Linux-SPI Archive on lore.kernel.org
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From: Lukas Wunner <lukas@wunner.de>
To: Mark Brown <broonie@kernel.org>
Cc: "Nicolas Saenz Julienne" <nsaenzjulienne@suse.de>,
	Martin Sperl <kernel@martin.sperl.org>,
	linux-spi@vger.kernel.org, linux-rpi-kernel@lists.infradead.org
Subject: [PATCH 4/5] spi: bcm2835: Tear down DMA before turning off SPI controller
Date: Fri, 15 May 2020 17:58:04 +0200
Message-ID: <ac79f1e3d6fd9a1f5e0cb4008c43b98ea70be3c2.1589557526.git.lukas@wunner.de> (raw)
In-Reply-To: <cover.1589557526.git.lukas@wunner.de>

On unbind of the BCM2835 SPI driver, the SPI controller is disabled
first and the DMA channels are terminated and torn down afterwards.

This seems backwards:  In the theoretical case that DMA is active,
it might try to fill the SPI FIFOs even after the controller has
been disabled.

Reverse the order, thereby mirroring what's done on ->probe().

Signed-off-by: Lukas Wunner <lukas@wunner.de>
---
 drivers/spi/spi-bcm2835.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/spi/spi-bcm2835.c b/drivers/spi/spi-bcm2835.c
index 06d2782d38ec..20d8581fdf88 100644
--- a/drivers/spi/spi-bcm2835.c
+++ b/drivers/spi/spi-bcm2835.c
@@ -1380,14 +1380,14 @@ static int bcm2835_spi_remove(struct platform_device *pdev)
 
 	spi_unregister_controller(ctlr);
 
+	bcm2835_dma_release(ctlr, bs);
+
 	/* Clear FIFOs, and disable the HW block */
 	bcm2835_wr(bs, BCM2835_SPI_CS,
 		   BCM2835_SPI_CS_CLEAR_RX | BCM2835_SPI_CS_CLEAR_TX);
 
 	clk_disable_unprepare(bs->clk);
 
-	bcm2835_dma_release(ctlr, bs);
-
 	return 0;
 }
 
-- 
2.26.2


  parent reply index

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-15 15:58 [PATCH 0/5] Raspberry Pi SPI unbind fixes Lukas Wunner
2020-05-15 15:58 ` [PATCH 1/5] spi: Fix controller unregister order Lukas Wunner
2020-05-15 16:27   ` Mark Brown
2020-05-15 16:31     ` Lukas Wunner
2020-05-15 21:37       ` Andy Shevchenko
2020-05-16  6:45         ` Lukas Wunner
2020-05-16  9:45           ` Andy Shevchenko
2020-05-15 15:58 ` [PATCH 2/5] spi: bcm2835: " Lukas Wunner
2020-05-15 16:29   ` Mark Brown
2020-05-15 16:44     ` Lukas Wunner
2020-05-15 21:33       ` Andy Shevchenko
2020-05-16  6:56         ` Lukas Wunner
2020-05-16  9:40           ` Andy Shevchenko
2020-05-15 15:58 ` [PATCH 3/5] spi: bcm2835aux: " Lukas Wunner
2020-05-15 15:58 ` Lukas Wunner [this message]
2020-05-15 15:58 ` [PATCH 5/5] spi: Document devm_spi_register_controller() gotcha Lukas Wunner
2020-05-15 16:30   ` Mark Brown
2020-05-20 17:17 ` [PATCH 0/5] Raspberry Pi SPI unbind fixes Mark Brown

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