Re: [PATCH 0/3] arm64: tegra: Add iommu and dma properties for Tegra194 QSPI

[Jon Hunter]

On 15/05/2026 21:35, Aaron Kling via B4 Relay wrote:
> 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.

What kernel's do you see this on? With the latest mainline/-next I do 
see ...

 tegra-qspi 3270000.spi: cannot use DMA: -19
 tegra-qspi 3270000.spi: falling back to PIO

But I don't see the crash. However, on linux-6.1.y I do see the crash ...

 tegra-qspi 3270000.spi: cannot use DMA: -19
 tegra-qspi 3270000.spi: falling back to PIO
 tegra-qspi 3270000.spi: transfer timeout
 tegra-qspi 3270000.spi: error in transfer, fifo status 0x20400006
 CPU:0, Error: cbb-noc@2300000, irq=15

So I believe recent upstream changes in the Tegra210 QSPI driver have 
fixed this.

This series does fix the issue on linux-6.1.y but I believe that is 
because this is really enabling DMA support and so PIO is still broken. 
Ideally, PIO should work if DMA support is missing in device-tree.

IMO this series simply enables DMA support. May be we should clarify 
this in the commit message, but otherwise, I am fine with these changes.

Jon

--
nvpublic