From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Date: Thu, 8 Aug 2019 10:01:18 +0000 (+0200)
Subject: 4.19-stable patches
X-Git-Tag: v5.2.8~5
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=4422279540deca4f77687cf41cea4fc6d1a26b8b;p=thirdparty%2Fkernel%2Fstable-queue.git

4.19-stable patches

added patches:
	spi-bcm2835-fix-3-wire-mode-if-dma-is-enabled.patch
---

diff --git a/queue-4.19/series b/queue-4.19/series
index 0490800a6cf..dc17fd070d4 100644
--- a/queue-4.19/series
+++ b/queue-4.19/series
@@ -42,3 +42,4 @@ cgroup-implement-css_task_iter_skip.patch
 cgroup-include-dying-leaders-with-live-threads-in-procs-iterations.patch
 cgroup-css_task_iter_skip-d-iterators-must-be-advanced-before-accessed.patch
 cgroup-fix-css_task_iter_advance_css_set-cset-skip-condition.patch
+spi-bcm2835-fix-3-wire-mode-if-dma-is-enabled.patch
diff --git a/queue-4.19/spi-bcm2835-fix-3-wire-mode-if-dma-is-enabled.patch b/queue-4.19/spi-bcm2835-fix-3-wire-mode-if-dma-is-enabled.patch
new file mode 100644
index 00000000000..23d517c12fb
--- /dev/null
+++ b/queue-4.19/spi-bcm2835-fix-3-wire-mode-if-dma-is-enabled.patch
@@ -0,0 +1,54 @@
+From 8d8bef50365847134b51c1ec46786bc2873e4e47 Mon Sep 17 00:00:00 2001
+From: Lukas Wunner <lukas@wunner.de>
+Date: Wed, 3 Jul 2019 12:29:31 +0200
+Subject: spi: bcm2835: Fix 3-wire mode if DMA is enabled
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+From: Lukas Wunner <lukas@wunner.de>
+
+commit 8d8bef50365847134b51c1ec46786bc2873e4e47 upstream.
+
+Commit 6935224da248 ("spi: bcm2835: enable support of 3-wire mode")
+added 3-wire support to the BCM2835 SPI driver by setting the REN bit
+(Read Enable) in the CS register when receiving data.  The REN bit puts
+the transmitter in high-impedance state.  The driver recognizes that
+data is to be received by checking whether the rx_buf of a transfer is
+non-NULL.
+
+Commit 3ecd37edaa2a ("spi: bcm2835: enable dma modes for transfers
+meeting certain conditions") subsequently broke 3-wire support because
+it set the SPI_MASTER_MUST_RX flag which causes spi_map_msg() to replace
+rx_buf with a dummy buffer if it is NULL.  As a result, rx_buf is
+*always* non-NULL if DMA is enabled.
+
+Reinstate 3-wire support by not only checking whether rx_buf is non-NULL,
+but also checking that it is not the dummy buffer.
+
+Fixes: 3ecd37edaa2a ("spi: bcm2835: enable dma modes for transfers meeting certain conditions")
+Reported-by: Nuno Sá <nuno.sa@analog.com>
+Signed-off-by: Lukas Wunner <lukas@wunner.de>
+Cc: stable@vger.kernel.org # v4.2+
+Cc: Martin Sperl <kernel@martin.sperl.org>
+Acked-by: Stefan Wahren <wahrenst@gmx.net>
+Link: https://lore.kernel.org/r/328318841455e505370ef8ecad97b646c033dc8a.1562148527.git.lukas@wunner.de
+Signed-off-by: Mark Brown <broonie@kernel.org>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+
+---
+ drivers/spi/spi-bcm2835.c |    3 ++-
+ 1 file changed, 2 insertions(+), 1 deletion(-)
+
+--- a/drivers/spi/spi-bcm2835.c
++++ b/drivers/spi/spi-bcm2835.c
+@@ -554,7 +554,8 @@ static int bcm2835_spi_transfer_one(stru
+ 	bcm2835_wr(bs, BCM2835_SPI_CLK, cdiv);
+ 
+ 	/* handle all the 3-wire mode */
+-	if ((spi->mode & SPI_3WIRE) && (tfr->rx_buf))
++	if (spi->mode & SPI_3WIRE && tfr->rx_buf &&
++	    tfr->rx_buf != master->dummy_rx)
+ 		cs |= BCM2835_SPI_CS_REN;
+ 	else
+ 		cs &= ~BCM2835_SPI_CS_REN;