From 29bef79908459d20a7a3db654bceb8f3ce4601dc Mon Sep 17 00:00:00 2001 From: Robert Baldyga Date: Wed, 10 Dec 2014 12:49:26 +0100 Subject: [PATCH] serial: samsung: add DMA support for TX Add TX DMA transfers support for samsung serial driver. It's enabled when "dmas" property is defined in serial device-tree node, otherwise TX transfers are prerformed using PIO. TX DMA is used for data segments larger than fifosize to reduce number of interrupts during data transmission. For buffers shorter than fifosize PIO mode is selected. Data blocks for DMA transfers are aligned to cache line size to avoid problems with coherency (some areas of TX circ buffer can be used by CPU during DMA transaction, so we have to ensure that our data is always consistent). Based on previous work of Sylwester Nawrocki and Lukasz Czerwinski. Signed-off-by: Robert Baldyga Signed-off-by: Greg Kroah-Hartman --- Reading git-format-patch failed