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

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Message-ID: <f904dc9b-d723-f466-0ee4-78af920ccd72@gmail.com>
Date:	Tue, 12 Jul 2016 10:21:13 +0200
From:	Matthias Brugger <matthias.bgg@...il.com>
To:	James Liao <jamesjj.liao@...iatek.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



On 12/07/16 05:34, James Liao wrote:
> 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.
>

Yes you are right. Not sure what I was testing. Sorry for that.

>>>>>> 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.
>

Ok, thanks.

Regards,
Matthias