On Thursday 08 May 2014 01:23 PM, Tero Kristo wrote:
On 05/08/2014 09:02 AM, Archit Taneja wrote:
On Tuesday 06 May 2014 07:56 PM, Tony Lindgren wrote:
* Archit Taneja <archit@xxxxxx> [140505 22:24]:
Hi,
On Monday 21 April 2014 08:40 PM, Tony Lindgren wrote:
* Archit Taneja <archit@xxxxxx> [140420 22:16]:
Hi,
On Friday 18 April 2014 10:48 PM, Tony Lindgren wrote:
* Archit Taneja <archit@xxxxxx> [140416 06:20]:
Add DT node for the ctrl-core sub module of the DRA7 control
module. We map the
CTRL_MODULE_CORE address region up to 0x4a002d60, this region
contains register
fields which configure clocks. The remainder of the registers are
related to
pad configurations or cross-bar configurations, and therefore
aren't mapped.
Can you please check if this can just use the existing
regmap syscon mapping:
syscon = <&dra7_ctrl_general>;
See how the drivers/regulator/pbias-regulator.c is using the
syscon to initialize a regulator and then omap_hsmmc.c just does
the standard regulator calls.
The thing is that this bit needs to be set before the the DSS
hwmods are
reset, and that happens very early. If we don't do this, DSS won't
reset
properly, and not get back to an idle state.
I am not sure where I can configure the syscon register early
enough that it
happens before the hwmods are reset. With a syscon mapping, I guess
we would
access the register when the DSS driver is probed. But that's too
late for
us.
Ideally, it would be much better to have a syscon mapping. Do you
have any
suggestions how this can be achieved very early in boot?
It's best to move the reset and initialization of DSS happen later.
I believe
we already are resetting only some of the hwmods early on.
I looked at this in some more detail. With the current hwmod
flags(HWMOD_INIT_NO_RESET/NO_IDLE), we still try to enable the IP,
it's just
the reset part(ocp reset/custom reset and sysc register) or the
disable part
that is skipped. hwmod still tries to enable the IP.
This again results in the same issue.
One thing which wasn't clear was that why do we enable a hwmod in the
first
place, if we know that we are going to skip reset?
Probably to configure the idle bits. In general, we should configure the
modules lazily as the driver probes as requested, and then idle the
unused modules with a late_initcall.
Okay, we were thinking of changing the hwmod code to skip enable for
hwmods(which have the HWMOD_INIT_NO_RESET flag) altogether. But that
doesn't seem like a viable option.
I can't think of any other way of getting around this, besides making
control module a clock provider.
Paul said that it's not that bad to make DRA7 CTRL module a clock
provider, but outside of PRCM code. I guess that would involve having
something along the lines of of_prcm_init() in mach-omap2/control.c
That sounds like pretty much one of the things I have done here:
https://github.com/t-kristo/linux-pm/tree/3.14-rc4-cm-prm-driver-wip
The patches in their current form haven't been posted yet though, as
they are waiting for some of the pre-reqs, but feel free to re-use
something from here.
Ah nice, thanks!
Archit
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