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@linuxfoundation.org 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@wunner.de Date: Wed, 3 Jul 2019 12:29:31 +0200 Subject: [PATCH] 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
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.156214852... Signed-off-by: Mark Brown broonie@kernel.org
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;