On Thu, Aug 08, 2019 at 07:56:25AM +0200, Greg KH wrote:
> On Wed, Aug 07, 2019 at 10:58:49PM +0200, Lukas Wunner wrote:
> > On Wed, Aug 07, 2019 at 06:48:07PM +0200, gregkh@xxxxxxxxxxxxxxxxxxx wrote:
> > > The patch below does not apply to the 5.2-stable tree.
>
> The patch applies everywhere, but breaks the build in all trees.
Ugh, yes you are right, my apologies.
The reason is that v5.3 converted spi-bcm2835.c to use the
"spi_controller" nomenclature instead of "spi_master" with
commit 5f336ea53b6b ("spi: bcm2835: Replace spi_master by
spi_controller").
The replacement patch below should hopefully not break the
build. It's the same as upstream commit 8d8bef503658,
except one occurrence of "ctlr" is replaced by "master".
Thanks!
-- >8 --
>From 8d8bef50365847134b51c1ec46786bc2873e4e47 Mon Sep 17 00:00:00 2001
From: Lukas Wunner <lukas@xxxxxxxxx>
Date: Wed, 3 Jul 2019 12:29:31 +0200
Subject: [PATCH] spi: bcm2835: Fix 3-wire mode if DMA is enabled
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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@xxxxxxxxxx>
Signed-off-by: Lukas Wunner <lukas@xxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx # v4.2+
Cc: Martin Sperl <kernel@xxxxxxxxxxxxxxxx>
Acked-by: Stefan Wahren <wahrenst@xxxxxxx>
Link: https://lore.kernel.org/r/328318841455e505370ef8ecad97b646c033dc8a.1562148527.git.lukas@xxxxxxxxx
Signed-off-by: Mark Brown <broonie@xxxxxxxxxx>
diff --git a/drivers/spi/spi-bcm2835.c b/drivers/spi/spi-bcm2835.c
index 6f243a90c844..840b1b8ff3dc 100644
--- a/drivers/spi/spi-bcm2835.c
+++ b/drivers/spi/spi-bcm2835.c
@@ -834,7 +834,8 @@ static int bcm2835_spi_transfer_one(struct spi_master *master,
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;
