From 664475cffb8cd2ee3b9602e60f07c244abb05d4a Mon Sep 17 00:00:00 2001 From: Dmitry Osipenko Date: Sun, 26 Apr 2020 22:08:35 +0300 Subject: [PATCH] dmaengine: tegra-apb: Ensure that clock is enabled during of DMA synchronization DMA synchronization hook checks whether interrupt is raised by testing corresponding bit in a hardware status register, and thus, clock should be enabled in this case, otherwise CPU may hang if synchronization is invoked while Runtime PM is in suspended state. This patch resumes the RPM during of the DMA synchronization process in order to avoid potential problems. It is a minor clean up of a previous commit, no real problem is fixed by this patch because currently RPM is always in a resumed state while DMA is synchronized, although this may change in the future. Fixes: 6697255f239f ("dmaengine: tegra-apb: Improve DMA synchronization") Signed-off-by: Dmitry Osipenko Link: https://lore.kernel.org/r/20200426190835.21950-1-digetx@gmail.com Signed-off-by: Vinod Koul --- drivers/dma/tegra20-apb-dma.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/drivers/dma/tegra20-apb-dma.c b/drivers/dma/tegra20-apb-dma.c index f6a2f42ffc51..b9f0d9636620 100644 --- a/drivers/dma/tegra20-apb-dma.c +++ b/drivers/dma/tegra20-apb-dma.c @@ -816,6 +816,13 @@ static bool tegra_dma_eoc_interrupt_deasserted(struct tegra_dma_channel *tdc) static void tegra_dma_synchronize(struct dma_chan *dc) { struct tegra_dma_channel *tdc = to_tegra_dma_chan(dc); + int err; + + err = pm_runtime_get_sync(tdc->tdma->dev); + if (err < 0) { + dev_err(tdc2dev(tdc), "Failed to synchronize DMA: %d\n", err); + return; + } /* * CPU, which handles interrupt, could be busy in @@ -825,6 +832,8 @@ static void tegra_dma_synchronize(struct dma_chan *dc) wait_event(tdc->wq, tegra_dma_eoc_interrupt_deasserted(tdc)); tasklet_kill(&tdc->tasklet); + + pm_runtime_put(tdc->tdma->dev); } static unsigned int tegra_dma_sg_bytes_xferred(struct tegra_dma_channel *tdc,