linux-kernel - [PATCH v2 2/4] spi: s3c64xx: add cpu

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Date:   Wed, 19 Apr 2023 15:06:37 +0900
From:   Jaewon Kim <jaewon02.kim@...sung.com>
To:     Mark Brown <broonie@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
        Andi Shyti <andi@...zian.org>,
        Alim Akhtar <alim.akhtar@...sung.com>
Cc:     linux-spi@...r.kernel.org, linux-samsung-soc@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Chanho Park <chanho61.park@...sung.com>,
        Jaewon Kim <jaewon02.kim@...sung.com>
Subject: [PATCH v2 2/4] spi: s3c64xx: add cpu_relax in polling loop

Adds cpu_relax() to prevent long busy-wait.
There is busy-wait loop to check data transfer completion in polling mode.

Signed-off-by: Jaewon Kim <jaewon02.kim@...sung.com>
---
 drivers/spi/spi-s3c64xx.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/spi/spi-s3c64xx.c b/drivers/spi/spi-s3c64xx.c
index 273aa02322d9..886722fb40ea 100644
--- a/drivers/spi/spi-s3c64xx.c
+++ b/drivers/spi/spi-s3c64xx.c
@@ -568,6 +568,7 @@ static int s3c64xx_wait_for_pio(struct s3c64xx_spi_driver_data *sdd,
 
 	val = msecs_to_loops(ms);
 	do {
+		cpu_relax();
 		status = readl(regs + S3C64XX_SPI_STATUS);
 	} while (RX_FIFO_LVL(status, sdd) < xfer->len && --val);
 
-- 
2.17.1