linux-kernel - Re: [PATCH v2 2/2] usb: dwc2: host: Clear interrupts before handling them

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Message-ID: <877fldg8d9.fsf@saruman.tx.rr.com>
Date:	Thu, 19 Nov 2015 12:19:14 -0600
From:	Felipe Balbi <balbi@...com>
To:	Doug Anderson <dianders@...omium.org>,
	John Youn <John.Youn@...opsys.com>
CC:	Yunzhi Li <lyz@...k-chips.com>,
	Heiko Stübner <heiko@...ech.de>,
	"open list:ARM/Rockchip SoC..." <linux-rockchip@...ts.infradead.org>,
	Julius Werner <jwerner@...omium.org>,
	"Herrero, Gregory" <gregory.herrero@...el.com>,
	"Kaukab, Yousaf" <yousaf.kaukab@...el.com>,
	Dinh Nguyen <dinguyen@...nsource.altera.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	"linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 2/2] usb: dwc2: host: Clear interrupts before handling them


Hi,

Doug Anderson <dianders@...omium.org> writes:
>>>> isn't this a regression ? You're first clearing the interrupts and only
>>>> then reading to check what's pending, however, what's pending has just
>>>> been cleared. Seems like this should be:
>>>>
>>>> hprt0 = dwc2_readl(HPRT0);
>>>> dwc2_writeal(PRTINT, GINTSTS);
>>>
>>> Actually, we could probably remove the setting of GINTSTS_PRTINT
>>> completely.  The docs I have say that the GINTSTS_PRTINT is read only
>>> and that:
>>>
>>>> The core sets this bit to indicate a change in port status of one of the
>>>> DWC_otg core ports in Host mode. The application must read the
>>>> Host Port Control and Status (HPRT) register to determine the exact
>>>> event that caused this interrupt. The application must clear the
>>>> appropriate status bit in the Host Port Control and Status register to
>>>> clear this bit.
>>>
>>> ...so writing PRTINT is probably useless, but John can confirm.
>>>
>>
>> Yup, it seems it can be removed.
>
> How do you guys want this handled?  Should I send up a new version of
> this patch?  ...or should I send a followon patch that does this
> removal?

I'll leave the final decision to John, but my opinion is that a new
version of the patch would be preferrable.

-- 
balbi

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