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V4L/DVB (9595): cx18: Improve handling of outgoing mailboxes detected…
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… to be busy

cx18: Improve handling of outgoing mailboxes detected to be busy.  When
encountering a busy mailbox, sleep instead of polling, and wait for interrupt or
timeout.  If the mailbox is still busy, force it free.  When sending commands,
make sure we never create a situation where we mark the mailbox busy upon
sending, and ensure we always have a method to cleanly recover from a busy
mailbox.

Signed-off-by: Andy Walls <awalls@radix.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
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Andy Walls authored and Mauro Carvalho Chehab committed Dec 30, 2008
1 parent d670b6f commit ac50441
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Showing 2 changed files with 64 additions and 69 deletions.
3 changes: 2 additions & 1 deletion drivers/media/video/cx18/cx18-irq.c
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Original file line number Diff line number Diff line change
Expand Up @@ -167,7 +167,8 @@ irqreturn_t cx18_irq_handler(int irq, void *dev_id)
cx18_write_reg_expect(cx, hw2, HW2_INT_CLR_STATUS, ~hw2, hw2);

if (sw1 || sw2 || hw2)
CX18_DEBUG_HI_IRQ("SW1: %x SW2: %x HW2: %x\n", sw1, sw2, hw2);
CX18_DEBUG_HI_IRQ("received interrupts "
"SW1: %x SW2: %x HW2: %x\n", sw1, sw2, hw2);

/* To do: interrupt-based I2C handling
if (hw2 & (HW2_I2C1_INT|HW2_I2C2_INT)) {
Expand Down
130 changes: 62 additions & 68 deletions drivers/media/video/cx18/cx18-mailbox.c
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Original file line number Diff line number Diff line change
Expand Up @@ -92,48 +92,6 @@ static const struct cx18_api_info *find_api_info(u32 cmd)
return NULL;
}

static struct cx18_mailbox __iomem *cx18_mb_is_complete(struct cx18 *cx, int rpu,
u32 *state, u32 *irq, u32 *req)
{
struct cx18_mailbox __iomem *mb = NULL;
int wait_count = 0;
u32 ack;

switch (rpu) {
case APU:
mb = &cx->scb->epu2apu_mb;
*state = cx18_readl(cx, &cx->scb->apu_state);
*irq = cx18_readl(cx, &cx->scb->epu2apu_irq);
break;

case CPU:
mb = &cx->scb->epu2cpu_mb;
*state = cx18_readl(cx, &cx->scb->cpu_state);
*irq = cx18_readl(cx, &cx->scb->epu2cpu_irq);
break;

default:
break;
}

if (mb == NULL)
return mb;

do {
*req = cx18_readl(cx, &mb->request);
ack = cx18_readl(cx, &mb->ack);
wait_count++;
} while (*req != ack && wait_count < 600);

if (*req == ack) {
(*req)++;
if (*req == 0 || *req == 0xffffffff)
*req = 1;
return mb;
}
return NULL;
}

long cx18_mb_ack(struct cx18 *cx, const struct cx18_mailbox *mb, int rpu)
{
struct cx18_mailbox __iomem *ack_mb;
Expand Down Expand Up @@ -164,12 +122,13 @@ long cx18_mb_ack(struct cx18 *cx, const struct cx18_mailbox *mb, int rpu)
static int cx18_api_call(struct cx18 *cx, u32 cmd, int args, u32 data[])
{
const struct cx18_api_info *info = find_api_info(cmd);
u32 state = 0, irq = 0, req, oldreq, err;
u32 state, irq, req, ack, err;
struct cx18_mailbox __iomem *mb;
u32 __iomem *xpu_state;
wait_queue_head_t *waitq;
struct mutex *mb_lock;
int timeout = 100;
int sig = 0;
long unsigned int j, ret;
int i;

if (info == NULL) {
Expand All @@ -186,10 +145,16 @@ static int cx18_api_call(struct cx18 *cx, u32 cmd, int args, u32 data[])
case APU:
waitq = &cx->mb_apu_waitq;
mb_lock = &cx->epu2apu_mb_lock;
irq = IRQ_EPU_TO_APU;
mb = &cx->scb->epu2apu_mb;
xpu_state = &cx->scb->apu_state;
break;
case CPU:
waitq = &cx->mb_cpu_waitq;
mb_lock = &cx->epu2cpu_mb_lock;
irq = IRQ_EPU_TO_CPU;
mb = &cx->scb->epu2cpu_mb;
xpu_state = &cx->scb->cpu_state;
break;
default:
CX18_WARN("Unknown RPU (%d) for API call\n", info->rpu);
Expand All @@ -198,51 +163,85 @@ static int cx18_api_call(struct cx18 *cx, u32 cmd, int args, u32 data[])

