Unverified Commit d67396c9 authored by Mateusz Litwin's avatar Mateusz Litwin Committed by Mark Brown
Browse files

spi: cadence-quadspi: Prevent lost complete() call during indirect read 



A race condition exists between the read loop and IRQ `complete()` call.
An interrupt could call the complete() between the inner loop and
reinit_completion(), potentially losing the completion event and causing
an unnecessary timeout. Moving reinit_completion() before the loop
prevents this. A premature signal will only result in a spurious wakeup
and another wait cycle, which is preferable to waiting for a timeout.

Signed-off-by: default avatarMateusz Litwin <mateusz.litwin@nokia.com>
Link: https://patch.msgid.link/20251218-cqspi_indirect_read_improve-v2-1-396079972f2a@nokia.com


Signed-off-by: default avatarMark Brown <broonie@kernel.org>
parent 9448598b

drivers/spi/spi-cadence-quadspi.c

+9 −1
Original line number Diff line number Diff line
@@ -769,6 +769,7 @@ static int cqspi_indirect_read_execute(struct cqspi_flash_pdata *f_pdata, 
	readl(reg_base + CQSPI_REG_INDIRECTRD); /* Flush posted write. */



	while (remaining > 0) {

		ret = 0;

		if (use_irq &&

		    !wait_for_completion_timeout(&cqspi->transfer_complete,

						 msecs_to_jiffies(CQSPI_READ_TIMEOUT_MS)))
@@ -781,6 +782,14 @@ static int cqspi_indirect_read_execute(struct cqspi_flash_pdata *f_pdata, 
		if (cqspi->slow_sram)

			writel(0x0, reg_base + CQSPI_REG_IRQMASK);



		/*

		 * Prevent lost interrupt and race condition by reinitializing early.

		 * A spurious wakeup and another wait cycle can occur here,

		 * which is preferable to waiting until timeout if interrupt is lost.

		 */

		if (use_irq)

			reinit_completion(&cqspi->transfer_complete);



		bytes_to_read = cqspi_get_rd_sram_level(cqspi);



		if (ret && bytes_to_read == 0) {
@@ -813,7 +822,6 @@ static int cqspi_indirect_read_execute(struct cqspi_flash_pdata *f_pdata, 
		}



		if (use_irq && remaining > 0) {

			reinit_completion(&cqspi->transfer_complete);

			if (cqspi->slow_sram)

				writel(CQSPI_REG_IRQ_WATERMARK, reg_base + CQSPI_REG_IRQMASK);

		}