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

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Message-ID: <acdfef83-8778-e8f4-e423-ed04a9a8a649@ti.com>
Date:   Mon, 11 Jun 2018 11:38:44 +0530
From:   Faiz Abbas <faiz_abbas@...com>
To:     Tony Lindgren <tony@...mide.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

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?

> 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.

Thanks,
Faiz