Unverified Commit 531860e1 authored by David Lechner's avatar David Lechner Committed by Mark Brown
Browse files

spi: axi-spi-engine: remove use of ida for sync id 



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: default avatarNuno Sa <nuno.sa@analog.com>
Signed-off-by: default avatarDavid Lechner <dlechner@baylibre.com>
Link: https://lore.kernel.org/r/20240207-axi-spi-engine-round-2-1-v2-1-40c0b4e85352@baylibre.com


Signed-off-by: default avatarMark Brown <broonie@kernel.org>
parent c0c0293c

drivers/spi/spi-axi-spi-engine.c

+6 −22
Original line number Diff line number Diff line
@@ -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;