linux-kernel - Re: [PATCH v3 3/8] soc: Mediatek: Add SCPSYS CPU power domain driver

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Message-ID: <20150806100311.GP18700@pengutronix.de>
Date:	Thu, 6 Aug 2015 12:03:11 +0200
From:	Sascha Hauer <s.hauer@...gutronix.de>
To:	Scott Shu <scott.shu@...iatek.com>
Cc:	Matthias Brugger <matthias.bgg@...il.com>,
	Mark Rutland <mark.rutland@....com>,
	devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org, linux-mediatek@...ts.infradead.org,
	wsd_upstream@...iatek.com, loda.chou@...iatek.com,
	jades.shih@...iatek.com, Mars.Cheng@...iatek.com,
	scott.shu@...il.com, djkurtz@...omium.org
Subject: Re: [PATCH v3 3/8] soc: Mediatek: Add SCPSYS CPU power domain driver

On Thu, Aug 06, 2015 at 10:59:02AM +0800, Scott Shu wrote:
> On Wed, 2015-08-05 at 10:50 +0200, Sascha Hauer wrote:
> > don't do this then it indeed doesn't make much sense to put it into the
> > same file.
> > 
> > From what I see we would need to change the prototype to something like
> > 
> > static int __scpsys_power_on(struct scp_domain_data *)
> > 
> > (maybe with some additional base addresses and stuff)
> > 
> > struct scp_domain_data would additionally need sram_isoint_b and sram_ckiso
> > members.
> > 
> > Sascha
> > 
> Hi Sascha,
>    The CPU power sequence is quite different with the others, as
> described below.
> 
> * Non-CPU
>    1) Set PWR_ON_BIT, PWR_ON_2ND_BIT
>    2) Wait PWR_ACK
>    3) Clear PWR_CLK_DIS_BIT
>    4) Clear PWR_ISO_BIT
>    5) Set PWR_RST_B_BIT
>    6) Clear SRAM_PDN
>    7) Wait SRAM_PDN_ACK
> * CPU
>    1) Set PWR_ON_BIT, PWR_ON_2ND_BIT
>    2) Wait PWR_ACK
>    3) Clear PWR_ISO_BIT
>    4) Clear L1_PDN to power on L1
>    5) Wait L1_PDN_ACK
>    6) Set SRAM_ISOINT_B
>    7) Clear SRAM_CKISO
>    8) Clear PWR_CLK_DIS
>    9) Set PWR_RST_B
> For multi-cluster SoC, the cluster power sequence is also different.
> 
> Please think if this is a good idea if we integrate the CPU support into
> the scpsys_power_on()? Based on the readability and compatible
> considerations, we provide this patch.

Maybe it's best if you go back to the v1 layout and put your scpsys code
to arch/arm/mach-mediatek/. While I think it's possible to share some
more code I am not sure anymore if this buys us something. We'll know in
the future.

Sascha


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