Re: [PATCH] clk: tegra: mark TEGRA210_CLK_DBGAPB as always on

From: Geert Uytterhoeven
Date: Wed Mar 08 2017 - 06:42:09 EST

Hi Jon,

On Wed, Mar 8, 2017 at 11:13 AM, Jon Hunter <jonathanh@xxxxxxxxxx> wrote:
>> I had a similar issue with SH-Mobile AG5, where the power domain containing
>> the JTAG interface is powered down.
> This reminds me, does your patch assume that the DFD power domain is
> enabled? I am guessing that it needs to be for JTAG to work.

Yes. The pm-rmobile driver looks for "arm,coresight-etm3x" devices, and
marks the corresponding PM Domain as always-on, as long as the
Coresight code doesn't handle runtime PM.

For R-Mobile A1 and APE6 I already have added such device nodes, as any access
to a debug register hangs when the debug power domain is powered down.
For SH-Mobile AG5, I hadn't, as the debug power domain needs to be powered
for JTAG functionality only.

For the latter, perhaps we also need a command line parameter to change
a device status from "disabled" to "enabled"?



Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds