From: harigovi@codeaurora.org
To: Jeffrey Hugo <jeffrey.l.hugo@gmail.com>
Cc: "open list:DRM PANEL DRIVERS" <dri-devel@lists.freedesktop.org>,
MSM <linux-arm-msm@vger.kernel.org>,
freedreno <freedreno@lists.freedesktop.org>,
DTML <devicetree@vger.kernel.org>,
lkml <linux-kernel@vger.kernel.org>,
Rob Clark <robdclark@gmail.com>,
nganji@codeaurora.org, Sean Paul <seanpaul@chromium.org>,
kalyan_t@codeaurora.org,
"Kristian H. Kristensen" <hoegsberg@chromium.org>
Subject: Re: [Freedreno] [v1] drm/msm/dsi/pll: call vco set rate explicitly
Date: Fri, 07 Feb 2020 18:08:39 +0530 [thread overview]
Message-ID: <2f5abc857910f70faa119fea5bda81d7@codeaurora.org> (raw)
In-Reply-To: <CAOCk7Nr9n-xLtWq=LEM-QFhJcY+QOuzazsoi-yjErA9od2Jwmw@mail.gmail.com>
On 2020-02-06 20:29, Jeffrey Hugo wrote:
> On Thu, Feb 6, 2020 at 2:13 AM Harigovindan P <harigovi@codeaurora.org>
> wrote:
>>
>> For a given byte clock, if VCO recalc value is exactly same as
>> vco set rate value, vco_set_rate does not get called assuming
>> VCO is already set to required value. But Due to GDSC toggle,
>> VCO values are erased in the HW. To make sure VCO is programmed
>> correctly, we forcefully call set_rate from vco_prepare.
>
> Is this specific to certain SoCs? I don't think I've observed this.
As far as Qualcomm SOCs are concerned, since pll is analog and the value
is directly read from hardware if we get recalc value same as set rate
value, the vco_set_rate will not be invoked. We checked in our idp
device which has the same SOC but it works there since the rates are
different.
next prev parent reply other threads:[~2020-02-07 12:38 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-06 9:12 [v1] drm/msm/dsi/pll: call vco set rate explicitly Harigovindan P
2020-02-06 14:59 ` [Freedreno] " Jeffrey Hugo
2020-02-07 12:38 ` harigovi [this message]
2020-02-07 14:10 ` Jeffrey Hugo
2020-02-11 5:58 ` harigovi
2020-02-11 15:44 ` Rob Clark
2020-02-11 15:59 ` Jeffrey Hugo
2020-02-12 0:28 ` Rob Clark
2020-02-12 4:05 ` Jeffrey Hugo
2020-02-12 5:10 ` Rob Clark
2020-02-17 10:42 ` harigovi
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