Merge tag 'mmc-v4.14-rc4-3' of git://git.kernel.org/pub/scm/linux/kernel/git/ulfh/mmc
Pull MMC fixes from Ulf Hansson:
"Fix dw_mmc request timeout issues"
* tag 'mmc-v4.14-rc4-3' of git://git.kernel.org/pub/scm/linux/kernel/git/ulfh/mmc:
mmc: dw_mmc: Fix the DTO timeout calculation
mmc: dw_mmc: Add locking to the CTO timer
mmc: dw_mmc: Fix the CTO timeout calculation
mmc: dw_mmc: cancel the CTO timer after a voltage switch
diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
index 860313b..4f28067 100644
--- a/drivers/mmc/host/dw_mmc.c
+++ b/drivers/mmc/host/dw_mmc.c
@@ -401,16 +401,37 @@ static u32 dw_mci_prep_stop_abort(struct dw_mci *host, struct mmc_command *cmd)
static inline void dw_mci_set_cto(struct dw_mci *host)
{
unsigned int cto_clks;
+ unsigned int cto_div;
unsigned int cto_ms;
+ unsigned long irqflags;
cto_clks = mci_readl(host, TMOUT) & 0xff;
- cto_ms = DIV_ROUND_UP(cto_clks, host->bus_hz / 1000);
+ cto_div = (mci_readl(host, CLKDIV) & 0xff) * 2;
+ if (cto_div == 0)
+ cto_div = 1;
+ cto_ms = DIV_ROUND_UP(MSEC_PER_SEC * cto_clks * cto_div, host->bus_hz);
/* add a bit spare time */
cto_ms += 10;
- mod_timer(&host->cto_timer,
- jiffies + msecs_to_jiffies(cto_ms) + 1);
+ /*
+ * The durations we're working with are fairly short so we have to be
+ * extra careful about synchronization here. Specifically in hardware a
+ * command timeout is _at most_ 5.1 ms, so that means we expect an
+ * interrupt (either command done or timeout) to come rather quickly
+ * after the mci_writel. ...but just in case we have a long interrupt
+ * latency let's add a bit of paranoia.
+ *
+ * In general we'll assume that at least an interrupt will be asserted
+ * in hardware by the time the cto_timer runs. ...and if it hasn't
+ * been asserted in hardware by that time then we'll assume it'll never
+ * come.
+ */
+ spin_lock_irqsave(&host->irq_lock, irqflags);
+ if (!test_bit(EVENT_CMD_COMPLETE, &host->pending_events))
+ mod_timer(&host->cto_timer,
+ jiffies + msecs_to_jiffies(cto_ms) + 1);
+ spin_unlock_irqrestore(&host->irq_lock, irqflags);
}
static void dw_mci_start_command(struct dw_mci *host,
@@ -425,11 +446,11 @@ static void dw_mci_start_command(struct dw_mci *host,
wmb(); /* drain writebuffer */
dw_mci_wait_while_busy(host, cmd_flags);
+ mci_writel(host, CMD, cmd_flags | SDMMC_CMD_START);
+
/* response expected command only */
if (cmd_flags & SDMMC_CMD_RESP_EXP)
dw_mci_set_cto(host);
-
- mci_writel(host, CMD, cmd_flags | SDMMC_CMD_START);
}
static inline void send_stop_abort(struct dw_mci *host, struct mmc_data *data)
@@ -1915,10 +1936,15 @@ static int dw_mci_data_complete(struct dw_mci *host, struct mmc_data *data)
static void dw_mci_set_drto(struct dw_mci *host)
{
unsigned int drto_clks;
+ unsigned int drto_div;
unsigned int drto_ms;
drto_clks = mci_readl(host, TMOUT) >> 8;
- drto_ms = DIV_ROUND_UP(drto_clks, host->bus_hz / 1000);
+ drto_div = (mci_readl(host, CLKDIV) & 0xff) * 2;
+ if (drto_div == 0)
+ drto_div = 1;
+ drto_ms = DIV_ROUND_UP(MSEC_PER_SEC * drto_clks * drto_div,
+ host->bus_hz);
/* add a bit spare time */
drto_ms += 10;
@@ -1926,6 +1952,24 @@ static void dw_mci_set_drto(struct dw_mci *host)
mod_timer(&host->dto_timer, jiffies + msecs_to_jiffies(drto_ms));
}
+static bool dw_mci_clear_pending_cmd_complete(struct dw_mci *host)
+{
+ if (!test_bit(EVENT_CMD_COMPLETE, &host->pending_events))
+ return false;
+
+ /*
+ * Really be certain that the timer has stopped. This is a bit of
+ * paranoia and could only really happen if we had really bad
+ * interrupt latency and the interrupt routine and timeout were
+ * running concurrently so that the del_timer() in the interrupt
+ * handler couldn't run.
