[PATCH 1/2 v2] mmc: tmio: handle missing HW interrupts

Arnd Hannemann
2010-12-29T13:21:13Z

When doing excessive hotplug, e.g., repeated insert/eject operations,
the hardware may get confused to a point where no CMDTIMEOUT/CMDRESPEND
interrupts are generated any more.
As a result requests get stuck, e.g.:

[ 360.351562] INFO: task kworker/u:0:5 blocked for more than 120 seconds.
[ 360.351562] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[ 360.359375] kworker/u:0 D c020c2b4 0 5 2 0x00000000
[ 360.367187] Backtrace:
[ 360.367187] [<c020bfb0>] (schedule+0x0/0x340) from [<c020c480>] (schedule_timeout+0x20/0x190)
[ 360.375000] r8:c702fd70 r7:00000002 r6:c702e000 r5:c702fdc4 r4:7fffffff
[ 360.375000] r3:c701e040
[ 360.382812] [<c020c460>] (schedule_timeout+0x0/0x190) from [<c020be78>] (wait_for_common+0xc4/0x150)
[ 360.390625] r6:c702e000 r5:c702fdc4 r4:7fffffff
[ 360.390625] [<c020bdb4>] (wait_for_common+0x0/0x150) from [<c020bfac>] (wait_for_completion+0x18/0x1c)
[ 360.398437] [<c020bf94>] (wait_for_completion+0x0/0x1c) from [<c0185590>] (mmc_wait_for_req+0x214/0x234)
[ 360.406250] [<c018537c>] (mmc_wait_for_req+0x0/0x234) from [<c01889d0>] (mmc_sd_switch+0xfc/0x114)
[ 360.414062] r7:c702fe4c r6:c702fe20 r5:c7179800 r4:00fffff0
[ 360.421875] [<c01888d4>] (mmc_sd_switch+0x0/0x114) from [<c0187f70>] (mmc_sd_setup_card+0x260/0x384)
[ 360.429687] [<c0187d10>] (mmc_sd_setup_card+0x0/0x384) from [<c01885e0>] (mmc_sd_init_card+0x13c/0x1e0)
[ 360.437500] [<c01884a4>] (mmc_sd_init_card+0x0/0x1e0) from [<c01887a8>] (mmc_attach_sd+0x124/0x1a8)
[ 360.445312] r8:c02db404 r7:ffffff92 r6:c702ff34 r5:c6007da8 r4:c6007c00
[ 360.453125] [<c0188684>] (mmc_attach_sd+0x0/0x1a8) from [<c0185140>] (mmc_rescan+0x248/0x2f0)
[ 360.460937] r5:c6007da8 r4:c6007c00
[ 360.468750] [<c0184ef8>] (mmc_rescan+0x0/0x2f0) from [<c00467f0>] (process_one_work+0x1ec/0x318)
[ 360.476562] r7:c6007da8 r6:00000000 r5:c710ec00 r4:c701bde0
[ 360.484375] [<c0046604>] (process_one_work+0x0/0x318) from [<c0047fb0>] (worker_thread+0x1b0/0x2cc)
[ 360.492187] [<c0047e00>] (worker_thread+0x0/0x2cc) from [<c004b338>] (kthread+0x8c/0x94)
[ 360.500000] [<c004b2ac>] (kthread+0x0/0x94) from [<c0037fc4>] (do_exit+0x0/0x590)
[ 360.507812] r7:00000013 r6:c0037fc4 r5:c004b2ac r4:c7021f00

This patch addresses this problem by introducing timeouts for outstanding
interrupts. If a hardware interrupt is missing, a soft reset will be performed
to bring the hardware back to a working state.
Tested with the SDHI hardware block in sh7372 / AP4EVB.

Signed-off-by: Arnd Hannemann <arnd@arndnet.de>
---
Changes in v2:
- rebased against -rc7
- depends on:
mmc: tmio: merge the private header into the driver
https://patchwork.kernel.org/patch/349931/

drivers/mmc/host/tmio_mmc.c | 90 +++++++++++++++++++++++++++++++++++++++++--
1 files changed, 86 insertions(+), 4 deletions(-)

diff --git a/drivers/mmc/host/tmio_mmc.c b/drivers/mmc/host/tmio_mmc.c
index a0cf04a..f980042 100644
--- a/drivers/mmc/host/tmio_mmc.c
+++ b/drivers/mmc/host/tmio_mmc.c
@@ -39,6 +39,8 @@
#include <linux/module.h>
#include <linux/pagemap.h>
#include <linux/scatterlist.h>
+#include <linux/workqueue.h>
+#include <linux/spinlock.h>

#define CTL_SD_CMD 0x00
#define CTL_ARG_REG 0x04
@@ -154,6 +156,11 @@ struct tmio_mmc_host {
u8 bounce_buf[PAGE_CACHE_SIZE] __attribute__((aligned(MAX_ALIGN)));
struct scatterlist bounce_sg;
#endif
+
+ /* Track lost interrupts */
+ struct delayed_work delayed_reset_work;
+ spinlock_t lock;
+ unsigned long last_req_ts;
};

static u16 sd_ctrl_read16(struct tmio_mmc_host *host, int addr)
@@ -342,15 +349,60 @@ static void reset(struct tmio_mmc_host *host)
msleep(10);
}

