linux-kernel - Re: [PATCH 2/4] clk: qcom: Add clk_rcg2_gfx3d

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Date:   Mon, 06 Aug 2018 14:37:18 +0530
From:   Amit Nischal <anischal@...eaurora.org>
To:     Stephen Boyd <sboyd@...nel.org>
Cc:     Michael Turquette <mturquette@...libre.com>,
        Andy Gross <andy.gross@...aro.org>,
        David Brown <david.brown@...aro.org>,
        Rajendra Nayak <rnayak@...eaurora.org>,
        Odelu Kukatla <okukatla@...eaurora.org>,
        Taniya Das <tdas@...eaurora.org>,
        linux-arm-msm@...r.kernel.org, linux-soc@...r.kernel.org,
        linux-clk@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-clk-owner@...r.kernel.org
Subject: Re: [PATCH 2/4] clk: qcom: Add clk_rcg2_gfx3d_ops for SDM845

On 2018-08-03 04:14, Stephen Boyd wrote:
> Quoting Amit Nischal (2018-07-30 04:28:56)
>> On 2018-07-25 12:28, Stephen Boyd wrote:
>> >
>> > Ok. Sounds good! Is the rate range call really needed? It can't be
>> > determined in the PLL code with some table or avoided by making sure
>> > GPU
>> > uses OPP table with only approved frequencies?
>> >
>> 
>> Currently fabia PLL code does not have any table to check this and
>> intention
>> was to avoid relying on the client to call set_rate with only approved
>> frequencies so we have added the set_rate_range() call in the GPUCC
>> driver
>> in order to set the rate range.
>> 
> 
> But GPU will use OPP so it doesn't seem like it really buys us anything
> here. And it really doesn't matter when the clk driver implementation
> doesn't use the min/max to clamp the values of the round_rate() call. 
> Is
> that being done here? I need to double check. I would be more convinced
> if the implementation was looking at min/max to constrain the rate
> requested.
> 

So our understanding is that GPU(client) driver will always call the
set_rate with approved frequencies only and we can completely rely on 
the
client. Is our understanding is correct?

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