
+
+ bt_dev_dbg(hu->hdev, "sending soc crash buffer to controller");
+
+ /* We forcefully crash the controller, by sending 0xfb byte for
+ * 1024 times. We also might have chance of losing data, To be
+ * on safer side we send 1100 bytes to the SoC.
+ */
+ memset(buf, QCA_MEMDUMP_BYTE, QCA_CRASHBYTE_PACKET_LEN);
+
+ skb = bt_skb_alloc(QCA_CRASHBYTE_PACKET_LEN, GFP_KERNEL);
+ if (!skb) {
+ bt_dev_err(hu->hdev, "Failed to allocate memory for skb packet");
+ return -ENOMEM;
+ }
+
+ skb_put_data(skb, buf, QCA_CRASHBYTE_PACKET_LEN);
+ hci_skb_pkt_type(skb) = HCI_COMMAND_PKT;
+
+ skb_queue_tail(&qca->txq, skb);
+ hci_uart_tx_wakeup(hu);
+
+ return 0;
+}
+
+static void qca_hw_error(struct hci_dev *hdev, u8 code)
+{
+ struct hci_uart *hu = hci_get_drvdata(hdev);
+ struct qca_data *qca = hu->priv;
+
+ bt_dev_info(hdev, "mem_dump_status: %d", qca->memdump_state);
+
+ if (qca->memdump_state == QCA_MEMDUMP_IDLE) {
+ /* If hardware error event received for other than QCA
+ * soc memory dump event, then we need to crash the SOC
+ * and wait here for 8 seconds to get the dump packets.
+ * This will block main thread to be on hold until we
+ * collect dump.
+ */
+ mod_timer(&qca->memdump_timer,
+ (jiffies + msecs_to_jiffies(qca->memdump_delay)));

Why a timer that then ends up in interrupt context?

[Bala]: some times we only receive hardware error from the chip, so we are sending an special buffer to request the
chip for memory dump. we are using an timer to check whether the data memdump is collected. if the timer
over flows we are cleaning up all the assigned memory and unblock the main thread,
in short this timer is a watch dog timer for the memory dump collection.

+ qca_send_crashbuffer(hu);
+
+ while (qca->memdump_state != QCA_MEMDUMP_COLLECTED &&
+ qca->memdump_state != QCA_MEMDUMP_TIMEOUT)
+ ;

What is this? Busy loop? I rather not do that.

[Bala]: this busy required to collected the dump from the chip before we close an reopen the hci.
>> + } else if (qca->memdump_state == QCA_MEMDUMP_COLLECTING) {

+ /* Let us wait here until memory dump collected or
+ * memory dump timer expired.
+ */
+ bt_dev_info(hdev, "waiting for dump to complete");
+ while (qca->memdump_state == QCA_MEMDUMP_COLLECTING)
+ ;
+ }
+
+ qca->memdump_state = QCA_MEMDUMP_IDLE;
+}
+
static int qca_wcn3990_init(struct hci_uart *hu)
{
struct hci_dev *hdev = hu->hdev;
@@ -1229,6 +1492,10 @@ static int qca_setup(struct hci_uart *hu)
if (!ret) {
set_bit(STATE_IN_BAND_SLEEP_ENABLED, &qca->flags);
qca_debugfs_init(hdev);
+ /* We only get controller dump when fw download is
+ * successful.
+ */
+ hu->hdev->hw_error = qca_hw_error;

I would set this all the time and handle it with a flag if firmware
downloaded has succeeded or not.

[Bala]: ok will update.

} else if (ret == -ENOENT) {
/* No patch/nvm-config found, run with original fw/config */
ret = 0;

Regards

Marcel

--
Regards
Balakrishna.

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