Re: [PATCH] spi: tegra114: initialize native chip selects inactive
Abraham Zukor <[email protected]> Tue, 28 Jul 2026 13:03:12 -0700
| Newsgroups | org.kernel.vger.linux-tegra,org.kernel.vger.linux-kernel,org.kernel.vger.linux-spi |
|---|---|
| Message-ID | <[email protected]> |
On 28/07/2026 10:34, Jon Hunter wrote: > Exactly. 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. 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. Thanks, Abe