[PATCH 22/30] staging: nvec: Allow TX buffers only in the lower 75% of the pool
Julian Andres Klode
jak at jak-linux.org
Fri Sep 23 16:38:14 UTC 2011
Allow TX buffers to be allocated only in the lower 75% of the pool
to avoid a completely filled buffer preventing the driver from
processing responses.
Signed-off-by: Julian Andres Klode <jak at jak-linux.org>
---
drivers/staging/nvec/nvec.c | 32 +++++++++++++++++++++++++++-----
1 files changed, 27 insertions(+), 5 deletions(-)
diff --git a/drivers/staging/nvec/nvec.c b/drivers/staging/nvec/nvec.c
index 34b9c11..13934d9 100644
--- a/drivers/staging/nvec/nvec.c
+++ b/drivers/staging/nvec/nvec.c
@@ -62,6 +62,16 @@
#define I2C_SL_ADDR2 0x30
#define I2C_SL_DELAY_COUNT 0x3c
+/**
+ * enum nvec_msg_category - Message categories for nvec_msg_alloc()
+ * @NVEC_MSG_RX: The message is an incoming message (from EC)
+ * @NVEC_MSG_TX: The message is an outgoing message (to EC)
+ */
+enum nvec_msg_category {
+ NVEC_MSG_RX,
+ NVEC_MSG_TX,
+};
+
static const unsigned char EC_DISABLE_EVENT_REPORTING[3] = "\x04\x00\x00";
static const unsigned char EC_ENABLE_EVENT_REPORTING[3] = "\x04\x00\x01";
static const unsigned char EC_GET_FIRMWARE_VERSION[2] = "\x07\x15";
@@ -135,21 +145,32 @@ static int nvec_status_notifier(struct notifier_block *nb,
/**
* nvec_msg_alloc:
* @nvec: A &struct nvec_chip
+ * @category: Pool category, see &enum nvec_msg_category
*
* Allocate a single &struct nvec_msg object from the message pool of
* @nvec. The result shall be passed to nvec_msg_free() if no longer
* used.
+ *
+ * Outgoing messages are placed in the lower 75% of the pool, keeping the
+ * upper 25% available for RX buffers only. The reason is to prevent a
+ * situation where all buffers are full and a message is thus endlessly
+ * retried because the response could never be processed.
*/
-static struct nvec_msg *nvec_msg_alloc(struct nvec_chip *nvec)
+static struct nvec_msg *nvec_msg_alloc(struct nvec_chip *nvec,
+ enum nvec_msg_category category)
{
size_t i;
- for (i = 0; i < NVEC_POOL_SIZE; i++)
+ size_t max = NVEC_POOL_SIZE;
+ if (category == NVEC_MSG_TX)
+ max = 3 * max / 4;
+ for (i = 0; i < max ; i++)
if (atomic_xchg(&nvec->msg_pool[i].used, 1) == 0) {
dev_vdbg(nvec->dev, "INFO: Alloc %u\n", (uint) i);
return &nvec->msg_pool[i];
}
- dev_err(nvec->dev, "could not allocate buffer\n");
+ dev_err(nvec->dev, "could not allocate %s buffer\n",
+ (category == NVEC_MSG_TX) ? "TX" : "RX");
return NULL;
}
@@ -231,7 +252,8 @@ int nvec_write_async(struct nvec_chip *nvec, const unsigned char *data,
struct nvec_msg *msg;
unsigned long flags;
- msg = nvec_msg_alloc(nvec);
+ msg = nvec_msg_alloc(nvec, NVEC_MSG_TX);
+
if (msg == NULL)
return -ENOMEM;
@@ -535,7 +557,7 @@ static irqreturn_t nvec_interrupt(int irq, void *dev)
if (status != I2C_SL_IRQ) {
nvec_invalid_flags(nvec, status, true);
} else {
- nvec->rx = nvec_msg_alloc(nvec);
+ nvec->rx = nvec_msg_alloc(nvec, NVEC_MSG_RX);
nvec->rx->data[0] = received;
nvec->rx->pos = 1;
nvec->state = 2;
--
1.7.5.4
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