linux-kernel - Re: [PATCH 2/2] clk: rockchip: remove ROCKCHIP_SOFTRST_HIWORD

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Date:	Fri, 3 Jun 2016 15:38:57 +0800
From:	Shawn Lin <shawn.lin@...k-chips.com>
To:	Heiko Stübner <heiko@...ech.de>
Cc:	shawn.lin@...k-chips.com, Xing Zheng <zhengxing@...k-chips.com>,
	linux-rockchip@...ts.infradead.org,
	Stephen Boyd <sboyd@...eaurora.org>,
	linux-kernel@...r.kernel.org, linux-clk@...r.kernel.org
Subject: Re: [PATCH 2/2] clk: rockchip: remove ROCKCHIP_SOFTRST_HIWORD_MASK
 for rockchip platform

在 2016/6/3 15:29, Heiko Stübner 写道:
> Hi Shawn,
>
> Am Freitag, 3. Juni 2016, 11:35:32 schrieb Shawn Lin:
>> 在 2016/6/3 9:25, Xing Zheng 写道:
>>> On 2016年06月03日 08:54, Shawn Lin wrote:
>>>> I check all the Socs including RK2928/3000/3066/3028X/316X/312X/
>>>> 3190/3188/3228/3368/3399/3036, and find all of them use high 16-bit
>>>> as write mask. Obviously we don't need ROCKCHIP_SOFTRST_HIWORD_MASK
>>>> any more(actually I don't know why we need it before). This patch
>>>> removes it to simplify the code and save a little cpu cycle when calling
>>>> assert or deassert callback.
>>>
>>> In my opinion, this flag can be used for compatibility, we can not
>>> ensure that our SoCs will not use the 32bit SOFTRST_CONs in future.
>>>
>>> Thanks.
>>
>> Thanks for sharing your thought.
>>
>> I'm not 100% sure, but I'm 99% sure about we won't let
>> it happened. You have to consider the backward compatibility
>> rather than the future ones. If you got a chip with 10 bit, or
>> 8bit for SOFTRST_CONX, so how do you wanna deal with it?
>> Should we now add  ROCKCHIP_SOFTRST_X_BIT_MASK?  :)
>
> older SoCs like the rk2818 (ARM9-based) do actually use 32bit softrst
> registers. And if I ever get my hands on one of those, I'd actually try to
> support it :-) .
>
> So I'd really like to keep the flag.

okay, fair engough. I just forgot to check rk281x and rk2808 etc, which
seems too old for me. Yes, IIRC it did use 32bit softrst...

So this flag should be used to keep the backward compatibility
if someday someone wanna upstream something for rk2818.. :)

please drop this patch.

>
> Heiko
>
>
>


-- 
Best Regards
Shawn Lin