Patch "spi: sun4i: fix FIFO limit" has been added to the 4.4-stable tree

Patch "spi: sun4i: fix FIFO limit" has been added to the 4.4-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    spi: sun4i: fix FIFO limit

to the 4.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     spi-sun4i-fix-fifo-limit.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 6d9fe44bd73d567d04d3a68a2d2fa521ab9532f2 Mon Sep 17 00:00:00 2001
From: Michal Suchanek <hramrach@gmail.com>
Date: Mon, 13 Jun 2016 17:46:49 +0000
Subject: spi: sun4i: fix FIFO limit

From: Michal Suchanek <hramrach@gmail.com>

commit 6d9fe44bd73d567d04d3a68a2d2fa521ab9532f2 upstream.

When testing SPI without DMA I noticed that filling the FIFO on the
spi controller causes timeout.

Always leave room for one byte in the FIFO.

Signed-off-by: Michal Suchanek <hramrach@gmail.com>
Acked-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/spi/spi-sun4i.c |   13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

--- a/drivers/spi/spi-sun4i.c
+++ b/drivers/spi/spi-sun4i.c
@@ -177,7 +177,10 @@ static int sun4i_spi_transfer_one(struct
 
 	/* We don't support transfer larger than the FIFO */
 	if (tfr->len > SUN4I_FIFO_DEPTH)
-		return -EINVAL;
+		return -EMSGSIZE;
+
+	if (tfr->tx_buf && tfr->len >= SUN4I_FIFO_DEPTH)
+		return -EMSGSIZE;
 
 	reinit_completion(&sspi->done);
 	sspi->tx_buf = tfr->tx_buf;
@@ -270,8 +273,12 @@ static int sun4i_spi_transfer_one(struct
 	sun4i_spi_write(sspi, SUN4I_BURST_CNT_REG, SUN4I_BURST_CNT(tfr->len));
 	sun4i_spi_write(sspi, SUN4I_XMIT_CNT_REG, SUN4I_XMIT_CNT(tx_len));
 
-	/* Fill the TX FIFO */
-	sun4i_spi_fill_fifo(sspi, SUN4I_FIFO_DEPTH);
+	/*
+	 * Fill the TX FIFO
+	 * Filling the FIFO fully causes timeout for some reason
+	 * at least on spi2 on A10s
+	 */
+	sun4i_spi_fill_fifo(sspi, SUN4I_FIFO_DEPTH - 1);
 
 	/* Enable the interrupts */
 	sun4i_spi_write(sspi, SUN4I_INT_CTL_REG, SUN4I_INT_CTL_TC);


Patches currently in stable-queue which might be from hramrach@gmail.com are

queue-4.4/spi-sun4i-fix-fifo-limit.patch
queue-4.4/spi-sunxi-fix-transfer-timeout.patch