On 04/15/2013 10:50 AM, Axel Lin wrote:
My understanding is for shared mode regulators:
It can be in LP mode only when *BOTH* are in LP mode.
If only one of the regulator in HP mode, then *BOTH* should be in HP mode.
Did I misunderstand something?
Your understanding is correct.
Let me put this issue this way:
Current code behavior:
get_mode() returns IDLE if only one lp_mode_req flag is true, but mode
register value is HP.
AB8540_LDO_ANAMIC1 AB8540_LDO_ANAMIC2 mode register
get_mode() returns
lp_mode_req=true lp_mode_req=true HP
REGULATOR_MODE_NORMAL
lp_mode_req=true lp_mode_req=false HP
REGULATOR_MODE_IDLE
lp_mode_req=false lp_mode_req=true HP
REGULATOR_MODE_IDLE
lp_mode_req=false lp_mode_req=false LP
REGULATOR_MODE_IDLE
I think it looks like this:
AB8540_LDO_ANAMIC1 AB8540_LDO_ANAMIC2 mode register
get_mode() returns
lp_mode_req=true lp_mode_req=true LP
REGULATOR_MODE_IDLE REGULATOR_MODE_IDLE
lp_mode_req=true lp_mode_req=false HP
REGULATOR_MODE_IDLE REGULATOR_MODE_NORMAL
lp_mode_req=false lp_mode_req=true HP
REGULATOR_MODE_NORMAL REGULATOR_MODE_IDLE
lp_mode_req=false lp_mode_req=false HP
REGULATOR_MODE_NORMAL REGULATOR_MODE_NORMAL
with this path:
mode register value is consistent with get_mode().
AB8540_LDO_ANAMIC1 AB8540_LDO_ANAMIC2 mode register
get_mode() returns
lp_mode_req=true lp_mode_req=true HP
REGULATOR_MODE_NORMAL
lp_mode_req=true lp_mode_req=false HP
REGULATOR_MODE_NORMAL
lp_mode_req=false lp_mode_req=true HP
REGULATOR_MODE_NORMAL
lp_mode_req=false lp_mode_req=false LP
REGULATOR_MODE_IDLE
And like this:
AB8540_LDO_ANAMIC1 AB8540_LDO_ANAMIC2 mode register
get_mode() returns
lp_mode_req=true lp_mode_req=true LP
REGULATOR_MODE_IDLE REGULATOR_MODE_IDLE
lp_mode_req=true lp_mode_req=false HP
REGULATOR_MODE_NORMAL REGULATOR_MODE_NORMAL
lp_mode_req=false lp_mode_req=true HP
REGULATOR_MODE_NORMAL REGULATOR_MODE_NORMAL
lp_mode_req=false lp_mode_req=false HP
REGULATOR_MODE_NORMAL REGULATOR_MODE_NORMAL
I guess what you don't like with the current approach is that the driver
returns REGULATOR_MODE_IDLE in some cases where the mode register is set to LP.
But I think, with patch applied, the control may be wrong in some cases because
the regulator framework will call get_mode and see that the mode is already
correct and not call set_mode so lp_mode_req will not get updated. I realised
my previous example was incorrect so here I describe another example:
0. Start condition:
ANAMIC1 is requested in LP mode (lp_mode_req=true) and ANAMIC2 is requested in
HP mode (lp_mode_req=false).
So the mode register is set to HP.
1. Now ANAMIC1 is requested to HP mode from consumer side. The regulator
framework checks the current mode with get_mode which returns HP. So the
regulator framework returns without calling set_mode because the mode is
already correct.
For ANAMIC1 lp_mode_req=true and for ANAMIC2 lp_mode_req=false (still).
The mode register will be correct at HP.
2. If ANAMIC2 is now requested to LP mode from consumer side, the regulator
framework calls get_mode which returns HP, so the framework calls set_mode.
In set_mode, the function checks the other regulator's status which is
lp_mode_req=true. So the function will continue and set the regulator in LP
mode even if it should not be.
Bengt
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