From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tony Lindgren Subject: [PATCH 1/8] omap: Fix race condition in omap dma driver Date: Tue, 10 Nov 2009 19:00:32 -0800 Message-ID: <20091111030032.31793.59189.stgit@localhost> References: <20091111025907.31793.84134.stgit@localhost> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Return-path: Received: from mho-02-ewr.mailhop.org ([204.13.248.72]:55063 "EHLO mho-02-ewr.mailhop.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753132AbZKKDA3 (ORCPT ); Tue, 10 Nov 2009 22:00:29 -0500 In-Reply-To: <20091111025907.31793.84134.stgit@localhost> Sender: linux-omap-owner@vger.kernel.org List-Id: linux-omap@vger.kernel.org To: linux-arm-kernel@lists.infradead.org Cc: Fei Yang , linux-omap@vger.kernel.org, Tao Hu From: Tao Hu The bug could cause irq enable bit of one DMA channel is cleared/set unexpectedly when 2 (or more) drivers are calling omap_request_dma()/omap_free_dma() simultaneously Signed-off-by: Fei Yang Signed-off-by: Tao Hu Signed-off-by: Tony Lindgren --- arch/arm/plat-omap/dma.c | 6 ++++++ 1 files changed, 6 insertions(+), 0 deletions(-) diff --git a/arch/arm/plat-omap/dma.c b/arch/arm/plat-omap/dma.c index b53125f..02ed945 100644 --- a/arch/arm/plat-omap/dma.c +++ b/arch/arm/plat-omap/dma.c @@ -691,13 +691,16 @@ static inline void disable_lnk(int lch) static inline void omap2_enable_irq_lch(int lch) { u32 val; + unsigned long flags; if (!cpu_class_is_omap2()) return; + spin_lock_irqsave(&dma_chan_lock, flags); val = dma_read(IRQENABLE_L0); val |= 1 << lch; dma_write(val, IRQENABLE_L0); + spin_unlock_irqrestore(&dma_chan_lock, flags); } int omap_request_dma(int dev_id, const char *dev_name, @@ -799,10 +802,13 @@ void omap_free_dma(int lch) if (cpu_class_is_omap2()) { u32 val; + + spin_lock_irqsave(&dma_chan_lock, flags); /* Disable interrupts */ val = dma_read(IRQENABLE_L0); val &= ~(1 << lch); dma_write(val, IRQENABLE_L0); + spin_unlock_irqrestore(&dma_chan_lock, flags); /* Clear the CSR register and IRQ status register */ dma_write(OMAP2_DMA_CSR_CLEAR_MASK, CSR(lch));