On Mon, Aug 18, 2014 at 6:34 PM, Stephen Warren <swarren@xxxxxxxxxxxxx> wrote: > On 08/13/2014 03:19 AM, Lucas Stach wrote: >> >> Hi Stephen, >> >> sorry for getting on this late, I completely missed this and only now >> stumbled upon this. >> >> I'm not really fond of this change. The barebox bootloader completely >> probes itself from DT, including the pinmux. We try to stay as close as >> possible to the upstream kernel DTs and only introduce minimal changes. >> Removing the pinmux from the DTS will completely break barebox, as we >> don't have any static pinmux tables there. >> >> In order to not break the bootloader use-case I strongly advocate to >> keep the static pinmux in the DT. Can't we just rename the the state to >> something like "initial", so Linux won't try to set it by default? This >> way we could still keep the information in the DT, while being able to >> say "if you are going to program the initial pinmux state you need to >> follow the sequence defined by NVIDIA syseng". >> >> This obviously would make the naming of the state part of the binding, >> but I think this may be acceptable. > > > Linus, what do you think of Lucas's proposal? I guess we say the DTs should be neutral to OS, whether they should be neutral to the use case for boot loaders is another question, but I think the more info is in the DT, the better actually as it avoids spreading relevant information across places where it's hard-coded. > As background, the Tegra HW design implies that all initial pinmux setup > should be applied one time early during boot before peripherals are used. > That means it should happen early in boot code, not once an OS like Linux > has been loaded, since loading the OS requires use of at least some > peripheral(s). Hence, there's no point the kernel re-applying the same > configuration. > > I had suggested (in this patch) removing the pinmux completely from the DT, > since no OS should need it. However, the Barebox bootloader is configured > via DT, and so wants to keep the pinmux configuration in the DT, rather than > embedding the pinmux tables into the bootloader's board support code. Lucas > has suggested simply changing the pinmux state name in the DT so that the > kernel won't apply the pinmux configuration yet it's still there for the > bootloader to use if it wants. > > I'd suggest "boot" rather than "initial" myself for the new state name, but > that's just bike-shedding. I'm game for "boot". Yours, Linus Walleij -- To unsubscribe from this list: send the line "unsubscribe linux-tegra" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
