Message-ID: <54D406BA.6060403@ti.com>
Date:	Thu, 5 Feb 2015 18:11:38 -0600
From:	Suman Anna <s-anna@...com>
To:	Bjorn Andersson <bjorn@...o.se>
CC:	Ohad Ben-Cohen <ohad@...ery.com>,
	Mark Rutland <mark.rutland@....com>,
	Rob Herring <robherring2@...il.com>,
	Kumar Gala <galak@...eaurora.org>,
	Josh Cartwright <joshc@...eaurora.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-omap@...r.kernel.org" <linux-omap@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	Rob Herring <robh+dt@...nel.org>
Subject: Re: [PATCH v7 1/4] Documentation: dt: add common bindings for hwspinlock

Hi Bjorn,

On 02/05/2015 05:01 PM, Bjorn Andersson wrote:
> On Mon, Feb 2, 2015 at 1:07 PM, Suman Anna <s-anna@...com> wrote:
>> On 02/01/2015 11:55 AM, Bjorn Andersson wrote:
>>> On Fri, Jan 30, 2015 at 9:41 PM, Ohad Ben-Cohen <ohad@...ery.com> wrote:
>>>> On Sat, Jan 31, 2015 at 1:29 AM, Bjorn Andersson <bjorn@...o.se> wrote:
>>>>> In a system where you have two hwlock blocks lckA and lckB, each
>>>>> consisting of 8 locks and you have dspB that can only access lckB
>>>>
>>>> This is a good example - thanks. To be able to cope with such cases we
>>>> will have to pass a hwlock block reference and its relative lock id.
>>>>
>>>
>>> Correct, so the #hwlock-cells and hwlock part from the proposal are
>>> the important one. Having an optional hwlock-names will make things
>>> easier to read as well, but is not necessary.
>>
>> Right, if anything, it would be useful only for the clients, but the
>> hwspinlock core itself would not need it. So, I would forgo adding the
>> hwlock-names for now.
>>
>>>
>>>> The DT binding should definitely be prepared for such cases (just kill
>>>> the base-id field?), but let's see what it means about the Linux
>>>> implementation.
>>>>
>>>
>>> From the dt binding PoV, we should be able to skip num-locks as well.
>>> It seems most hwlock blocks have a fixed amount of locks provided and
>>> the drivers are reporting this to the core when registering.
>>
>> I added this originally based on the initial MSM HW Mutex block bindings.
>>
> 
> It's not entirely correct to have this in DT for the MSM HW, as the
> hardware has a fixed number of mutexes. As soon as we have the binding
> sorted out I will follow up with a new revision of the tcsr/sfpb-mutex
> driver.
> 
>>>
>>> So I think we can reduce the binding to:
>>>
>>> Providers:
>>> #hwlock-cells
>>>
>>> Consumers:
>>> hwlocks
>>> hwlock-names
>>>
>>> For the hardware where number of locks is actually variable (e.g.
>>> different variants of same block) there can be driver specific entries
>>> for this.
>>
>> Right, we should be able to drop this and use the driver match data. As
>> it is, the field is used during registration of the block with the
>> hwspinlock core.
>>
> 
> If we have certain systems where it actually is a property to be
> configured then they can have individual properties, extending the
> standard set. Either way, it's not a dynamic property shared by all
> hwlock drivers, so it should not be in the common binding.
> 
> Will you send out a new revision of the binding? I would love to get
> this integrated so I can move on with the dependents.

Yep, will do as soon as I hear from Ohad on what to do with the patch
"hwspinlock/core: maintain a list of registered hwspinlock banks" that I
dropped from v7. Without that and dropping hwlock-base-id, I can't get
the translations done.

regards
Suman

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