Re: [PATCH] spi: tegra114: initialize native chip selects inactive
Jon Hunter <[email protected]> Tue, 28 Jul 2026 10:34:52 +0100
| Newsgroups | org.kernel.vger.linux-tegra,org.kernel.vger.linux-kernel,org.kernel.vger.linux-spi |
|---|---|
| Message-ID | <[email protected]> |
On 28/07/2026 03:53, Abraham Zukor wrote: > On 27/07/2026 13:07, Jon Hunter wrote: >> What about the case where the SPI devices CS is active high or a >> mixture of the two? > > An all-active-high bus is the case the window gets right today: probe > writes zero to the field, so an active-high CS idles deasserted and an > active-low one sits asserted. This patch inverts that. No single > constant covers a mixed board - one polarity or the other is asserted > until tegra_spi_setup() runs for that device - so the question is > which default is the right one, and active low is what the SPI core > assumes when a device says nothing. Exactly. That's my point. Which is the right one? The answer is probably neither, but whatever is present on the bus. -- nvpublic