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authorLaurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>2015-01-27 20:04:10 +0300
committerVinod Koul <vinod.koul@intel.com>2015-02-16 07:03:35 +0300
commitbe6893e1958035cbeff281b833777c5cd3fb36ad (patch)
tree093195bbad635531be5814a8d3403aef0d557865 /drivers
parent3f46306127bb7d8a69078ff9ef8a5827677c2159 (diff)
downloadlinux-be6893e1958035cbeff281b833777c5cd3fb36ad.tar.xz
dmaengine: rcar-dmac: Disable channel 0 when using IOMMU
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>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/dma/sh/rcar-dmac.c17
1 files changed, 16 insertions, 1 deletions
diff --git a/drivers/dma/sh/rcar-dmac.c b/drivers/dma/sh/rcar-dmac.c
index 711da01a200b..a18d16cc4795 100644
--- a/drivers/dma/sh/rcar-dmac.c
+++ b/drivers/dma/sh/rcar-dmac.c
@@ -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;
}