tty: serial: pch_uart: correct usage of dma_unmap_sg
authorPeng Fan <peng.fan@nxp.com>
Wed, 13 Nov 2019 05:37:42 +0000 (05:37 +0000)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Thu, 23 Jan 2020 07:19:36 +0000 (08:19 +0100)
commit7afe9c3fb81dcd19f2f37b7c051c6a3d8ccfc5e7
tree1fc917c4b09ae19f98ed10022f9d24c320166f8c
parenta18a51a383a3e331bd72e8ce1b62a0fda4889f88
tty: serial: pch_uart: correct usage of dma_unmap_sg

commit 74887542fdcc92ad06a48c0cca17cdf09fc8aa00 upstream.

Per Documentation/DMA-API-HOWTO.txt,
To unmap a scatterlist, just call:
dma_unmap_sg(dev, sglist, nents, direction);

.. note::

The 'nents' argument to the dma_unmap_sg call must be
the _same_ one you passed into the dma_map_sg call,
it should _NOT_ be the 'count' value _returned_ from the
dma_map_sg call.

However in the driver, priv->nent is directly assigned with value
returned from dma_map_sg, and dma_unmap_sg use priv->nent for unmap,
this breaks the API usage.

So introduce a new entry orig_nent to remember 'nents'.

Fixes: da3564ee027e ("pch_uart: add multi-scatter processing")
Signed-off-by: Peng Fan <peng.fan@nxp.com>
Link: https://lore.kernel.org/r/1573623259-6339-1-git-send-email-peng.fan@nxp.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
drivers/tty/serial/pch_uart.c