From a6ecb122a7a0d8ad93890cd3a1e5bd5f44de614a Mon Sep 17 00:00:00 2001 From: Andy Shevchenko Date: Sun, 5 Jul 2020 14:56:20 +0300 Subject: [PATCH] dmaengine: dw: Initialize channel before each transfer 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: cfdf5b6cc598 ("dw_dmac: add support for Lynxpoint DMA controllers") Reported-by: Tsuchiya Yuto Signed-off-by: Andy Shevchenko Acked-by: Viresh Kumar 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 (cherry picked from commit 99ba8b9b0d9780e9937eb1d488d120e9e5c2533d) [Reason for cherry-picking this commit: This commit fixes touch input when using DMA mode on Surface 3's touchscreen. Note: this commit was not backported to v4.19 by upstream. For now, backport this patch ourselves.] [ Conflicts: drivers/dma/dw/core.c Resolved conflict by accepting current change then removed DW_DMA_IS_INITIALIZED lines] Signed-off-by: Tsuchiya Yuto Patchset: surface3-touchscreen-dma-fix --- drivers/dma/dw/core.c | 12 ------------ 1 file changed, 12 deletions(-) diff --git a/drivers/dma/dw/core.c b/drivers/dma/dw/core.c index 055d83b6cb68..acf64302a2b2 100644 --- a/drivers/dma/dw/core.c +++ b/drivers/dma/dw/core.c @@ -180,9 +180,6 @@ 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; - if (dw->pdata->is_idma32) dwc_initialize_chan_idma32(dwc); else @@ -191,8 +188,6 @@ static void dwc_initialize(struct dw_dma_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); } /*----------------------------------------------------------------------*/ @@ -1091,8 +1086,6 @@ static void idma32_fifo_partition(struct dw_dma *dw) static void 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); @@ -1103,9 +1096,6 @@ static void 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); } static void dw_dma_on(struct dw_dma *dw) @@ -1170,8 +1160,6 @@ 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); -- 2.33.0