dmaengine: dw: Initialize channel before each transfer (99ba8b9b) · Commits · 戴 / test

In some cases DMA can be used only with a consumer which does runtime power management and on the platforms, that have DMA auto power gating logic (see comments in the drivers/acpi/acpi_lpss.c), may result in DMA losing its context. Simple mitigation of this issue is to initialize channel each time the consumer initiates a transfer. Fixes: ("dw_dmac: add support for Lynxpoint DMA controllers") Reported-by:

Tsuchiya Yuto <kitakar@gmail.com> Signed-off-by:

Andy Shevchenko <andriy.shevchenko@linux.intel.com> Acked-by:

Viresh Kumar <viresh.kumar@linaro.org> BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=206403 Link: https://lore.kernel.org/r/20200705115620.51929-1-andriy.shevchenko@linux.intel.com Signed-off-by:

Vinod Koul <vkoul@kernel.org>

drivers/dma/dw/core.c

+0 −12

Original line number	Diff line number	Diff line
		@@ -118,16 +118,11 @@ static void dwc_initialize(struct dw_dma_chan *dwc)
		{
		struct dw_dma *dw = to_dw_dma(dwc->chan.device);

		if (test_bit(DW_DMA_IS_INITIALIZED, &dwc->flags))
		return;

		dw->initialize_chan(dwc);

		/* Enable interrupts */
		channel_set_bit(dw, MASK.XFER, dwc->mask);
		channel_set_bit(dw, MASK.ERROR, dwc->mask);

		set_bit(DW_DMA_IS_INITIALIZED, &dwc->flags);
		}

		/----------------------------------------------------------------------/
		@@ -954,8 +949,6 @@ static void dwc_issue_pending(struct dma_chan *chan)

		void do_dw_dma_off(struct dw_dma *dw)
		{
		unsigned int i;

		dma_writel(dw, CFG, 0);

		channel_clear_bit(dw, MASK.XFER, dw->all_chan_mask);
		@@ -966,9 +959,6 @@ void do_dw_dma_off(struct dw_dma *dw)

		while (dma_readl(dw, CFG) & DW_CFG_DMA_EN)
		cpu_relax();

		for (i = 0; i < dw->dma.chancnt; i++)
		clear_bit(DW_DMA_IS_INITIALIZED, &dw->chan[i].flags);
		}

		void do_dw_dma_on(struct dw_dma *dw)
		@@ -1032,8 +1022,6 @@ static void dwc_free_chan_resources(struct dma_chan *chan)
		/* Clear custom channel configuration */
		memset(&dwc->dws, 0, sizeof(struct dw_dma_slave));

		clear_bit(DW_DMA_IS_INITIALIZED, &dwc->flags);

		/* Disable interrupts */
		channel_clear_bit(dw, MASK.XFER, dwc->mask);
		channel_clear_bit(dw, MASK.BLOCK, dwc->mask);

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