+static void tmio_mmc_reset_work(struct work_struct *work)
+{
+ struct tmio_mmc_host *host = container_of(work, struct tmio_mmc_host,
+ delayed_reset_work.work);
+ struct mmc_request *mrq;
+ unsigned long flags;
+
+ spin_lock_irqsave(&host->lock, flags);
+ mrq = host->mrq;
+
+ /* request already finished */
+ if (!mrq
+ || time_is_after_jiffies(host->last_req_ts +
+ msecs_to_jiffies(2000))) {
+ spin_unlock_irqrestore(&host->lock, flags);
+ return;
+ }
+
+ dev_warn(&host->pdev->dev,
+ "timeout waiting for hardware interrupt (CMD%u)\n",
+ mrq->cmd->opcode);
+
+ if (host->data)
+ host->data->error = -ETIMEDOUT;
+ else if (host->cmd)
+ host->cmd->error = -ETIMEDOUT;
+ else
+ mrq->cmd->error = -ETIMEDOUT;
+
+ host->cmd = NULL;
+ host->data = NULL;
+ host->mrq = NULL;
+
+ spin_unlock_irqrestore(&host->lock, flags);
+
+ reset(host);
+
+ mmc_request_done(host->mmc, mrq);
+}
+
static void
tmio_mmc_finish_request(struct tmio_mmc_host *host)
{
struct mmc_request *mrq = host->mrq;

+ if (!mrq)
+ return;
+
host->mrq = NULL;
host->cmd = NULL;
host->data = NULL;

+ cancel_delayed_work(&host->delayed_reset_work);
+
mmc_request_done(host->mmc, mrq);
}

@@ -460,6 +512,7 @@ static void tmio_mmc_pio_irq(struct tmio_mmc_host *host)
return;
}

+/* needs to be called with host->lock held */
static void tmio_mmc_do_data_irq(struct tmio_mmc_host *host)
{
struct mmc_data *data = host->data;
@@ -520,10 +573,12 @@ static void tmio_mmc_do_data_irq(struct tmio_mmc_host *host)

static void tmio_mmc_data_irq(struct tmio_mmc_host *host)
{
- struct mmc_data *data = host->data;
+ struct mmc_data *data;
+ spin_lock(&host->lock);
+ data = host->data;

if (!data)
- return;
+ goto out;

if (host->chan_tx && (data->flags & MMC_DATA_WRITE)) {
/*
@@ -544,6 +599,8 @@ static void tmio_mmc_data_irq(struct tmio_mmc_host *host)
} else {
tmio_mmc_do_data_irq(host);
}
+out:
+ spin_unlock(&host->lock);
}

static void tmio_mmc_cmd_irq(struct tmio_mmc_host *host,
@@ -552,9 +609,11 @@ static void tmio_mmc_cmd_irq(struct tmio_mmc_host *host,
struct mmc_command *cmd = host->cmd;
int i, addr;

+ spin_lock(&host->lock);
+
if (!host->cmd) {
pr_debug("Spurious CMD irq\n");
- return;
+ goto out;
}

host->cmd = NULL;
@@ -599,6 +658,9 @@ static void tmio_mmc_cmd_irq(struct tmio_mmc_host *host,
tmio_mmc_finish_request(host);
}

+out:
+ spin_unlock(&host->lock);
+
return;
}

@@ -899,6 +961,12 @@ static void tmio_issue_tasklet_fn(unsigned long priv)
static void tmio_tasklet_fn(unsigned long arg)
{
struct tmio_mmc_host *host = (struct tmio_mmc_host *)arg;
+ unsigned long flags;
+
+ spin_lock_irqsave(&host->lock, flags);
+
+ if (!host->data)
+ goto out;

if (host->data->flags & MMC_DATA_READ)
dma_unmap_sg(&host->pdev->dev, host->sg_ptr, host->dma_sglen,
@@ -908,6 +976,8 @@ static void tmio_tasklet_fn(unsigned long arg)
DMA_TO_DEVICE);

tmio_mmc_do_data_irq(host);
+out:
+ spin_unlock_irqrestore(&host->lock, flags);
}

/* It might be necessary to make filter MFD specific */
@@ -1026,6 +1096,8 @@ static void tmio_mmc_request(struct mmc_host *mmc, struct mmc_request *mrq)
if (host->mrq)
pr_debug("request not null\n");

+ host->last_req_ts = jiffies;
+ wmb();
host->mrq = mrq;

if (mrq->data) {
@@ -1035,10 +1107,14 @@ static void tmio_mmc_request(struct mmc_host *mmc, struct mmc_request *mrq)
}

ret = tmio_mmc_start_command(host, mrq->cmd);
- if (!ret)
+ if (!ret) {
+ schedule_delayed_work(&host->delayed_reset_work,
+ msecs_to_jiffies(2000));
return;
+ }

fail:
+ host->mrq = NULL;
mrq->cmd->error = ret;
mmc_request_done(mmc, mrq);
}
@@ -1235,6 +1311,11 @@ static int __devinit tmio_mmc_probe(struct platform_device *dev)
if (ret)
goto cell_disable;

+ spin_lock_init(&host->lock);
+
+ /* Init delayed work for request timeouts */
+ INIT_DELAYED_WORK(&host->delayed_reset_work, tmio_mmc_reset_work);
+
/* See if we also get DMA */
tmio_mmc_request_dma(host, pdata);

@@ -1273,6 +1354,7 @@ static int __devexit tmio_mmc_remove(struct platform_device *dev)
if (mmc) {
struct tmio_mmc_host *host = mmc_priv(mmc);
mmc_remove_host(mmc);
+ cancel_delayed_work_sync(&host->delayed_reset_work);
tmio_mmc_release_dma(host);
free_irq(host->irq, host);
if (cell->disable)
--
1.7.2.3