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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Lukas Wunner <lukas@wunner.de>,
        Mathias Duckeck <m.duckeck@kunbus.de>,
        Frank Pavlic <f.pavlic@kunbus.de>,
        Martin Sperl <kernel@martin.sperl.org>,
        =?UTF-8?q?Noralf=20Tr=C3=B8nnes?= <noralf@tronnes.org>,
        Mark Brown <broonie@kernel.org>
Subject: [PATCH 4.20 081/145] spi: bcm2835: Fix book-keeping of DMA termination
Date:   Mon,  7 Jan 2019 13:31:58 +0100
Message-Id: <20190107104447.824068213@linuxfoundation.org>
In-Reply-To: <20190107104437.308206189@linuxfoundation.org>
References: <20190107104437.308206189@linuxfoundation.org>
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4.20-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Lukas Wunner <lukas@wunner.de>

commit dbc944115eed48af110646992893dc43321368d8 upstream.

If submission of a DMA TX transfer succeeds but submission of the
corresponding RX transfer does not, the BCM2835 SPI driver terminates
the TX transfer but neglects to reset the dma_pending flag to false.

Thus, if the next transfer uses interrupt mode (because it is shorter
than BCM2835_SPI_DMA_MIN_LENGTH) and runs into a timeout,
dmaengine_terminate_all() will be called both for TX (once more) and
for RX (which was never started in the first place).  Fix it.

Signed-off-by: Lukas Wunner <lukas@wunner.de>
Fixes: 3ecd37edaa2a ("spi: bcm2835: enable dma modes for transfers meeting certain conditions")
Cc: stable@vger.kernel.org # v4.2+
Cc: Mathias Duckeck <m.duckeck@kunbus.de>
Cc: Frank Pavlic <f.pavlic@kunbus.de>
Cc: Martin Sperl <kernel@martin.sperl.org>
Cc: Noralf Trønnes <noralf@tronnes.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/spi/spi-bcm2835.c |    1 +
 1 file changed, 1 insertion(+)

--- a/drivers/spi/spi-bcm2835.c
+++ b/drivers/spi/spi-bcm2835.c
@@ -341,6 +341,7 @@ static int bcm2835_spi_transfer_one_dma(
 	if (ret) {
 		/* need to reset on errors */
 		dmaengine_terminate_all(master->dma_tx);
+		bs->dma_pending = false;
 		bcm2835_spi_reset_hw(master);
 		return ret;
 	}