On 06/15/2016 09:13 PM, Rob Herring wrote:
> On Wed, Jun 15, 2016 at 11:45 AM, Philipp Zabel <p.zabel@xxxxxxxxxxxxxx> wrote:
>> Hi Andrew,
>>
>> Am Mittwoch, den 15.06.2016, 10:48 -0500 schrieb Andrew F. Davis:
>>> On 06/01/2016 01:41 PM, Andrew F. Davis wrote:
>>>> Some SoCs contain reset controls for modules that are memory-mapped to
>>>> areas shared with other module configuration settings. This requires
>>>> synchronization across all drivers accessing this memory area. This
>>>> series adds a generic SYSCON reset driver to allow resets toggled
>>>> by bits in memory-mapped registers through SYSCON.
>>>>
>>>> Changes from v2:
>>>> - Rebased on v4.7-rc1
>>>> - Removed the need to give reset specifier nodes an index address
>>>>
>>>> Changes from v1:
>>>> - Reset control information is now described in the reset node, this
>>>> keeps the reset information centralized for easy verification
>>>> - Other small fixups
>>>>
>>>> Andrew F. Davis (2):
>>>> Documentation: dt: reset: Add syscon reset binding
>>>> reset: add a SYSCON based reset driver
>>>>
>>>> .../devicetree/bindings/reset/syscon-reset.txt | 105 ++++++++
>>>> drivers/reset/Kconfig | 10 +
>>>> drivers/reset/Makefile | 1 +
>>>> drivers/reset/reset-syscon.c | 289 +++++++++++++++++++++
>>>> include/dt-bindings/reset/syscon.h | 23 ++
>>>> 5 files changed, 428 insertions(+)
>>>> create mode 100644 Documentation/devicetree/bindings/reset/syscon-reset.txt
>>>> create mode 100644 drivers/reset/reset-syscon.c
>>>> create mode 100644 include/dt-bindings/reset/syscon.h
>>>>
>>>
>>> Is there any additional feedback for this driver? I normally try to
>>> refrain from pings, but this may begin to block further upstreaming of
>>> IPs that uses this reset if it can not be taken this cycle.
>>
>> There's still Rob's concern that this binding needs a device tree node
>> per single register bit in the worst case, which seems a bit overkill.
>
> Yes, that's still my concern with this.
>
>> I'd still prefer to have this information hidden in the drivers, but if
>> you absolutely have to put it in the device tree, maybe an approach more
>> similar to pinctrl-simple, where you could list all resets, one per
>> line, in a single property, would be more acceptable:
>>
>> pscrst: reset-controller {
>> compatible = "ti,<chip>-pscrst", "syscon-reset";
>>
>> /* syscon-reset,bits = <ctrl_reg ctrl_bit stat_reg stat_bit flags>; */
>
> ti,reset-bits
>
>> syscon-reset,bits = <0xa3c 8 0x83c 8 RESET_ASSERT_CLEAR /* 0: pcrst-dsp */
>> 0xa40 5 0 0 RESET_TRIGGER_SET>; /* 1: pcrst-example */
>> };
>>
>> dsp0: dsp {
>> resets = <&pscrst 0>;
>> };
>
> Otherwise, this seems okay. It is more concise.
>
If this is what you would both be okay with then I'll do it this way,
pushing v4 in a moment.
>>
>>> If there is still an objection to calling this a generic reset solution
>>> we would not strongly object to relabeling this to something implying
>>> more TI exclusivity.
>>
>> Good. Right now there don't seem to be that many reset controllers in
>> the wild for which this binding would be a good fit. If this turns out
>> to be useful for others, we can add more compatibles to the driver.
>
> Certainly other users would make a generic solution more compelling.
>
I believe some other current reset drivers could have made use of this
without having resorted to new drivers, I guess we will have to just
wait to see if it gets traction with new platforms or not, before we can
decide if this solution is really as general as I think it can be.
Andrew
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