Re: [PATCH 1/3] dt/bindings: arm-pl330: add description of arm,pl330-periph-burst

From: Shawn Lin <shawn.lin@rock-chips.com>
To: Lars-Peter Clausen <lars@metafoo.de>, Vinod Koul <vinod.koul@intel.com>
Cc: shawn.lin@rock-chips.com, Rob Herring <robh+dt@kernel.org>,
	Huibin Hong <huibin.hong@rock-chips.com>,
	Xing Zheng <zhengxing@rock-chips.com>,
	devicetree@vger.kernel.org, dianders@chromium.org,
	briannorris@chromium.org, Caesar Wang <wxt@rock-chips.com>,
	dmaengine@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	linux-rockchip@lists.infradead.org
Subject: Re: [PATCH 1/3] dt/bindings: arm-pl330: add description of arm,pl330-periph-burst
Date: Wed, 17 Aug 2016 16:11:03 +0800	[thread overview]
Message-ID: <55e596a0-4176-4277-40cc-1d26763a8be0@rock-chips.com> (raw)
In-Reply-To: <1d42542f-c43c-5c4b-01b7-ba0ca085004a@rock-chips.com>

Hi, Vinod and Lars-Peter

Ping.. Any better idea to share :)

On 2016/8/9 17:12, Shawn Lin wrote:
> Hi Lars-Peter,
>
> 在 2016/8/9 16:39, Lars-Peter Clausen 写道:
>> On 08/05/2016 09:25 AM, Shawn Lin wrote:
>>> Hi Vinod,
>>>
>>> 在 2016/8/5 11:34, Vinod Koul 写道:
>>>> On Fri, Aug 05, 2016 at 10:53:20AM +0800, Shawn Lin wrote:
>>>>> This patch adds the "arm,pl330-periph-burst" for arm-pl330 to
>>>>> support busrt mode.
>>>>
>>>> why should this be DT property. Only reason I can think of if some hw
>>>> versions support this and some won't.
>>>
>>> yes, if we want to support burst mode, both of the master(pl330) and
>>> client(several peripherals) should implement it, otherwise it will
>>> be broken when enabling.
>>
>> As you said, it is up to the consumer peripheral whether it supports
>> BURST,
>> SINGLE or both. So this is a per client property, but you specify this
>> as a
>> a global property on the producer side.
>
> Thanks for comment.
>
> yup, but what is the proper way to add it ? :)
>
>
> a) If pl330 support BURST as well as all the peripherals, we could
> enable it.
>
> b) If pl300 support BURST, but all the peripherals don't support it,
> we could not enable it.
>
> c) If pl300 support BURST, but not all the peripherals support it,
> we also could not enable it.
>
> the burst feature of peripheral IP may be vendor-specific, but the
> common driver for this peripheral are used for many many vendors which
> means we could not check all of this info. It's very likely to break
> them... I couldn't figure out how many upstreamed peripheral drivers
> who are using pl300 either.
>
> So this check should be done by all this vendors but we could make
> sure we don't break them before they check a), b), c), right?
>
>
>>
>>
>>
>>
>
>

-- 
Best Regards
Shawn Lin