linux-kernel - Re: [PATCH 2/3] Input: snvs_pwrkey

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Date:   Mon, 10 Feb 2020 09:55:54 -0800
From:   Dmitry Torokhov <dmitry.torokhov@...il.com>
To:     Horia Geanta <horia.geanta@....com>
Cc:     Robin Gong <yibin.gong@....com>,
        André Draszik <git@...red.net>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Anson Huang <anson.huang@....com>,
        Aymen Sghaier <aymen.sghaier@....com>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        "David S. Miller" <davem@...emloft.net>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        "linux-crypto@...r.kernel.org" <linux-crypto@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-input@...r.kernel.org" <linux-input@...r.kernel.org>,
        dl-linux-imx <linux-imx@....com>
Subject: Re: [PATCH 2/3] Input: snvs_pwrkey - enable snvs clock as needed

On Mon, Feb 10, 2020 at 06:33:30AM +0000, Horia Geanta wrote:
> On 2/10/2020 4:03 AM, Robin Gong wrote:
> > On 2020/02/10 Dmitry Torokhov <dmitry.torokhov@...il.com> wrote: 
> >> On Fri, Feb 07, 2020 at 08:10:22AM +0000, Horia Geanta wrote:
> >>> On 1/30/2020 10:45 PM, André Draszik wrote:
> >>>> @@ -140,6 +148,25 @@ static int imx_snvs_pwrkey_probe(struct
> >> platform_device *pdev)
> >>>>  	if (pdata->irq < 0)
> >>>>  		return -EINVAL;
> >>>>
> >>>> +	pdata->clk = devm_clk_get(&pdev->dev, "snvs-pwrkey");
> >>>> +	if (IS_ERR(pdata->clk)) {
> >>>> +		pdata->clk = NULL;
> >>> Using devm_clk_get_optional() would simplify error handling.
> >>
> >> It sounds to me that this clock is not at all optional and the driver currently
> >> "works" only by accident and therefore optional is not suitable here.
> > Yes, then we need to add all snvs clk in dts for on legacy i.MX chips in this patchset
> > to avoid any potential function broken.

How many are there? I am not too terribly opposed of having the driver
handle missing clk if there are very many legacy DTSes out there. But
then we need to handle it properly (i.e. current iteration does not
handle referral properly for example).

> In that case the DT binding should be updated too,
> to make the clock mandatory.

I think this should be done in either case, as as far I understand the
part can not function without the clock and it worked purely by chance
on some systems as something else was turning the clock on.

Thanks.

-- 
Dmitry