linux-kernel - Re: [PATCH v7 1/4] soc: mediatek: Refine scpsys to support multiple platform

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Message-ID: <1468294448.31247.28.camel@mtksdaap41>
Date:	Tue, 12 Jul 2016 11:34:08 +0800
From:	James Liao <jamesjj.liao@...iatek.com>
To:	Matthias Brugger <matthias.bgg@...il.com>
CC:	Sascha Hauer <kernel@...gutronix.de>,
	Rob Herring <robh@...nel.org>,
	Kevin Hilman <khilman@...nel.org>,
	Daniel Kurtz <djkurtz@...omium.org>,
	<srv_heupstream@...iatek.com>, <devicetree@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>,
	<linux-mediatek@...ts.infradead.org>
Subject: Re: [PATCH v7 1/4] soc: mediatek: Refine scpsys to support multiple
 platform

Hi Matthias,

On Mon, 2016-07-11 at 15:10 +0200, Matthias Brugger wrote:
> 
> On 11/07/16 10:56, James Liao wrote:
> 
> [...]
> 
> >>>>> @@ -467,28 +386,54 @@ static int scpsys_probe(struct platform_device *pdev)
> >>>>>    			if (PTR_ERR(scpd->supply) == -ENODEV)
> >>>>>    				scpd->supply = NULL;
> >>>>>    			else
> >>>>> -				return PTR_ERR(scpd->supply);
> >>>>> +				return ERR_CAST(scpd->supply);
> >>>>>    		}
> >>>>>    	}
> >>>>>
> >>>>> -	pd_data->num_domains = NUM_DOMAINS;
> >>>>> +	pd_data->num_domains = num;
> >>>>>
> >>>>> -	for (i = 0; i < NUM_DOMAINS; i++) {
> >>>>> +	init_clks(pdev, clk);
> >>>>> +
> >>>>> +	for (i = 0; i < num; i++) {
> >>>>>    		struct scp_domain *scpd = &scp->domains[i];
> >>>>>    		struct generic_pm_domain *genpd = &scpd->genpd;
> >>>>>    		const struct scp_domain_data *data = &scp_domain_data[i];
> >>>>>
> >>>>> +		for (j = 0; j < MAX_CLKS && data->clk_id[j]; j++) {
> >>>>> +			struct clk *c = clk[data->clk_id[j]];
> >>>>> +
> >>>>> +			if (IS_ERR(c)) {
> >>>>> +				dev_err(&pdev->dev, "%s: clk unavailable\n",
> >>>>> +					data->name);
> >>>>> +				return ERR_CAST(c);
> >>>>> +			}
> >>>>> +
> >>>>> +			scpd->clk[j] = c;
> >>>>
> >>>> Put this in the else branch. Apart from that is there any reason you
> >>>
> >>> Do you mean to change like this?
> >>>
> >>> 	if (IS_ERR(c)) {
> >>> 		...
> >>> 		return ERR_CAST(c);
> >>> 	} else {
> >>> 		scpd->clk[j] = c;
> >>> 	}
> >>>
> >>> checkpatch.pl will warn for above code due to it returns in 'if' branch.
> >>>
> >>
> >> I tried that on top of next-20160706 and it checkpatch didn't throw any
> >> warning. Which kernel version are based on?
> >
> > I don't remember which version of checkpatch warn on this pattern. This
> > patch series develop across several kernel versions.
> 
> We as the kernel community develop against master or linux-next. We only 
> care about older kernel version in the sense that we intent hard not to 
> break any userspace/kernel or firmware/kernel interfaces. Apart from 
> that it's up to every individual to backport patches from mainline 
> kernel to his respective version. But that's nothing the community as a 
> hole can take care of.
> 
> >
> > So do you prefer to put "scpd->clk[j] = c;" into 'else' branch?
> >
> 
> Yes please :)

Yingjoe had tested in the latest checkpatch.pl and it showed checkpatch
warn on the else-branch. He had replied the results in previous email.
 
> >>>> moved the for up in the function? If not, I would prefer not to move it,
> >>>> to make it easier to read the diff.
> >>>
> >>> The new 'for' block are far different from original one. And I think
> >>> it's easy to read if we keep simple assign statements in the same block.
> >>>
> >>
> >> It's different in the sense that it checks if struct clk *c is an error.
> >> I don't see the reason why we need to move it up in the file.
> >> It's not too important but I would prefer not to move it if there is no
> >> reason.
> >
> > I think I may misunderstand your comments. Which 'for' block did you
> > mention for? 'for (i = 0; i < num ...' or 'for (j = 0; j < MAX_CLKS
> > && ...' ?
> >
> > The 'for(i)' exists in original code, this patch just change its counter
> > from 'NUM_DOMAINS' to 'num'. The 'for(j)' is a new for-block, so it was
> > not moved from other blocks.
> >
> 
> for (j = 0; j < MAX_CLKS... is present in the actual scpsys_probe in 
> linux-next (line 485 as of today). This patch moves this for a few lines 
> up, to be precise before executing this code sequence:
> <code>
> pd_data->domains[i] = genpd;
> scpd->scp = scp;
> 
> scpd->data = data;
> </code>
> 
> AFAIK there is no reason to do so. It adds unnecessary complexity to the 
> patch. So please fix this together with the other comments you got.

I see. So you prefer to put the for(j < MAX_CLKS) after 'scpd->data =
data' right? I can change it in next patch.


Best regards,

James