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Merge tag 'mmc-v4.14-rc4-3' of git://git.kernel.org/pub/scm/linux/ker…
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…nel/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
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@torvalds
torvalds committed Nov 3, 2017
2 parents e65a139 + 9d9491a commit 3f46540
Showing 1 changed file with 94 additions and 13 deletions.
107 changes: 94 additions & 13 deletions drivers/mmc/host/dw_mmc.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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,
Expand All @@ -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)
Expand Down Expand Up @@ -1915,17 +1936,40 @@ 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;

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;
Expand All @@ -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;
Expand Down Expand Up @@ -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 */
Expand Down Expand Up @@ -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;

Expand All @@ -2594,15 +2638,14 @@ 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 */

if (pending) {
/* 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;

Expand All @@ -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) {
Expand Down Expand Up @@ -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) {
Expand Down Expand Up @@ -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:
Expand All @@ -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)
Expand Down

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