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That's my point. Which is the right one? The answer is >> probably neither, but whatever is present on the bus. > > I think that defaulting to active-low is correct. The Tegra234 SPI > controller hardware defaults to active-low (all bits in CS_POL_INACTIVE > are set) so an active-high device is already asserted before this driver > initializes. I checked the controller drivers under drivers/spi/; they > either default to active-low or preserve the hardware default. I am a bit reluctant to make this change after 10+ years of this driver being around. > A more complex option is to scan the device tree children, check each > item for whether it uses native chip select (as opposed to GPIO CS) and > check for spi-cs-high. I found no other spi drivers that do this at > probe time, and I don't think it's worth the complexity, but I can send > it as a v2 if needed. Right. Although this patch is specific to Tegra, I am guessing that other devices could also face similar issues and therefore, it would seem that having a generic facility to scan the devices would be ideal. Jon -- nvpublic