Use 'iommu-map', when provided, to get the stream ID to be programmed
for each channel. Iterate over the channels registered and configure
each channel device separately using of_dma_configure_id() to allow
it to use a separate IOMMU domain for the transfer. However, do this
in a second loop since the first loop populates the DMA device channels
list and async_device_register() registers the channels. Both are
prerequisites for using the channel device in the next loop.
Channels will continue to use the same global stream ID if the
'iommu-map' property is not present in the device tree.
Signed-off-by: Akhil R <akhilrajeev@nvidia.com>
---
drivers/dma/tegra186-gpc-dma.c | 57 ++++++++++++++++++++++++++++------
1 file changed, 48 insertions(+), 9 deletions(-)
diff --git a/drivers/dma/tegra186-gpc-dma.c b/drivers/dma/tegra186-gpc-dma.c
index 9bea2ffb3b9e..64743d852dda 100644
--- a/drivers/dma/tegra186-gpc-dma.c
+++ b/drivers/dma/tegra186-gpc-dma.c
@@ -15,6 +15,7 @@
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_dma.h>
+#include <linux/of_device.h>
#include <linux/platform_device.h>
#include <linux/reset.h>
#include <linux/slab.h>
@@ -1380,9 +1381,13 @@ static int tegra_dma_program_sid(struct tegra_dma_channel *tdc, int stream_id)
static int tegra_dma_probe(struct platform_device *pdev)
{
const struct tegra_dma_chip_data *cdata = NULL;
+ struct tegra_dma_channel *tdc;
+ struct tegra_dma *tdma;
+ struct dma_chan *chan;
+ struct device *chdev;
+ bool use_iommu_map = false;
unsigned int i;
u32 stream_id;
- struct tegra_dma *tdma;
int ret;
cdata = of_device_get_match_data(&pdev->dev);
@@ -1410,9 +1415,12 @@ static int tegra_dma_probe(struct platform_device *pdev)
tdma->dma_dev.dev = &pdev->dev;
- if (!tegra_dev_iommu_get_stream_id(&pdev->dev, &stream_id)) {
- dev_err(&pdev->dev, "Missing iommu stream-id\n");
- return -EINVAL;
+ use_iommu_map = of_property_present(pdev->dev.of_node, "iommu-map");
+ if (!use_iommu_map) {
+ if (!tegra_dev_iommu_get_stream_id(&pdev->dev, &stream_id)) {
+ dev_err(&pdev->dev, "Missing iommu stream-id\n");
+ return -EINVAL;
+ }
}
ret = device_property_read_u32(&pdev->dev, "dma-channel-mask",
@@ -1424,9 +1432,10 @@ static int tegra_dma_probe(struct platform_device *pdev)
tdma->chan_mask = TEGRA_GPCDMA_DEFAULT_CHANNEL_MASK;
}
+ /* Initialize vchan for each channel and populate the channels list */
INIT_LIST_HEAD(&tdma->dma_dev.channels);
for (i = 0; i < cdata->nr_channels; i++) {
- struct tegra_dma_channel *tdc = &tdma->channels[i];
+ tdc = &tdma->channels[i];
/* Check for channel mask */
if (!(tdma->chan_mask & BIT(i)))
@@ -1446,10 +1455,6 @@ static int tegra_dma_probe(struct platform_device *pdev)
vchan_init(&tdc->vc, &tdma->dma_dev);
tdc->vc.desc_free = tegra_dma_desc_free;
-
- /* program stream-id for this channel */
- tegra_dma_program_sid(tdc, stream_id);
- tdc->stream_id = stream_id;
}
dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(cdata->addr_bits));
@@ -1483,6 +1488,7 @@ static int tegra_dma_probe(struct platform_device *pdev)
tdma->dma_dev.device_synchronize = tegra_dma_chan_synchronize;
tdma->dma_dev.residue_granularity = DMA_RESIDUE_GRANULARITY_BURST;
+ /* Register the DMA device and the channels */
ret = dmaenginem_async_device_register(&tdma->dma_dev);
if (ret < 0) {
dev_err_probe(&pdev->dev, ret,
@@ -1490,6 +1496,39 @@ static int tegra_dma_probe(struct platform_device *pdev)
return ret;
}
+ /*
+ * Configure stream ID for each channel from the channels registered
+ * above. This is done in a separate iteration to ensure that only
+ * the channels available and registered for the DMA device are used.
