From 8f0bcbcab016324c2a3ba4cc715e8e523c29a578 Mon Sep 17 00:00:00 2001 From: Mark Salter Date: Wed, 12 Dec 2012 15:36:38 +0000 Subject: [PATCH] MN10300: fix SMP synchronization between txdma and serial driver The SoC serial port driver uses a high priority interrupt to handle tx of characters in the tx ring buffer. The driver needs to disable/enable this IRQ from outside of irq context. The original code to do this is not foolproof on SMP machines because the IRQ running on one core could still access the serial port for a short time after the driver running on another core disables the interrupt. This patch adds a flag to tell the IRQ handler that the driver wants to disable the interrupt. After seeing the flag, the IRQ handler will immediately disable the interrupt and exit. After setting the flag, the driver will wait for interrupt to be disabled by the IRQ handler. Signed-off-by: Mark Salter Signed-off-by: David Howells --- Reading git-format-patch failed