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Message-ID: <20210630102243.17096-1-vincent.whitchurch@axis.com>
Date: Wed, 30 Jun 2021 12:22:43 +0200
From: Vincent Whitchurch <vincent.whitchurch@...s.com>
To: Jaehoon Chung <jh80.chung@...sung.com>,
Ulf Hansson <ulf.hansson@...aro.org>
CC: <kernel@...s.com>,
Vincent Whitchurch <vincent.whitchurch@...s.com>,
<linux-mmc@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: [PATCH] mmc: dw_mmc: Add data CRC error injection
This driver has issues when handling data CRC errors. Add fault
injection support so that the handling can be easily triggered and
regression-tested. A hrtimer is used to indicate a data CRC errors 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@...s.com>
---
drivers/mmc/host/dw_mmc.c | 71 +++++++++++++++++++++++++++++++++++++++
drivers/mmc/host/dw_mmc.h | 5 +++
2 files changed, 76 insertions(+)
diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
index d333130d1531..f85271f5c4fa 100644
--- a/drivers/mmc/host/dw_mmc.c
+++ b/drivers/mmc/host/dw_mmc.c
@@ -181,6 +181,9 @@ 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 +1791,68 @@ 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 +2167,7 @@ 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 +2217,7 @@ 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 +2667,8 @@ 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 +3292,8 @@ 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..4eb9c5b6c017 100644
--- a/drivers/mmc/host/dw_mmc.h
+++ b/drivers/mmc/host/dw_mmc.h
@@ -230,6 +230,11 @@ 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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