[PATCH v2 0/2] arm64: tegra: Enable DMA Support on Tegra194 QSPI

[PATCH v2 0/2] arm64: tegra: Enable DMA Support on Tegra194 QSPI

[Aaron Kling via B4 Relay]

The reason for this is to properly support the spi nor chip on the
Jetson Xavier NX module. Prior to this, it would time out on all
transfers and sometimes even trigger a cbb fault, locking up the entire
unit. With this, reading and writing to the flash memory works as
expected.

This also fixes the tegra210-quad spi driver to properly use the dma
memory space instead of the spi controllers. Without this, enabling dma
on the controllers results in mmu faults.

The driver change has only been tested on tegra210 / p3450 and tegra194
/ p3518 as that is the only available test platforms. Tegra234 and
Tegra241 should also be verified. I have p3766 for tegra234, but the
qspi flash memory is firewalled by mb1 on all publicly available
bootloaders, and no other spi devices are part of the devkit.

---
Changes in v2:
- Drop bindings patches
- Add patch to use dma memory space instead of the spi controllers when
  dma is enabled.
- Drop iommu properties from final patch
- Link to v1: https://lore.kernel.org/r/20260515-tegra194-qspi-iommu-v1-0-57dfb63cd3d6@gmail.com

---
Aaron Kling (2):
      spi: tegra210-quad: Allocate DMA memory for DMA engine
      arm64: tegra: Enable DMA Support on Tegra194 QSPI

 arch/arm64/boot/dts/nvidia/tegra194.dtsi |  4 ++++
 drivers/spi/spi-tegra210-quad.c          | 29 ++++++++++++++++++-----------
 2 files changed, 22 insertions(+), 11 deletions(-)
---
base-commit: c1ecb239fa3456529a32255359fc78b69eb9d847
change-id: 20260515-tegra194-qspi-iommu-e4e4644d5fdf

Best regards,
-- 
Aaron Kling <webgeek1234@gmail.com>

[PATCH v2 1/2] spi: tegra210-quad: Allocate DMA memory for DMA engine

[Aaron Kling via B4 Relay]

From: Aaron Kling <webgeek1234@gmail.com>

When the SPI controllers are running in DMA mode, it is the DMA engine
that performs the memory accesses rather than the SPI controller. Pass
the DMA engine's struct device pointer to the DMA API to make sure the
correct DMA operations are used.

Suggested-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Aaron Kling <webgeek1234@gmail.com>
---
 drivers/spi/spi-tegra210-quad.c | 29 ++++++++++++++++++-----------
 1 file changed, 18 insertions(+), 11 deletions(-)

diff --git a/drivers/spi/spi-tegra210-quad.c b/drivers/spi/spi-tegra210-quad.c
index db28dd556484b2..588a929a97850a 100644
--- a/drivers/spi/spi-tegra210-quad.c
+++ b/drivers/spi/spi-tegra210-quad.c
@@ -226,11 +226,13 @@ struct tegra_qspi {
 	struct completion			xfer_completion;
 	struct spi_transfer			*curr_xfer;
 
+	struct device				*rx_dma_dev;
 	struct dma_chan				*rx_dma_chan;
 	u32					*rx_dma_buf;
 	dma_addr_t				rx_dma_phys;
 	struct dma_async_tx_descriptor		*rx_dma_desc;
 