mutex_lock(mb_lock);
cx18_setup_page(cx, SCB_OFFSET);
mb = cx18_mb_is_complete(cx, info->rpu, &state, &irq, &req);

if (mb == NULL) {
mutex_unlock(mb_lock);
CX18_ERR("mb %s busy\n", info->name);
return -EBUSY;
}
/*
* Wait for an in-use mailbox to complete
*
* If the XPU is responding with Ack's, the mailbox shouldn't be in
* a busy state, since we serialize access to it on our end.
*
* If the wait for ack after sending a previous command was interrupted
* by a signal, we may get here and find a busy mailbox. After waiting,
* mark it "not busy" from our end, if the XPU hasn't ack'ed it still.
*/
state = cx18_readl(cx, xpu_state);
req = cx18_readl(cx, &mb->request);
j = msecs_to_jiffies(timeout);
ret = wait_event_timeout(*waitq,
(ack = cx18_readl(cx, &mb->ack)) == req,
j);
if (req != ack) {
/* waited long enough, make the mbox "not busy" from our end */
cx18_writel(cx, req, &mb->ack);
CX18_ERR("mbox was found stuck busy when setting up for %s; "
"clearing busy and trying to proceed\n", info->name);
} else if (ret != j)
CX18_DEBUG_API("waited %u usecs for busy mbox to be acked\n",
jiffies_to_usecs(j-ret));

/* Build the outgoing mailbox */
req = ((req & 0xfffffffe) == 0xfffffffe) ? 1 : req + 1;

oldreq = req - 1;
cx18_writel(cx, cmd, &mb->cmd);
for (i = 0; i < args; i++)
cx18_writel(cx, data[i], &mb->args[i]);
cx18_writel(cx, 0, &mb->error);
cx18_writel(cx, req, &mb->request);
cx18_writel(cx, req - 1, &mb->ack); /* ensure ack & req are distinct */

/* Notify the XPU and wait for it to send an Ack back */
if (info->flags & API_FAST)
timeout /= 2;
j = msecs_to_jiffies(timeout);

CX18_DEBUG_HI_IRQ("sending interrupt SW1: %x to send %s\n",
irq, info->name);
cx18_write_reg_expect(cx, irq, SW1_INT_SET, irq, irq);

sig = wait_event_interruptible_timeout(
ret = wait_event_interruptible_timeout(
*waitq,
cx18_readl(cx, &mb->ack) == cx18_readl(cx, &mb->request),
msecs_to_jiffies(timeout));
if (sig == 0) {
j);
if (ret == 0) {
/* Timed out */
cx18_writel(cx, oldreq, &mb->request);
mutex_unlock(mb_lock);
CX18_ERR("sending %s timed out waiting for RPU to respond\n",
info->name);
CX18_ERR("sending %s timed out waiting for RPU "
"acknowledgement\n", info->name);
return -EINVAL;
} else if (sig < 0) {
} else if (ret < 0) {
/* Interrupted */
cx18_writel(cx, oldreq, &mb->request);
mutex_unlock(mb_lock);
CX18_WARN("sending %s interrupted waiting for RPU to respond\n",
info->name);
CX18_WARN("sending %s was interrupted waiting for RPU"
"acknowledgement\n", info->name);
return -EINTR;
}
} else if (ret != j)
CX18_DEBUG_HI_API("waited %u usecs for %s to be acked\n",
jiffies_to_usecs(j-ret), info->name);

/* Collect data returned by the XPU */
for (i = 0; i < MAX_MB_ARGUMENTS; i++)
data[i] = cx18_readl(cx, &mb->args[i]);
err = cx18_readl(cx, &mb->error);
mutex_unlock(mb_lock);

/*
* Wait for XPU to perform extra actions for the caller in some cases.
* e.g. CX18_CPU_DE_RELEASE_MDL will cause the CPU to send all buffers
* back in a burst shortly thereafter
*/
if (info->flags & API_SLOW)
cx18_msleep_timeout(300, 0);

if (err)
CX18_DEBUG_API("mailbox error %08x for command %s\n", err,
info->name);
Expand All @@ -251,12 +250,7 @@ static int cx18_api_call(struct cx18 *cx, u32 cmd, int args, u32 data[])

int cx18_api(struct cx18 *cx, u32 cmd, int args, u32 data[])
{
int res = cx18_api_call(cx, cmd, args, data);

/* Allow a single retry, probably already too late though.
If there is no free mailbox then that is usually an indication
of a more serious problem. */
return (res == -EBUSY) ? cx18_api_call(cx, cmd, args, data) : res;
return cx18_api_call(cx, cmd, args, data);
}

static int cx18_set_filter_param(struct cx18_stream *s)
Expand Down

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