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>
diff --git a/drivers/dma/sh/rcar-dmac.c b/drivers/dma/sh/rcar-dmac.c
index 711da01..a18d16c 100644
--- a/drivers/dma/sh/rcar-dmac.c
+++ b/drivers/dma/sh/rcar-dmac.c
@@ -1593,6 +1593,7 @@
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 @@
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 @@
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;
}