linux-kernel - Re: [PATCH v3 2/4] crypto: mxs-dcp

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Date:   Tue, 16 Oct 2018 17:23:11 +0000
From:   Leonard Crestez <leonard.crestez@....com>
To:     "festevam@...il.com" <festevam@...il.com>
CC:     dl-linux-imx <linux-imx@....com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        Fabio Estevam <fabio.estevam@....com>,
        Aymen Sghaier <aymen.sghaier@....com>,
        Franck Lenormand <franck.lenormand@....com>,
        "mark.rutland@....com" <mark.rutland@....com>,
        "shawnguo@...nel.org" <shawnguo@...nel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "davem@...emloft.net" <davem@...emloft.net>,
        Horia Geanta <horia.geanta@....com>,
        "kernel@...gutronix.de" <kernel@...gutronix.de>,
        "herbert@...dor.apana.org.au" <herbert@...dor.apana.org.au>,
        "marek.vasut@...il.com" <marek.vasut@...il.com>,
        "linux-crypto@...r.kernel.org" <linux-crypto@...r.kernel.org>
Subject: Re: [PATCH v3 2/4] crypto: mxs-dcp - Add support for dcp clk

On Tue, 2018-10-16 at 13:03 -0300, Fabio Estevam wrote:
> > +       /* DCP clock is optional, only used on some SOCs */
> > +       sdcp->dcp_clk = devm_clk_get(dev, "dcp");
> > +       if (IS_ERR(sdcp->dcp_clk)) {
> > +               if (sdcp->dcp_clk != ERR_PTR(-ENOENT))
> > +                       return PTR_ERR(sdcp->dcp_clk);
> > +               sdcp->dcp_clk = NULL;
> 
> This dcp_clk assignment to NULL does not seem to be necessary.

The clk API ignores all calls if clk == NULL (which is very nice) but
not if IS_ERR(clk). Setting dcp_clk to NULL avoids sprinkling other
checks.

> > +       ret = clk_prepare_enable(sdcp->dcp_clk);
> > +       if (ret)
> > +               return ret;
> > 
> >         ret = devm_request_irq(dev, dcp_vmi_irq, mxs_dcp_irq, 0,
> >                                "dcp-vmi-irq", sdcp);
> >         if (ret) {
> >                 dev_err(dev, "Failed to claim DCP VMI IRQ!\n");
> 
> In case of subsequent errors you should call
> clk_disable_unprepare(sdcp->dcp_clk).

Yes, will resend. Maybe some day clk consumer will automatically undo
pending prepare/enables on release?