+ */
+ list_for_each_entry(chan, &tdma->dma_dev.channels, device_node) {
+ chdev = &chan->dev->device;
+ tdc = to_tegra_dma_chan(chan);
+
+ if (use_iommu_map) {
+ chdev->bus = pdev->dev.bus;
+ dma_coerce_mask_and_coherent(chdev, DMA_BIT_MASK(cdata->addr_bits));
+
+ ret = of_dma_configure_id(chdev, pdev->dev.of_node,
+ true, &tdc->id);
+ if (ret)
+ return dev_err_probe(chdev, ret,
+ "Failed to configure IOMMU for channel %d", tdc->id);
+
+ if (!tegra_dev_iommu_get_stream_id(chdev, &stream_id)) {
+ dev_err(chdev, "Failed to get stream ID for channel %d\n",
+ tdc->id);
+ return -EINVAL;
+ }
+
+ chan->dev->chan_dma_dev = true;
+ }
+
+ /* program stream-id for this channel */
+ tegra_dma_program_sid(tdc, stream_id);
+ tdc->stream_id = stream_id;
+ }
+
ret = devm_of_dma_controller_register(&pdev->dev, pdev->dev.of_node,
tegra_dma_of_xlate, tdma);
if (ret < 0) {
--
2.50.1On Mon, Mar 30, 2026 at 08:14:54PM +0530, Akhil R wrote:
> Use 'iommu-map', when provided, to get the stream ID to be programmed
> for each channel. Iterate over the channels registered and configure
> each channel device separately using of_dma_configure_id() to allow
> it to use a separate IOMMU domain for the transfer. However, do this
> in a second loop since the first loop populates the DMA device channels
> list and async_device_register() registers the channels. Both are
> prerequisites for using the channel device in the next loop.
>
> Channels will continue to use the same global stream ID if the
> 'iommu-map' property is not present in the device tree.
>
> Signed-off-by: Akhil R <akhilrajeev@nvidia.com>
> ---
...
>
> + /*
> + * Configure stream ID for each channel from the channels registered
> + * above. This is done in a separate iteration to ensure that only
> + * the channels available and registered for the DMA device are used.
> + */
> + list_for_each_entry(chan, &tdma->dma_dev.channels, device_node) {
> + chdev = &chan->dev->device;
> + tdc = to_tegra_dma_chan(chan);
> +
> + if (use_iommu_map) {
> + chdev->bus = pdev->dev.bus;
> + dma_coerce_mask_and_coherent(chdev, DMA_BIT_MASK(cdata->addr_bits));
> +
> + ret = of_dma_configure_id(chdev, pdev->dev.of_node,
> + true, &tdc->id);
> + if (ret)
> + return dev_err_probe(chdev, ret,
> + "Failed to configure IOMMU for channel %d", tdc->id);
> +
> + if (!tegra_dev_iommu_get_stream_id(chdev, &stream_id)) {
> + dev_err(chdev, "Failed to get stream ID for channel %d\n",
> + tdc->id);
> + return -EINVAL;
Can you check similar problem before post patch, here also can use
return dev_err_probe()
Frank
> + }
> +
> + chan->dev->chan_dma_dev = true;
> + }
> +
> + /* program stream-id for this channel */
> + tegra_dma_program_sid(tdc, stream_id);
> + tdc->stream_id = stream_id;
> + }
> +
> ret = devm_of_dma_controller_register(&pdev->dev, pdev->dev.of_node,
> tegra_dma_of_xlate, tdma);
> if (ret < 0) {
> --
> 2.50.1
>
On Mon, 30 Mar 2026 12:47:24 -0400, Frank Li wrote:
> On Mon, Mar 30, 2026 at 08:14:54PM +0530, Akhil R wrote:
>> Use 'iommu-map', when provided, to get the stream ID to be programmed
>> for each channel. Iterate over the channels registered and configure
>> each channel device separately using of_dma_configure_id() to allow
>> it to use a separate IOMMU domain for the transfer. However, do this
>> in a second loop since the first loop populates the DMA device channels
>> list and async_device_register() registers the channels. Both are
>> prerequisites for using the channel device in the next loop.
