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.
That's odd, it works for me:
$ git fetch linux-stable $ git checkout linux-stable/linux-5.2.y Checking out files: 100% (43562/43562), done. HEAD is now at 5697a9d... Linux 5.2.7 $ git am /tmp/pt Applying: spi: bcm2835: Fix 3-wire mode if DMA is enabled
Could you be a little more specific why it couldn't be applied when you tried it?
Thanks,
Lukas
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
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_controller *ctlr, 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 != ctlr->dummy_rx)