+	struct device				*tx_dma_dev;
 	struct dma_chan				*tx_dma_chan;
 	u32					*tx_dma_buf;
 	dma_addr_t				tx_dma_phys;
@@ -574,15 +576,15 @@ static int tegra_qspi_dma_map_xfer(struct tegra_qspi *tqspi, struct spi_transfer
 	len = DIV_ROUND_UP(tqspi->curr_dma_words * tqspi->bytes_per_word, 4) * 4;
 
 	if (t->tx_buf) {
-		t->tx_dma = dma_map_single(tqspi->dev, (void *)tx_buf, len, DMA_TO_DEVICE);
-		if (dma_mapping_error(tqspi->dev, t->tx_dma))
+		t->tx_dma = dma_map_single(tqspi->tx_dma_dev, (void *)tx_buf, len, DMA_TO_DEVICE);
+		if (dma_mapping_error(tqspi->tx_dma_dev, t->tx_dma))
 			return -ENOMEM;
 	}
 
 	if (t->rx_buf) {
-		t->rx_dma = dma_map_single(tqspi->dev, (void *)rx_buf, len, DMA_FROM_DEVICE);
-		if (dma_mapping_error(tqspi->dev, t->rx_dma)) {
-			dma_unmap_single(tqspi->dev, t->tx_dma, len, DMA_TO_DEVICE);
+		t->rx_dma = dma_map_single(tqspi->rx_dma_dev, (void *)rx_buf, len, DMA_FROM_DEVICE);
+		if (dma_mapping_error(tqspi->rx_dma_dev, t->rx_dma)) {
+			dma_unmap_single(tqspi->tx_dma_dev, t->tx_dma, len, DMA_TO_DEVICE);
 			return -ENOMEM;
 		}
 	}
@@ -597,9 +599,9 @@ static void tegra_qspi_dma_unmap_xfer(struct tegra_qspi *tqspi, struct spi_trans
 	len = DIV_ROUND_UP(tqspi->curr_dma_words * tqspi->bytes_per_word, 4) * 4;
 
 	if (t->tx_buf)
-		dma_unmap_single(tqspi->dev, t->tx_dma, len, DMA_TO_DEVICE);
+		dma_unmap_single(tqspi->tx_dma_dev, t->tx_dma, len, DMA_TO_DEVICE);
 	if (t->rx_buf)
-		dma_unmap_single(tqspi->dev, t->rx_dma, len, DMA_FROM_DEVICE);
+		dma_unmap_single(tqspi->rx_dma_dev, t->rx_dma, len, DMA_FROM_DEVICE);
 }
 
 static int tegra_qspi_start_dma_based_transfer(struct tegra_qspi *tqspi, struct spi_transfer *t)
@@ -745,7 +747,7 @@ static int tegra_qspi_start_cpu_based_transfer(struct tegra_qspi *qspi, struct s
 static void tegra_qspi_deinit_dma(struct tegra_qspi *tqspi)
 {
 	if (tqspi->tx_dma_buf) {
-		dma_free_coherent(tqspi->dev, tqspi->dma_buf_size,
+		dma_free_coherent(tqspi->tx_dma_dev, tqspi->dma_buf_size,
 				  tqspi->tx_dma_buf, tqspi->tx_dma_phys);
 		tqspi->tx_dma_buf = NULL;
 	}
@@ -756,7 +758,7 @@ static void tegra_qspi_deinit_dma(struct tegra_qspi *tqspi)
 	}
 
 	if (tqspi->rx_dma_buf) {
-		dma_free_coherent(tqspi->dev, tqspi->dma_buf_size,
+		dma_free_coherent(tqspi->rx_dma_dev, tqspi->dma_buf_size,
 				  tqspi->rx_dma_buf, tqspi->rx_dma_phys);
 		tqspi->rx_dma_buf = NULL;
 	}
@@ -782,6 +784,7 @@ static int tegra_qspi_init_dma(struct tegra_qspi *tqspi)
 		}
 
 		tqspi->rx_dma_chan = dma_chan;
+		tqspi->rx_dma_dev = dmaengine_get_dma_device(tqspi->rx_dma_chan);
 
 		dma_chan = dma_request_chan(tqspi->dev, "tx");
 		if (IS_ERR(dma_chan)) {
@@ -790,15 +793,19 @@ static int tegra_qspi_init_dma(struct tegra_qspi *tqspi)
 		}
 
 		tqspi->tx_dma_chan = dma_chan;
+		tqspi->tx_dma_dev = dmaengine_get_dma_device(tqspi->tx_dma_chan);
 	} else {
 		if (!device_iommu_mapped(tqspi->dev)) {
 			dev_warn(tqspi->dev,
 				 "IOMMU not enabled in device-tree, falling back to PIO mode\n");
 			return 0;
 		}
+
+		tqspi->rx_dma_dev = tqspi->dev;
+		tqspi->tx_dma_dev = tqspi->dev;
 	}
 
