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SubjectRe: [PATCH 1/2] spi: axi-spi-engine: remove use of ida for sync id
From
Le 06/02/2024 à 21:31, David Lechner a écrit :
> 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...

So, maybe #include <linux/idr.h> can be removed as well?
(untested)



Also, even if unrelated to your changes, spi_engine_prepare_message()
could use struct_size() in:

size = sizeof(*p->instructions) * (p_dry.length + 1);
p = kzalloc(sizeof(*p) + size, GFP_KERNEL);

-->
p = kzalloc(struct_size(p, instructions, p_dry.length + 1, GFP_KERNEL);

which can be a little safer and less verbose.

CJ

> ...for the sync id and replaces it with a
> constant value. This simplifies the driver and improves performance.
>
> Signed-off-by: David Lechner <dlechner-rdvid1DuHRBWk0Htik3J/w@public.gmane.org>
> ---
> drivers/spi/spi-axi-spi-engine.c | 27 ++++++---------------------
> 1 file changed, 6 insertions(+), 21 deletions(-)
>
> diff --git a/drivers/spi/spi-axi-spi-engine.c b/drivers/spi/spi-axi-spi-engine.c
> index 6b0c72bf3395..9cc602075c17 100644
> --- a/drivers/spi/spi-axi-spi-engine.c
> +++ b/drivers/spi/spi-axi-spi-engine.c
> @@ -57,6 +57,9 @@
> #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 +101,6 @@ 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 +110,6 @@ struct spi_engine {
> spinlock_t lock;
>
> void __iomem *base;
> - struct ida sync_ida;
> struct timer_list watchdog_timer;
> struct spi_controller *controller;
>
> @@ -483,9 +483,7 @@ 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 +508,8 @@ 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 +527,10 @@ 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 +543,8 @@ 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 +626,6 @@ 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;
>
>


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