linux-kernel - [PATCH 4.16 027/196] spi: atmel: init FIFOs before spi enable

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Date:   Sun, 22 Apr 2018 15:50:47 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Eugen Hristev <eugen.hristev@...rochip.com>,
        Nicolas Ferre <nicolas.ferre@...rochip.com>,
        Mark Brown <broonie@...nel.org>
Subject: [PATCH 4.16 027/196] spi: atmel: init FIFOs before spi enable

4.16-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Eugen Hristev <eugen.hristev@...rochip.com>

commit 9581329eff9db72ab4fbb46a594fd7fdda3c51b0 upstream.

The datasheet recommends initializing FIFOs before
SPI enable. If we do not do it like this, there may be
a strange behavior. We noticed that DMA does not work properly
with FIFOs if we do not clear them beforehand or enable them
before SPIEN.

Signed-off-by: Eugen Hristev <eugen.hristev@...rochip.com>
Acked-by: Nicolas Ferre <nicolas.ferre@...rochip.com>
Signed-off-by: Mark Brown <broonie@...nel.org>
Cc: stable@...r.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/spi/spi-atmel.c |    8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

--- a/drivers/spi/spi-atmel.c
+++ b/drivers/spi/spi-atmel.c
@@ -1512,6 +1512,11 @@ static void atmel_spi_init(struct atmel_
 {
 	spi_writel(as, CR, SPI_BIT(SWRST));
 	spi_writel(as, CR, SPI_BIT(SWRST)); /* AT91SAM9263 Rev B workaround */
+
+	/* It is recommended to enable FIFOs first thing after reset */
+	if (as->fifo_size)
+		spi_writel(as, CR, SPI_BIT(FIFOEN));
+
 	if (as->caps.has_wdrbt) {
 		spi_writel(as, MR, SPI_BIT(WDRBT) | SPI_BIT(MODFDIS)
 				| SPI_BIT(MSTR));
@@ -1522,9 +1527,6 @@ static void atmel_spi_init(struct atmel_
 	if (as->use_pdc)
 		spi_writel(as, PTCR, SPI_BIT(RXTDIS) | SPI_BIT(TXTDIS));
 	spi_writel(as, CR, SPI_BIT(SPIEN));
-
-	if (as->fifo_size)
-		spi_writel(as, CR, SPI_BIT(FIFOEN));
 }
 
 static int atmel_spi_probe(struct platform_device *pdev)