Re: [PATCH V2] arm64: dts: qcom: sc7280: Add nodes for eMMC and SD card

From: sbhanu@codeaurora.org
To: Doug Anderson <dianders@google.com>
Cc: Veerabhadrarao Badiganti <vbadigan@codeaurora.org>,
	Adrian Hunter <adrian.hunter@intel.com>,
	Ulf Hansson <ulf.hansson@linaro.org>,
	Rob Herring <robh+dt@kernel.org>,
	Asutosh Das <asutoshd@codeaurora.org>,
	Sahitya Tummala <stummala@codeaurora.org>,
	Ram Prakash Gupta <rampraka@codeaurora.org>,
	Sayali Lokhande <sayalil@codeaurora.org>,
	sartgarg@codeaurora.org, Rajendra Nayak <rnayak@codeaurora.org>,
	Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org>,
	Sibi Sankar <sibis@codeaurora.org>,
	cang@codeaurora.org, pragalla@codeaurora.org,
	nitirawa@codeaurora.org,
	Linux MMC List <linux-mmc@vger.kernel.org>,
	LKML <linux-kernel@vger.kernel.org>,
	linux-arm-msm <linux-arm-msm@vger.kernel.org>,
	"open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
	<devicetree@vger.kernel.org>, Andy Gross <agross@kernel.org>,
	Bjorn Andersson <bjorn.andersson@linaro.org>
Subject: Re: [PATCH V2] arm64: dts: qcom: sc7280: Add nodes for eMMC and SD card
Date: Tue, 13 Apr 2021 16:29:16 +0530	[thread overview]
Message-ID: <8126e130e5c0ea1e7ea867414f0510c0@codeaurora.org> (raw)
In-Reply-To: <CAD=FV=Wa4fT5wZgd0==8kLy_tzTLgdZ-HwdfOEAM9pMeMjjFyg@mail.gmail.com>

On 2021-03-29 20:26, Doug Anderson wrote:
> Hi,
> 
> On Thu, Mar 25, 2021 at 11:57 PM <sbhanu@codeaurora.org> wrote:
>> 
>> >>> +                       max-frequency = <192000000>;
>> >> Why do you need to specify this?
>> This helps to avoid lower speed modes running in high clock rate,
>> and As Veerabhadrarao Badiganti mentioned
> 
> Just to be clear, both Stephen and I agree that you should remove
> "max-frequency" here (see previous discussion). Bjorn is, of course,
> the file decision maker. However, unless he says "yeah, totally keep
> it in" I'd suggest dropping it from the next version.
> 
sure will drop in next version.
> 
>> >>> +                                       required-opps =
>> >>> <&rpmhpd_opp_low_svs>;
>> >>> +                                       opp-peak-kBps = <1200000
>> >>> 76000>;
>> >>> +                                       opp-avg-kBps = <1200000
>> >>> 50000>;
>> >> Why are the kBps numbers so vastly different than the ones on sc7180
>> >> for the same OPP point. That implies:
>> >>
>> >> a) sc7180 is wrong.
>> >>
>> >> b) This patch is wrong.
>> >>
>> >> c) The numbers are essentially random and don't really matter.
>> >>
>> >> Can you identify which of a), b), or c) is correct, or propose an
>> >> alternate explanation of the difference?
>> >>
>> 
>> We calculated bus votes values for both sc7180 and sc7280 with ICB 
>> tool,
>> above mentioned values we got for sc7280.
> 
> I don't know what an ICB tool is. Please clarify.
> 
> Also: just because a tool spits out numbers that doesn't mean it's
> correct. Presumably the tool could be wrong or incorrectly configured.
> We need to understand why these numbers are different.
> 
we checked with ICB tool team on this they conformed as Rennell & Kodiak 
are different chipsets,
we might see delta in ib/ab values due to delta in scaling factors.

> -Doug