+ */
+ WARN_ON(del_timer_sync(&host->cto_timer));
+ clear_bit(EVENT_CMD_COMPLETE, &host->pending_events);
+
+ return true;
+}
+
static void dw_mci_tasklet_func(unsigned long priv)
{
struct dw_mci *host = (struct dw_mci *)priv;
@@ -1952,8 +1996,7 @@ static void dw_mci_tasklet_func(unsigned long priv)
case STATE_SENDING_CMD11:
case STATE_SENDING_CMD:
- if (!test_and_clear_bit(EVENT_CMD_COMPLETE,
- &host->pending_events))
+ if (!dw_mci_clear_pending_cmd_complete(host))
break;
cmd = host->cmd;
@@ -2122,8 +2165,7 @@ static void dw_mci_tasklet_func(unsigned long priv)
/* fall through */
case STATE_SENDING_STOP:
- if (!test_and_clear_bit(EVENT_CMD_COMPLETE,
- &host->pending_events))
+ if (!dw_mci_clear_pending_cmd_complete(host))
break;
/* CMD error in data command */
@@ -2570,6 +2612,8 @@ static void dw_mci_write_data_pio(struct dw_mci *host)
static void dw_mci_cmd_interrupt(struct dw_mci *host, u32 status)
{
+ del_timer(&host->cto_timer);
+
if (!host->cmd_status)
host->cmd_status = status;
@@ -2594,6 +2638,7 @@ static irqreturn_t dw_mci_interrupt(int irq, void *dev_id)
struct dw_mci *host = dev_id;
u32 pending;
struct dw_mci_slot *slot = host->slot;
+ unsigned long irqflags;
pending = mci_readl(host, MINTSTS); /* read-only mask reg */
@@ -2601,8 +2646,6 @@ static irqreturn_t dw_mci_interrupt(int irq, void *dev_id)
/* Check volt switch first, since it can look like an error */
if ((host->state == STATE_SENDING_CMD11) &&
(pending & SDMMC_INT_VOLT_SWITCH)) {
- unsigned long irqflags;
-
mci_writel(host, RINTSTS, SDMMC_INT_VOLT_SWITCH);
pending &= ~SDMMC_INT_VOLT_SWITCH;
@@ -2618,11 +2661,15 @@ static irqreturn_t dw_mci_interrupt(int irq, void *dev_id)
}
if (pending & DW_MCI_CMD_ERROR_FLAGS) {
+ spin_lock_irqsave(&host->irq_lock, irqflags);
+
del_timer(&host->cto_timer);
mci_writel(host, RINTSTS, DW_MCI_CMD_ERROR_FLAGS);
host->cmd_status = pending;
smp_wmb(); /* drain writebuffer */
set_bit(EVENT_CMD_COMPLETE, &host->pending_events);
+
+ spin_unlock_irqrestore(&host->irq_lock, irqflags);
}
if (pending & DW_MCI_DATA_ERROR_FLAGS) {
@@ -2662,9 +2709,12 @@ static irqreturn_t dw_mci_interrupt(int irq, void *dev_id)
}
if (pending & SDMMC_INT_CMD_DONE) {
- del_timer(&host->cto_timer);
+ spin_lock_irqsave(&host->irq_lock, irqflags);
+
mci_writel(host, RINTSTS, SDMMC_INT_CMD_DONE);
dw_mci_cmd_interrupt(host, pending);
+
+ spin_unlock_irqrestore(&host->irq_lock, irqflags);
}
if (pending & SDMMC_INT_CD) {
@@ -2938,7 +2988,35 @@ static void dw_mci_cmd11_timer(unsigned long arg)
static void dw_mci_cto_timer(unsigned long arg)
{
struct dw_mci *host = (struct dw_mci *)arg;
+ unsigned long irqflags;
+ u32 pending;
+ spin_lock_irqsave(&host->irq_lock, irqflags);
+
+ /*
+ * If somehow we have very bad interrupt latency it's remotely possible
+ * that the timer could fire while the interrupt is still pending or
+ * while the interrupt is midway through running. Let's be paranoid
+ * and detect those two cases. Note that this is paranoia is somewhat
+ * justified because in this function we don't actually cancel the
+ * pending command in the controller--we just assume it will never come.
+ */
+ pending = mci_readl(host, MINTSTS); /* read-only mask reg */
+ if (pending & (DW_MCI_CMD_ERROR_FLAGS | SDMMC_INT_CMD_DONE)) {
+ /* The interrupt should fire; no need to act but we can warn */
+ dev_warn(host->dev, "Unexpected interrupt latency\n");
+ goto exit;
+ }
+ if (test_bit(EVENT_CMD_COMPLETE, &host->pending_events)) {
+ /* Presumably interrupt handler couldn't delete the timer */
+ dev_warn(host->dev, "CTO timeout when already completed\n");
+ goto exit;
+ }
+
+ /*
+ * Continued paranoia to make sure we're in the state we expect.
+ * This paranoia isn't really justified but it seems good to be safe.
+ */
switch (host->state) {
case STATE_SENDING_CMD11:
case STATE_SENDING_CMD:
@@ -2957,6 +3035,9 @@ static void dw_mci_cto_timer(unsigned long arg)
host->state);
break;
}
+
+exit:
+ spin_unlock_irqrestore(&host->irq_lock, irqflags);
}
static void dw_mci_dto_timer(unsigned long arg)
