From 409ffc4d990c157f876f105d06e11c1f21444cb7 Mon Sep 17 00:00:00 2001 From: Amelie Delaunay Date: Wed, 29 Jan 2020 16:36:27 +0100 Subject: [PATCH] dmaengine: stm32-dma: fix sleeping function called from invalid context This patch fixes BUG: sleeping function called from invalid context in stm32_dma_disable_chan function. The goal of this function is to force channel disable if it has not been disabled by hardware. This consists in clearing STM32_DMA_SCR_EN bit and read it as 0 to ensure the channel is well disabled and the last transfer is over. In previous implementation, the waiting loop was based on a do...while (1) with a call to cond_resched to give the scheduler a chance to run a higher priority process. But in some conditions, stm32_dma_disable_chan can be called while preemption is disabled, on a stm32_dma_stop call for example. So cond_resched must not be used. To avoid this, use readl_relaxed_poll_timeout_atomic to poll STM32_DMA_SCR_EN bit cleared. Signed-off-by: Amelie Delaunay Link: https://lore.kernel.org/r/20200129153628.29329-8-amelie.delaunay@st.com Signed-off-by: Vinod Koul --- drivers/dma/stm32-dma.c | 25 ++++++++----------------- 1 file changed, 8 insertions(+), 17 deletions(-) diff --git a/drivers/dma/stm32-dma.c b/drivers/dma/stm32-dma.c index 01a2374ae03a..b585e11c2168 100644 --- a/drivers/dma/stm32-dma.c +++ b/drivers/dma/stm32-dma.c @@ -15,6 +15,7 @@ #include #include #include +#include #include #include #include @@ -421,29 +422,19 @@ static void stm32_dma_irq_clear(struct stm32_dma_chan *chan, u32 flags) static int stm32_dma_disable_chan(struct stm32_dma_chan *chan) { struct stm32_dma_device *dmadev = stm32_dma_get_dev(chan); - unsigned long timeout = jiffies + msecs_to_jiffies(5000); - u32 dma_scr, id; + u32 dma_scr, id, reg; id = chan->id; - dma_scr = stm32_dma_read(dmadev, STM32_DMA_SCR(id)); + reg = STM32_DMA_SCR(id); + dma_scr = stm32_dma_read(dmadev, reg); if (dma_scr & STM32_DMA_SCR_EN) { dma_scr &= ~STM32_DMA_SCR_EN; - stm32_dma_write(dmadev, STM32_DMA_SCR(id), dma_scr); + stm32_dma_write(dmadev, reg, dma_scr); - do { - dma_scr = stm32_dma_read(dmadev, STM32_DMA_SCR(id)); - dma_scr &= STM32_DMA_SCR_EN; - if (!dma_scr) - break; - - if (time_after_eq(jiffies, timeout)) { - dev_err(chan2dev(chan), "%s: timeout!\n", - __func__); - return -EBUSY; - } - cond_resched(); - } while (1); + return readl_relaxed_poll_timeout_atomic(dmadev->base + reg, + dma_scr, !(dma_scr & STM32_DMA_SCR_EN), + 10, 1000000); } return 0;