Re: [PATCH v2 01/11] clk: tegra: Switch to using critical clks

On Wed, Jun 22, 2016 at 02:16:30PM +0200, Thierry Reding wrote:

* PGP Signed by an unknown key

On Fri, May 27, 2016 at 04:38:04PM -0400, Rhyland Klein wrote:

quoted

Mark some of the required-to-be-enabled clks as critical clks. These
need to be kept on through the disabling of unused clks during init.
They may not get any reference before or after init, but are required
to be on, therefore let the core enable them.

Signed-off-by: Rhyland Klein <redacted>
---
v2:
 - Remove mention of HAND_OFF clks as they are not supported yet.

 drivers/clk/tegra/clk-tegra-periph.c     | 21 ++++++++++++++-------
 drivers/clk/tegra/clk-tegra-super-gen4.c | 12 +++++++-----
 2 files changed, 21 insertions(+), 12 deletions(-)

I have some difficulty to follow why some of these clocks are critical.
It might help if the commit message mentioned why each of these need to
remain enabled forever, even if never used.

Also, it's fairly unlikely that pll_p for example would ever get
disabled because a bunch of others are derived from it. I'm also not
quite convinced yet that it really is critical. What does it drive which
isn't claimed by any drivers?

mselect and sclk are clocked from pll_p, however we don't have drivers for
those. Most other peripherals clocked from pll_p can be clockgated by their
driver which can lead to pll_p being turned off causing the system to hang.

Cheers,

Peter.