DMARC-Filter: OpenDMARC Filter v1.3.1 smtp.codeaurora.org DB5CF6156D
Date: Wed, 2 Nov 2016 10:59:44 -0700
From: "'Stephen Boyd'" <sboyd@codeaurora.org>
To: Sricharan <sricharan@codeaurora.org>
Cc: mturquette@baylibre.com, linux-clk@vger.kernel.org,
        linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org,
        rnayak@codeaurora.org, stanimir.varbanov@linaro.org
Subject: Re: [PATCH 1/3] clk: qcom: gdsc: Add support for gdscs with HW
 control
Message-ID: <20161102175944.GI16026@codeaurora.org>
References: <1477304297-5248-1-git-send-email-sricharan@codeaurora.org>
 <1477304297-5248-2-git-send-email-sricharan@codeaurora.org>
 <20161102001834.GB16026@codeaurora.org>
 <003c01d234d5$731b19c0$59514d40$@codeaurora.org>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <003c01d234d5$731b19c0$59514d40$@codeaurora.org>
User-Agent: Mutt/1.5.21 (2010-09-15)
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 1380
Lines: 38

On 11/02, Sricharan wrote:
> Hi Stephen,
> 
> >On 10/24, Sricharan R wrote:
> >> @@ -164,6 +171,10 @@ static int gdsc_enable(struct generic_pm_domain *domain)
> >>  	 */
> >>  	udelay(1);
> >>
> >> +	/* Turn on HW trigger mode if supported */
> >> +	if (sc->flags & HW_CTRL)
> >> +		gdsc_hwctrl(sc, true);
> >> +
> >
> >It sounds like this will cause glitches if the hardware isn't
> >asserting their hw control bit by default? This has me concerned
> >that we can't just throw the hw control enable part into here,
> >because that bit doesn't live in the clock controller, instead it
> >lives in the hw block that is powered by the power domain?
> >
> >Or does the power on reset value of that hw control signal
> >asserted? If that's true then we should be ok to force it into hw
> >control mode by default.
> >
> 
> The hw control bit is set by default. Instead its turned 'off'
> with the reset value. So it has to not 
> be turned 'on' at some point
> to put the gdsc in hw control if required. This bit is part of the
> gdscr register. So i did not quite understand the reason for the
> glitch here ?

I mean the reset value of the hw control signal inside the device
that is inside the GDSC power domain. For example, the hw control
bit inside the video core.

-- 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project