On Thu, Jan 5, 2012 at 2:07 PM, Stephen Warren <[email protected]> wrote: > Olof Johansson wrote at Wednesday, January 04, 2012 10:49 PM: >> Tegra2 hangs if APB registers are accessed from the cpu during an >> apb dma operation. The workaround is to use apb dma to read/write the >> registers instead. > ... >> diff --git a/arch/arm/mach-tegra/apbio.c b/arch/arm/mach-tegra/apbio.c > ... >> +u32 tegra_apb_readl(unsigned long offset) > ... >> + INIT_COMPLETION(tegra_apb_wait); >> + >> + tegra_dma_enqueue_req(tegra_apb_dma, &req); >> + >> + ret = wait_for_completion_timeout(&tegra_apb_wait, >> + msecs_to_jiffies(50)); >> + >> + if (WARN(ret == 0, "apb read dma timed out")) { >> + *(u32 *)tegra_apb_bb = 0; >> + tegra_dma_dequeue_req(tegra_apb_dma, &req); > > I think you need to swap those last two lines to make absolutely sure > that the timeout handling doesn't race with an actual DMA completion.
Ah, of course. Fixing that without reposting. > Acked-by: Stephen Warren <[email protected]> Thanks! -Olof -- To unsubscribe from this list: send the line "unsubscribe linux-tegra" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
