linux-kernel - Re: [PATCH/RFT v2 02/17] ARM: davinci: da8xx: Add CFGCHIP syscon platform declaration.

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Date:   Tue, 25 Oct 2016 10:53:12 -0500
From:   David Lechner <david@...hnology.com>
To:     Sekhar Nori <nsekhar@...com>, Axel Haslam <ahaslam@...libre.com>
Cc:     Greg KH <gregkh@...uxfoundation.org>,
        Johan Hovold <johan@...nel.org>, robh+dt@...nel.org,
        Alan Stern <stern@...land.harvard.edu>,
        Kevin Hilman <khilman@...libre.com>,
        Sergei Shtylyov <sshtylyov@...mvista.com>,
        manjunath.goudar@...aro.org, Mark Brown <broonie@...nel.org>,
        Alexandre Bailon <abailon@...libre.com>,
        linux-usb@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH/RFT v2 02/17] ARM: davinci: da8xx: Add CFGCHIP syscon
 platform declaration.

Hi Sekhar,

On 10/25/2016 05:17 AM, Sekhar Nori wrote:
> On Tuesday 25 October 2016 03:07 PM, Axel Haslam wrote:
>> Hi Sekar,
>>
>> On Tue, Oct 25, 2016 at 10:10 AM, Sekhar Nori <nsekhar@...com> wrote:
>>> On Monday 24 October 2016 10:16 PM, ahaslam@...libre.com wrote:
>>>> From: David Lechner <david@...hnology.com>
>>>>
>>>> The CFGCHIP registers are used by a number of devices, so using a syscon
>>>> device to share them. The first consumer of this will by the phy-da8xx-usb
>>>> driver.
>>>>
>>>> Signed-off-by: David Lechner <david@...hnology.com>
>>>> [Axel: minor fix: change id to -1]
>>>
>>> Can you please clarify this change? There could be other syscon devices
>>> on the chip for other common registers. Why use the singular device-id?
>>>
>>
>> in the case of non DT boot, the phy driver is looking for "syscon" :
>>
>> d_phy->regmap = syscon_regmap_lookup_by_pdevname("syscon");
>>
>> if we register the syscon driver with id = 0, the actual name of the syscon
>> device will be "syscon.0" and the phy driver will fail to probe, because
>> the strncmp match in the syscon driver (syscon_match_pdevname)
>> will fail.
>>
>> should i change the phy driver instead?
>
> Yes, please. Forcing only one syscon region for the whole chip will be
> too restrictive, I am pretty sure.
>
> Thanks,
> Sekhar
>

In the previous review, you requested that this be changed to -1 [1].

If we change it back to 0, it will also require reverting a patch to the 
phy driver that has already been merged[2].

[1]: http://www.gossamer-threads.com/lists/linux/kernel/2435807?page=last
[2]: http://www.gossamer-threads.com/lists/linux/kernel/2518804