linux-kernel - [PATCH] spi: cadence: Add usleep_range() for cdns_spi_fill_tx

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Date:   Mon,  9 Apr 2018 19:16:50 +0800
From:   sxauwsk <sxauwsk@....com>
To:     Mark Brown <broonie@...nel.org>
Cc:     linux-spi@...r.kernel.org, linux-kernel@...r.kernel.org,
        sxauwsk@....com, guojian <guojian@...oinstrument.net>,
        wangshikai <wangshikai@...o-instrument.cn>
Subject: [PATCH] spi: cadence: Add usleep_range() for cdns_spi_fill_tx_fifo()

In case of xspi work in busy condition, may send bytes failed.
Add one bytes delay

Signed-off-by: sxauwsk <sxauwsk@....com>
Signed-off-by: guojian <guojian@...oinstrument.net>
Signed-off-by: wangshikai <wangshikai@...o-instrument.cn>
---
 drivers/spi/spi-cadence.c |    6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/spi/spi-cadence.c b/drivers/spi/spi-cadence.c
index 5c9516a..66ae055 100644
--- a/drivers/spi/spi-cadence.c
+++ b/drivers/spi/spi-cadence.c
@@ -313,6 +313,12 @@ static void cdns_spi_fill_tx_fifo(struct cdns_spi *xspi)
 
 	while ((trans_cnt < CDNS_SPI_FIFO_DEPTH) &&
 	       (xspi->tx_bytes > 0)) {
+
+		/* When xspi in busy condition, bytes may send failed,
+		 * caused communication failure so add one byte delay
+		 */
+		usleep_range(10, 20);
+
 		if (xspi->txbuf)
 			cdns_spi_write(xspi, CDNS_SPI_TXD, *xspi->txbuf++);
 		else
-- 
1.7.9.5