linux-kernel - Re: [PATCH v3 4/6] bus: ti-sysc: Add support for software reset

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Message-ID: <20180611060957.GN5738@atomide.com>
Date:   Sun, 10 Jun 2018 23:09:57 -0700
From:   Tony Lindgren <tony@...mide.com>
To:     Faiz Abbas <faiz_abbas@...com>
Cc:     linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
        linux-omap@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-clk@...r.kernel.org, mark.rutland@....com, paul@...an.com,
        t-kristo@...com, robh+dt@...nel.org, bcousson@...libre.com
Subject: Re: [PATCH v3 4/6] bus: ti-sysc: Add support for software reset

* Faiz Abbas <faiz_abbas@...com> [180611 06:09]:
> Hi Tony,
> 
> On Friday 08 June 2018 11:51 AM, Tony Lindgren wrote:
> > * Faiz Abbas <faiz_abbas@...com> [180607 10:24]:
> >> Hi,
> >>
> >> On Thursday 07 June 2018 01:05 PM, Tony Lindgren wrote:
> >>> * Faiz Abbas <faiz_abbas@...com> [180606 06:14]:
> >>>> +static int sysc_reset(struct sysc *ddata)
> >>>> +{
> >>>> +	int offset = ddata->offsets[SYSC_SYSCONFIG];
> >>>> +	int val = sysc_read(ddata, offset);
> >>>> +
> >>>> +	val |= (0x1 << ddata->cap->regbits->srst_shift);
> >>>> +	sysc_write(ddata, offset, val);
> >>>> +
> >>>> +	/* Poll on reset status */
> >>>> +	if (ddata->cfg.quirks & SYSC_QUIRK_RESET_STATUS) {
> >>>> +		offset = ddata->offsets[SYSC_SYSSTATUS];
> >>>> +
> >>>> +		return readl_poll_timeout(ddata->module_va + offset, val,
> >>>> +				(val & ddata->cfg.syss_mask) == 0x0,
> >>>> +				100, MAX_MODULE_SOFTRESET_WAIT);
> >>>> +	}
> >>>> +
> >>>> +	return 0;
> >>>> +}
> >>>
> >>> I wonder if we should also add SYSS_QUIRK_RESET_STATUS in
> >>> addition to SYSC_QUIRK_RESET status to make it easy to
> >>> read the right register?
> >>
> >> I assumed SYSC_QUIRK is the prefix to indicate the ti-sysc driver not
> >> the register. Are there layouts in which the reset status bit is in the
> >> sysconfig register rather than the sysstatus register?
> > 
> > Yes we can have reset status bit in either syss or syssconfig register.
> 
> You mean sysstatus and sysconfig right?

Yup.

> > We detect that in sysc_init_syss_mask() but we should also set something
> > at that point to make it clear which reset to use. But as we don't need
> > the quirk flag, it's probably set a function pointer after the detection.
> > So how about let's have two functions sysc_reset() and sysc_syss_reset()
> > and then we can implement sysc_syss_reset() in a separate patch after
> > testing it when we have a non-platform data using example for
> > sysc_syss_reset().
> > 
> 
> Shouldn't the function I add be called sysc_syss_reset()? The reset
> status bit is in the sysstatus.

Yes

Tony