>>
>> Channels will continue to use the same global stream ID if the
>> 'iommu-map' property is not present in the device tree.
>>
>> Signed-off-by: Akhil R <akhilrajeev@nvidia.com>
>> ---
> ...
>>
>> + /*
>> + * Configure stream ID for each channel from the channels registered
>> + * above. This is done in a separate iteration to ensure that only
>> + * the channels available and registered for the DMA device are used.
>> + */
>> + list_for_each_entry(chan, &tdma->dma_dev.channels, device_node) {
>> + chdev = &chan->dev->device;
>> + tdc = to_tegra_dma_chan(chan);
>> +
>> + if (use_iommu_map) {
>> + chdev->bus = pdev->dev.bus;
>> + dma_coerce_mask_and_coherent(chdev, DMA_BIT_MASK(cdata->addr_bits));
>> +
>> + ret = of_dma_configure_id(chdev, pdev->dev.of_node,
>> + true, &tdc->id);
>> + if (ret)
>> + return dev_err_probe(chdev, ret,
>> + "Failed to configure IOMMU for channel %d", tdc->id);
>> +
>> + if (!tegra_dev_iommu_get_stream_id(chdev, &stream_id)) {
>> + dev_err(chdev, "Failed to get stream ID for channel %d\n",
>> + tdc->id);
>> + return -EINVAL;
>
> Can you check similar problem before post patch, here also can use
> return dev_err_probe()
I did notice that, but I thought dev_err_probe is to handle -EPROBE_DEFER
and we do not use it when we return a fixed value. It returns -EINVAL here
directly.
Best Regards,
Akhil
On Mon, Mar 30, 2026 at 11:32:40PM +0530, Akhil R wrote:
> On Mon, 30 Mar 2026 12:47:24 -0400, Frank Li wrote:
> > On Mon, Mar 30, 2026 at 08:14:54PM +0530, Akhil R wrote:
> >> Use 'iommu-map', when provided, to get the stream ID to be programmed
> >> for each channel. Iterate over the channels registered and configure
> >> each channel device separately using of_dma_configure_id() to allow
> >> it to use a separate IOMMU domain for the transfer. However, do this
> >> in a second loop since the first loop populates the DMA device channels
> >> list and async_device_register() registers the channels. Both are
> >> prerequisites for using the channel device in the next loop.
> >>
> >> Channels will continue to use the same global stream ID if the
> >> 'iommu-map' property is not present in the device tree.
> >>
> >> Signed-off-by: Akhil R <akhilrajeev@nvidia.com>
> >> ---
> > ...
> >>
> >> + /*
> >> + * Configure stream ID for each channel from the channels registered
> >> + * above. This is done in a separate iteration to ensure that only
> >> + * the channels available and registered for the DMA device are used.
