From 42f752b3fbcfee9c27e4f6f6216e60e130ba98c8 Mon Sep 17 00:00:00 2001
From: Dirk Behme <dirk.behme@de.bosch.com>
Date: Tue, 9 Dec 2014 18:11:28 +0900
Subject: [PATCH] serial: imx: use dma_is_txing to synchronize dma_tx_callback
 and imx_dma_tx

To synchronize between dma_tx_callback() and imx_dma_tx() use the same
variable, dma_is_txing. This prevents any race between these two functions
and ensures that a new DMA can start only after the first has been
finished.

Before the new DMA can be set up, update the circular buffer logic, first.
Therefore, change dma_is_txing after that update, instead of before.

While doing this, in dma_tx_callback() extend the locking to dma_unmap_sg()
and the update of dma_is_txing.

Signed-off-by: Dirk Behme <dirk.behme@de.bosch.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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