Profiling has shown that ida_alloc_range() accounts for about 10% of the
time spent in spi_sync() when using the AXI SPI Engine controller. This
call is used to create a unique id for each SPI message to match to an
IRQ when the message is complete.
Since the core SPI code serializes messages in a message queue, we can
only have one message in flight at a time, namely host->cur_msg. This
means that we can use a fixed value instead of a unique id for each
message since there can never be more than one message pending at a
time.
This patch removes the use of ida for the sync id and replaces it with a
constant value. This simplifies the driver and improves performance.
Reviewed-by: Nuno Sa <[email protected]>
Signed-off-by: David Lechner <[email protected]>
---
drivers/spi/spi-axi-spi-engine.c | 28 ++++++----------------------
1 file changed, 6 insertions(+), 22 deletions(-)
diff --git a/drivers/spi/spi-axi-spi-engine.c b/drivers/spi/spi-axi-spi-engine.c
index 6b0c72bf3395..606389566129 100644
--- a/drivers/spi/spi-axi-spi-engine.c
+++ b/drivers/spi/spi-axi-spi-engine.c
@@ -7,7 +7,6 @@
#include <linux/clk.h>
#include <linux/fpga/adi-axi-common.h>
-#include <linux/idr.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/of.h>
@@ -57,6 +56,9 @@
#define SPI_ENGINE_TRANSFER_WRITE 0x1
#define SPI_ENGINE_TRANSFER_READ 0x2
+/* Arbitrary sync ID for use by host->cur_msg */
+#define AXI_SPI_ENGINE_CUR_MSG_SYNC_ID 0x1
+
#define SPI_ENGINE_CMD(inst, arg1, arg2) \
(((inst) << 12) | ((arg1) << 8) | (arg2))
@@ -98,8 +100,6 @@ struct spi_engine_message_state {
unsigned int rx_length;
/** @rx_buf: Bytes not yet written to the RX FIFO. */
uint8_t *rx_buf;
- /** @sync_id: ID to correlate SYNC interrupts with this message. */
- u8 sync_id;
};
struct spi_engine {
@@ -109,7 +109,6 @@ struct spi_engine {
spinlock_t lock;
void __iomem *base;
- struct ida sync_ida;
struct timer_list watchdog_timer;
struct spi_controller *controller;
@@ -483,9 +482,7 @@ static irqreturn_t spi_engine_irq(int irq, void *devid)
}
if (pending & SPI_ENGINE_INT_SYNC && msg) {
- struct spi_engine_message_state *st = msg->state;
-
- if (completed_id == st->sync_id) {
+ if (completed_id == AXI_SPI_ENGINE_CUR_MSG_SYNC_ID) {
if (timer_delete_sync(&spi_engine->watchdog_timer)) {
msg->status = 0;
msg->actual_length = msg->frame_length;
@@ -510,10 +507,8 @@ static int spi_engine_prepare_message(struct spi_controller *host,
struct spi_message *msg)
{
struct spi_engine_program p_dry, *p;
- struct spi_engine *spi_engine = spi_controller_get_devdata(host);
struct spi_engine_message_state *st;
size_t size;
- int ret;
st = kzalloc(sizeof(*st), GFP_KERNEL);
if (!st)
@@ -531,18 +526,10 @@ static int spi_engine_prepare_message(struct spi_controller *host,
return -ENOMEM;
}
- ret = ida_alloc_range(&spi_engine->sync_ida, 0, U8_MAX, GFP_KERNEL);
- if (ret < 0) {
- kfree(p);
- kfree(st);
- return ret;
- }
-
- st->sync_id = ret;
-
spi_engine_compile_message(msg, false, p);
- spi_engine_program_add_cmd(p, false, SPI_ENGINE_CMD_SYNC(st->sync_id));
+ spi_engine_program_add_cmd(p, false, SPI_ENGINE_CMD_SYNC(
+ AXI_SPI_ENGINE_CUR_MSG_SYNC_ID));
st->p = p;
st->cmd_buf = p->instructions;
@@ -555,10 +542,8 @@ static int spi_engine_prepare_message(struct spi_controller *host,
static int spi_engine_unprepare_message(struct spi_controller *host,
struct spi_message *msg)
{
- struct spi_engine *spi_engine = spi_controller_get_devdata(host);
struct spi_engine_message_state *st = msg->state;
- ida_free(&spi_engine->sync_ida, st->sync_id);
kfree(st->p);
kfree(st);
@@ -640,7 +625,6 @@ static int spi_engine_probe(struct platform_device *pdev)
spi_engine = spi_controller_get_devdata(host);
spin_lock_init(&spi_engine->lock);
- ida_init(&spi_engine->sync_ida);
timer_setup(&spi_engine->watchdog_timer, spi_engine_timeout, TIMER_IRQSAFE);
spi_engine->controller = host;
--
2.43.0