-	dma_buf = dma_alloc_coherent(tqspi->dev, tqspi->dma_buf_size, &dma_phys, GFP_KERNEL);
+	dma_buf = dma_alloc_coherent(tqspi->rx_dma_dev, tqspi->dma_buf_size, &dma_phys, GFP_KERNEL);
 	if (!dma_buf) {
 		err = -ENOMEM;
 		goto err_out;
@@ -807,7 +814,7 @@ static int tegra_qspi_init_dma(struct tegra_qspi *tqspi)
 	tqspi->rx_dma_buf = dma_buf;
 	tqspi->rx_dma_phys = dma_phys;
 
-	dma_buf = dma_alloc_coherent(tqspi->dev, tqspi->dma_buf_size, &dma_phys, GFP_KERNEL);
+	dma_buf = dma_alloc_coherent(tqspi->tx_dma_dev, tqspi->dma_buf_size, &dma_phys, GFP_KERNEL);
 	if (!dma_buf) {
 		err = -ENOMEM;
 		goto err_out;

-- 
2.53.0

[PATCH v2 2/2] arm64: tegra: Enable DMA Support on Tegra194 QSPI

[Aaron Kling via B4 Relay]

From: Aaron Kling <webgeek1234@gmail.com>

Without dma enabled pio mode is used and flash storage such as the one
on the p3668 module times out and cannot complete any transfers. In some
cases, these timeouts cause hangs and cbb faults.

Signed-off-by: Aaron Kling <webgeek1234@gmail.com>
---
 arch/arm64/boot/dts/nvidia/tegra194.dtsi | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/arm64/boot/dts/nvidia/tegra194.dtsi b/arch/arm64/boot/dts/nvidia/tegra194.dtsi
index 1d659454a6f9fe..e2ddbc6715d5e8 100644
--- a/arch/arm64/boot/dts/nvidia/tegra194.dtsi
+++ b/arch/arm64/boot/dts/nvidia/tegra194.dtsi
@@ -923,6 +923,8 @@ spi@3270000 {
 				 <&bpmp TEGRA194_CLK_QSPI0_PM>;
 			clock-names = "qspi", "qspi_out";
 			resets = <&bpmp TEGRA194_RESET_QSPI0>;
+			dmas = <&gpcdma 5>, <&gpcdma 5>;
+			dma-names = "rx", "tx";
 			status = "disabled";
 		};
 
@@ -1013,6 +1015,8 @@ spi@3300000 {
 				 <&bpmp TEGRA194_CLK_QSPI1_PM>;
 			clock-names = "qspi", "qspi_out";
 			resets = <&bpmp TEGRA194_RESET_QSPI1>;
+			dmas = <&gpcdma 6>, <&gpcdma 6>;
+			dma-names = "rx", "tx";
 			status = "disabled";
 		};
 

-- 
2.53.0

Re: [PATCH v2 2/2] arm64: tegra: Enable DMA Support on Tegra194 QSPI

[Aaron Kling]

