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dmaengine: rcar-dmac: Disable channel 0 when using IOMMU

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A still unconfirmed hardware bug prevents the IPMMU microTLB 0 to be
flushed correctly, resulting in memory corruption. DMAC 0 channel 0 is
connected to microTLB 0 on currently supported platforms, so we can't
use it with the IPMMU. As the IOMMU API operates at the device level we
can't disable it selectively, so ignore channel 0 for now if the device
is part of an IOMMU group.

Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Acked-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
This commit is contained in:
Laurent Pinchart 2015-01-27 19:04:10 +02:00 committed by Vinod Koul
parent 3f46306127
commit be6893e195
1 changed files with 16 additions and 1 deletions
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17
drivers/dma/sh/rcar-dmac.c
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@ -1593,6 +1593,7 @@ static int rcar_dmac_probe(struct platform_device *pdev)
DMA_SLAVE_BUSWIDTH_2_BYTES | DMA_SLAVE_BUSWIDTH_4_BYTES |
DMA_SLAVE_BUSWIDTH_8_BYTES | DMA_SLAVE_BUSWIDTH_16_BYTES |
DMA_SLAVE_BUSWIDTH_32_BYTES | DMA_SLAVE_BUSWIDTH_64_BYTES;
unsigned int channels_offset = 0;
struct dma_device *engine;
struct rcar_dmac *dmac;
struct resource *mem;
@ -1612,6 +1613,19 @@ static int rcar_dmac_probe(struct platform_device *pdev)
if (ret < 0)
return ret;
/*
* A still unconfirmed hardware bug prevents the IPMMU microTLB 0 to be
* flushed correctly, resulting in memory corruption. DMAC 0 channel 0
* is connected to microTLB 0 on currently supported platforms, so we
* can't use it with the IPMMU. As the IOMMU API operates at the device
* level we can't disable it selectively, so ignore channel 0 for now if
* the device is part of an IOMMU group.
*/
if (pdev->dev.iommu_group) {
dmac->n_channels--;
channels_offset = 1;
}
dmac->channels = devm_kcalloc(&pdev->dev, dmac->n_channels,
sizeof(*dmac->channels), GFP_KERNEL);
if (!dmac->channels)
@ -1662,7 +1676,8 @@ static int rcar_dmac_probe(struct platform_device *pdev)
INIT_LIST_HEAD(&dmac->engine.channels);
for (i = 0; i < dmac->n_channels; ++i) {
ret = rcar_dmac_chan_probe(dmac, &dmac->channels[i], i);
ret = rcar_dmac_chan_probe(dmac, &dmac->channels[i],
i + channels_offset);
if (ret < 0)
goto error;
}