> >> + */
> >> + list_for_each_entry(chan, &tdma->dma_dev.channels, device_node) {
> >> + chdev = &chan->dev->device;
> >> + tdc = to_tegra_dma_chan(chan);
> >> +
> >> + if (use_iommu_map) {
> >> + chdev->bus = pdev->dev.bus;
> >> + dma_coerce_mask_and_coherent(chdev, DMA_BIT_MASK(cdata->addr_bits));
> >> +
> >> + ret = of_dma_configure_id(chdev, pdev->dev.of_node,
> >> + true, &tdc->id);
> >> + if (ret)
> >> + return dev_err_probe(chdev, ret,
> >> + "Failed to configure IOMMU for channel %d", tdc->id);
> >> +
> >> + if (!tegra_dev_iommu_get_stream_id(chdev, &stream_id)) {
> >> + dev_err(chdev, "Failed to get stream ID for channel %d\n",
> >> + tdc->id);
> >> + return -EINVAL;
> >
> > Can you check similar problem before post patch, here also can use
> > return dev_err_probe()
>
> I did notice that, but I thought dev_err_probe is to handle -EPROBE_DEFER
> and we do not use it when we return a fixed value. It returns -EINVAL here
> directly.
even that, still can use return dev_err_probe(chddev, -EINVAL, ...) to
short your code.
Frank
>
> Best Regards,
> Akhil
On Mon, 30 Mar 2026 14:15:43 -0400, Frank Li wrote:
> On Mon, Mar 30, 2026 at 11:32:40PM +0530, Akhil R wrote:
>> On Mon, 30 Mar 2026 12:47:24 -0400, Frank Li wrote:
>> > On Mon, Mar 30, 2026 at 08:14:54PM +0530, Akhil R wrote:
>> >> Use 'iommu-map', when provided, to get the stream ID to be programmed
>> >> for each channel. Iterate over the channels registered and configure
>> >> each channel device separately using of_dma_configure_id() to allow
>> >> it to use a separate IOMMU domain for the transfer. However, do this
>> >> in a second loop since the first loop populates the DMA device channels
>> >> list and async_device_register() registers the channels. Both are
>> >> prerequisites for using the channel device in the next loop.
>> >>
>> >> Channels will continue to use the same global stream ID if the
>> >> 'iommu-map' property is not present in the device tree.
>> >>
>> >> Signed-off-by: Akhil R <akhilrajeev@nvidia.com>
>> >> ---
>> > ...
>> >>
>> >> + /*
>> >> + * Configure stream ID for each channel from the channels registered
>> >> + * above. This is done in a separate iteration to ensure that only
>> >> + * the channels available and registered for the DMA device are used.
>> >> + */
>> >> + list_for_each_entry(chan, &tdma->dma_dev.channels, device_node) {
>> >> + chdev = &chan->dev->device;
>> >> + tdc = to_tegra_dma_chan(chan);
>> >> +
>> >> + if (use_iommu_map) {
>> >> + chdev->bus = pdev->dev.bus;
>> >> + dma_coerce_mask_and_coherent(chdev, DMA_BIT_MASK(cdata->addr_bits));
>> >> +
>> >> + ret = of_dma_configure_id(chdev, pdev->dev.of_node,
>> >> + true, &tdc->id);
>> >> + if (ret)
>> >> + return dev_err_probe(chdev, ret,
>> >> + "Failed to configure IOMMU for channel %d", tdc->id);
>> >> +
>> >> + if (!tegra_dev_iommu_get_stream_id(chdev, &stream_id)) {
>> >> + dev_err(chdev, "Failed to get stream ID for channel %d\n",
>> >> + tdc->id);
>> >> + return -EINVAL;
>> >
>> > Can you check similar problem before post patch, here also can use
>> > return dev_err_probe()
>>
>> I did notice that, but I thought dev_err_probe is to handle -EPROBE_DEFER
>> and we do not use it when we return a fixed value. It returns -EINVAL here
>> directly.
>
> even that, still can use return dev_err_probe(chddev, -EINVAL, ...) to
> short your code.
I just saw in the dev_err_probe() description that it is not limited to
-EPROBE_DEFER. Thanks for pointing. I will update the patch.
Best Regards,
Akhil
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