Patch "spi: imx: read back the RX/TX watermark levels earlier" has been added to the 4.0-stable tree

This is a note to let you know that I've just added the patch titled

spi: imx: read back the RX/TX watermark levels earlier

to the 4.0-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
spi-imx-read-back-the-rx-tx-watermark-levels-earlier.patch
and it can be found in the queue-4.0 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Lucas Stach <[email protected]>
Date: Wed, 1 Apr 2015 10:46:15 +0200
Subject: spi: imx: read back the RX/TX watermark levels earlier

From: Lucas Stach <[email protected]>

commit f511ab09dfb0fe7b2335eccac51ff9f001a32e4a upstream.

They are used to decide if the controller can do DMA on a buffer of a specific length and thus are needed before any transfer is attempted.

This fixes a memory leak where the SPI core uses the drivers can_dma() callback to determine if a buffer needs to be mapped. As the watermark levels aren't correct at that point the driver falsely claims to be able to DMA the buffer when it fact it isn't.
After the transfer has been done the core uses the same callback to determine if it needs to unmap the buffers. As the driver now correctly claims to not being able to DMA the buffer the core doesn't attempt to unmap the buffer which leaves the SGT leaking.

---
 drivers/spi/spi-imx.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

@@ -370,8 +370,6 @@ static int __maybe_unused mx51_ecspi_con
 	if (spi_imx->dma_is_inited) {
 		dma = readl(spi_imx->base + MX51_ECSPI_DMA);
 
-		spi_imx->tx_wml = spi_imx_get_fifosize(spi_imx) / 2;
-		spi_imx->rx_wml = spi_imx_get_fifosize(spi_imx) / 2;
 		spi_imx->rxt_wml = spi_imx_get_fifosize(spi_imx) / 2;
 		rx_wml_cfg = spi_imx->rx_wml << MX51_ECSPI_DMA_RX_WML_OFFSET;
 		tx_wml_cfg = spi_imx->tx_wml << MX51_ECSPI_DMA_TX_WML_OFFSET;

@@ -868,6 +866,8 @@ static int spi_imx_sdma_init(struct devi
 	master->max_dma_len = MAX_SDMA_BD_BYTES;
 	spi_imx->bitbang.master->flags = SPI_MASTER_MUST_RX |
 					 SPI_MASTER_MUST_TX;
+	spi_imx->tx_wml = spi_imx_get_fifosize(spi_imx) / 2;
+	spi_imx->rx_wml = spi_imx_get_fifosize(spi_imx) / 2;
 	spi_imx->dma_is_inited = 1;
 
 	return 0;

Patches currently in stable-queue which might be from [email protected] are

queue-4.0/spi-imx-read-back-the-rx-tx-watermark-levels-earlier.patch