From ac50441720332f22a9d85ac03151d6acb7bc55d6 Mon Sep 17 00:00:00 2001
From: Andy Walls <awalls@radix.net>
Date: Fri, 7 Nov 2008 23:57:46 -0300
Subject: [PATCH] V4L/DVB (9595): cx18: Improve handling of outgoing mailboxes
detected 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>
---
drivers/media/video/cx18/cx18-irq.c | 3 +-
drivers/media/video/cx18/cx18-mailbox.c | 130 +++++++++++-------------
2 files changed, 64 insertions(+), 69 deletions(-)
diff --git a/drivers/media/video/cx18/cx18-irq.c b/drivers/media/video/cx18/cx18-irq.c
index 37b931055d3a1..4912b3c8e6a58 100644
--- a/drivers/media/video/cx18/cx18-irq.c
+++ b/drivers/media/video/cx18/cx18-irq.c
@@ -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)) {
diff --git a/drivers/media/video/cx18/cx18-mailbox.c b/drivers/media/video/cx18/cx18-mailbox.c
index d2975a2e6cb7f..0de4b9a7bbca9 100644
--- a/drivers/media/video/cx18/cx18-mailbox.c
+++ b/drivers/media/video/cx18/cx18-mailbox.c
@@ -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;
@@ -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) {
@@ -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);
@@ -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);
@@ -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)
--
2.30.2