Commit 2b8ac062 authored by Vincent Whitchurch's avatar Vincent Whitchurch Committed by Ulf Hansson
Browse files

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: default avatarVincent Whitchurch <vincent.whitchurch@axis.com>
Reviewed-by: default avatarJaehoon Chung <jh80.chung@samsung.com>
Link: https://lore.kernel.org/r/20210701080534.23138-1-vincent.whitchurch@axis.com


Signed-off-by: default avatarUlf Hansson <ulf.hansson@linaro.org>
parent 69606847

drivers/mmc/host/dw_mmc.c

+73 −0
Original line number Diff line number Diff line
@@ -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.

drivers/mmc/host/dw_mmc.h

+7 −0
Original line number Diff line number Diff line
@@ -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 */