On Mon, May 25, 2026 at 1:47 AM Aaron Kling via B4 Relay
<devnull+webgeek1234.gmail.com@kernel.org> wrote:
>
> From: Aaron Kling <webgeek1234@gmail.com>
>
> Without dma enabled pio mode is used and flash storage such as the one
> on the p3668 module times out and cannot complete any transfers. In some
> cases, these timeouts cause hangs and cbb faults.
>
> Signed-off-by: Aaron Kling <webgeek1234@gmail.com>
> ---
>  arch/arm64/boot/dts/nvidia/tegra194.dtsi | 4 ++++
>  1 file changed, 4 insertions(+)
>
> diff --git a/arch/arm64/boot/dts/nvidia/tegra194.dtsi b/arch/arm64/boot/dts/nvidia/tegra194.dtsi
> index 1d659454a6f9fe..e2ddbc6715d5e8 100644
> --- a/arch/arm64/boot/dts/nvidia/tegra194.dtsi
> +++ b/arch/arm64/boot/dts/nvidia/tegra194.dtsi
> @@ -923,6 +923,8 @@ spi@3270000 {
>                                  <&bpmp TEGRA194_CLK_QSPI0_PM>;
>                         clock-names = "qspi", "qspi_out";
>                         resets = <&bpmp TEGRA194_RESET_QSPI0>;
> +                       dmas = <&gpcdma 5>, <&gpcdma 5>;
> +                       dma-names = "rx", "tx";
>                         status = "disabled";
>                 };
>
> @@ -1013,6 +1015,8 @@ spi@3300000 {
>                                  <&bpmp TEGRA194_CLK_QSPI1_PM>;
>                         clock-names = "qspi", "qspi_out";
>                         resets = <&bpmp TEGRA194_RESET_QSPI1>;
> +                       dmas = <&gpcdma 6>, <&gpcdma 6>;
> +                       dma-names = "rx", "tx";
>                         status = "disabled";
>                 };
>
>
> --
> 2.53.0
>
>

Thierry,

The driver change was picked up some time ago and is part of 7.2. Can
this be picked up for 7.3?

Aaron

Re: [PATCH v2 2/2] arm64: tegra: Enable DMA Support on Tegra194 QSPI

[Thierry Reding]

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On Mon, May 25, 2026 at 01:47:45AM -0500, Aaron Kling via B4 Relay wrote:
> From: Aaron Kling <webgeek1234@gmail.com>
> 
> Without dma enabled pio mode is used and flash storage such as the one
> on the p3668 module times out and cannot complete any transfers. In some
> cases, these timeouts cause hangs and cbb faults.
> 
> Signed-off-by: Aaron Kling <webgeek1234@gmail.com>
> ---
>  arch/arm64/boot/dts/nvidia/tegra194.dtsi | 4 ++++
>  1 file changed, 4 insertions(+)

Applied now, thanks.

Thierry

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Re: (subset) [PATCH v2 0/2] arm64: tegra: Enable DMA Support on Tegra194 QSPI

[Mark Brown]

On Mon, 25 May 2026 01:47:43 -0500, Aaron Kling wrote:
> arm64: tegra: Enable DMA Support on Tegra194 QSPI
> 
> The reason for this is to properly support the spi nor chip on the
> Jetson Xavier NX module. Prior to this, it would time out on all
> transfers and sometimes even trigger a cbb fault, locking up the entire
> unit. With this, reading and writing to the flash memory works as
> expected.
> 
> [...]

Applied to

   https://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi.git for-7.2

Thanks!

[1/2] spi: tegra210-quad: Allocate DMA memory for DMA engine
      https://git.kernel.org/broonie/spi/c/f469138a77ac

All being well this means that it will be integrated into the linux-next
tree (usually sometime in the next 24 hours) and sent to Linus during
the next merge window (or sooner if it is a bug fix), however if
problems are discovered then the patch may be dropped or reverted.

You may get further e-mails resulting from automated or manual testing
and review of the tree, please engage with people reporting problems and
send followup patches addressing any issues that are reported if needed.

If any updates are required or you are submitting further changes they
should be sent as incremental updates against current git, existing
patches will not be replaced.

Please add any relevant lists and maintainers to the CCs when replying
to this mail.

Thanks,
Mark