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Subject[PATCH v2] mmc: dw_mmc: Add data CRC error injection
Date
This driver has had problems when handling data errors.  Add fault
injection support so that the abort handling can be easily triggered and
regression-tested. A hrtimer is used to indicate a data CRC error at
various points during the data transfer.

Note that for the recent problem with hangs in the case of some data CRC
errors, a udelay(10) inserted at the start of send_stop_abort() greatly
helped in triggering the error, but I've not included this as part of
the fault injection support since it seemed too specific.

Signed-off-by: Vincent Whitchurch <vincent.whitchurch@axis.com>
---

Notes:
v2: Add missing includes.

drivers/mmc/host/dw_mmc.c | 73 +++++++++++++++++++++++++++++++++++++++
drivers/mmc/host/dw_mmc.h | 7 ++++
2 files changed, 80 insertions(+)

diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
index d333130d1531..dbbb94e6ff4b 100644
--- a/drivers/mmc/host/dw_mmc.c
+++ b/drivers/mmc/host/dw_mmc.c
@@ -17,9 +17,11 @@
#include <linux/interrupt.h>
#include <linux/iopoll.h>
#include <linux/ioport.h>
+#include <linux/ktime.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/pm_runtime.h>
+#include <linux/prandom.h>
#include <linux/seq_file.h>
#include <linux/slab.h>
#include <linux/stat.h>
@@ -181,6 +183,9 @@ static void dw_mci_init_debugfs(struct dw_mci_slot *slot)
&host->pending_events);
debugfs_create_xul("completed_events", S_IRUSR, root,
&host->completed_events);
+#ifdef CONFIG_FAULT_INJECTION
+ fault_create_debugfs_attr("fail_data_crc", root, &host->fail_data_crc);
+#endif
}
#endif /* defined(CONFIG_DEBUG_FS) */

@@ -1788,6 +1793,68 @@ static const struct mmc_host_ops dw_mci_ops = {
.prepare_hs400_tuning = dw_mci_prepare_hs400_tuning,
};

+#ifdef CONFIG_FAULT_INJECTION
+static enum hrtimer_restart dw_mci_fault_timer(struct hrtimer *t)
+{
+ struct dw_mci *host = container_of(t, struct dw_mci, fault_timer);
+ unsigned long flags;
+
+ spin_lock_irqsave(&host->irq_lock, flags);
+
+ if (!host->data_status)
+ host->data_status = SDMMC_INT_DCRC;
+ set_bit(EVENT_DATA_ERROR, &host->pending_events);
+ tasklet_schedule(&host->tasklet);
+
+ spin_unlock_irqrestore(&host->irq_lock, flags);
+
+ return HRTIMER_NORESTART;
+}
+
+static void dw_mci_start_fault_timer(struct dw_mci *host)
+{
+ struct mmc_data *data = host->data;
+
+ if (!data || data->blocks <= 1)
+ return;
+
+ if (!should_fail(&host->fail_data_crc, 1))
+ return;
+
+ /*
+ * Try to inject the error at random points during the data transfer.
+ */
+ hrtimer_start(&host->fault_timer,
+ ms_to_ktime(prandom_u32() % 25),
+ HRTIMER_MODE_REL);
+}
+
+static void dw_mci_stop_fault_timer(struct dw_mci *host)
+{
+ hrtimer_cancel(&host->fault_timer);
+}
+
+static void dw_mci_init_fault(struct dw_mci *host)
+{
+ host->fail_data_crc = (struct fault_attr) FAULT_ATTR_INITIALIZER;
+
+ hrtimer_init(&host->fault_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
+ host->fault_timer.function = dw_mci_fault_timer;
+}
+#else
+static void dw_mci_init_fault(struct dw_mci *host)
+{
+}
+
+static void dw_mci_start_fault_timer(struct dw_mci *host)
+{
+}
+
+static void dw_mci_stop_fault_timer(struct dw_mci *host)
+{
+}
+#endif
+
static void dw_mci_request_end(struct dw_mci *host, struct mmc_request *mrq)
__releases(&host->lock)
__acquires(&host->lock)
@@ -2102,6 +2169,7 @@ static void dw_mci_tasklet_func(struct tasklet_struct *t)
break;
}

+ dw_mci_stop_fault_timer(host);
host->data = NULL;
set_bit(EVENT_DATA_COMPLETE, &host->completed_events);
err = dw_mci_data_complete(host, data);
@@ -2151,6 +2219,7 @@ static void dw_mci_tasklet_func(struct tasklet_struct *t)
if (mrq->cmd->error && mrq->data)
dw_mci_reset(host);

+ dw_mci_stop_fault_timer(host);
host->cmd = NULL;
host->data = NULL;

@@ -2600,6 +2669,8 @@ static void dw_mci_cmd_interrupt(struct dw_mci *host, u32 status)

set_bit(EVENT_CMD_COMPLETE, &host->pending_events);
tasklet_schedule(&host->tasklet);
+
+ dw_mci_start_fault_timer(host);
}

static void dw_mci_handle_cd(struct dw_mci *host)
@@ -3223,6 +3294,8 @@ int dw_mci_probe(struct dw_mci *host)
spin_lock_init(&host->irq_lock);
INIT_LIST_HEAD(&host->queue);

+ dw_mci_init_fault(host);
+
/*
* Get the host data width - this assumes that HCON has been set with
* the correct values.
diff --git a/drivers/mmc/host/dw_mmc.h b/drivers/mmc/host/dw_mmc.h
index da5923a92e60..ce05d81477d9 100644
--- a/drivers/mmc/host/dw_mmc.h
+++ b/drivers/mmc/host/dw_mmc.h
@@ -14,6 +14,8 @@
#include <linux/mmc/core.h>
#include <linux/dmaengine.h>
#include <linux/reset.h>
+#include <linux/fault-inject.h>
+#include <linux/hrtimer.h>
#include <linux/interrupt.h>

enum dw_mci_state {
@@ -230,6 +232,11 @@ struct dw_mci {
struct timer_list cmd11_timer;
struct timer_list cto_timer;
struct timer_list dto_timer;
+
+#ifdef CONFIG_FAULT_INJECTION
+ struct fault_attr fail_data_crc;
+ struct hrtimer fault_timer;
+#endif
};

/* DMA ops for Internal/External DMAC interface */
--
2.28.0
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