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

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Date:   Mon, 11 Jun 2018 11:57:35 +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



On Monday 11 June 2018 11:39 AM, Tony Lindgren wrote:
> * 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
> 

Great. I thought I completely misunderstood you. But I don't see what
adding another function will accomplish. A QUIRK flag used in the same
function would work well enough.

Regards,
Faiz