mmc: dw_mmc: Add data CRC error injection

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>
Reviewed-by: Jaehoon Chung <jh80.chung@samsung.com>
Link: https://lore.kernel.org/r/20210701080534.23138-1-vincent.whitchurch@axis.com
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
index c3229d8..29c848e 100644 (file)
--- 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 da5923a..ce05d81 100644 (file)
--- 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 */