On Mon, 21 Mar 2022 at 19:21, Vinod Polimera vpolimer@qti.qualcomm.com wrote:
-----Original Message----- From: Stephen Boyd swboyd@chromium.org Sent: Friday, March 18, 2022 2:41 AM To: quic_vpolimer quic_vpolimer@quicinc.com; devicetree@vger.kernel.org; dri-devel@lists.freedesktop.org; freedreno@lists.freedesktop.org; linux-arm-msm@vger.kernel.org Cc: linux-kernel@vger.kernel.org; robdclark@gmail.com; dmitry.baryshkov@linaro.org; dianders@chromium.org; quic_kalyant quic_kalyant@quicinc.com Subject: Re: [PATCH v6 1/5] drm/msm/disp/dpu1: set mdp clk to the maximum frequency in opp table during probe
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Quoting Vinod Polimera (2022-03-14 07:46:53)
use max clock during probe/bind sequence from the opp table. The clock will be scaled down when framework sends an update.
Capitalize 'use'.
Why is it important to use max frequency during probe/bind? Does not setting the clk rate during probe mean that we'll never use the max rate? Does it speed things up during probe?
We need to vote mdp clock during probe/bind so that rails are not set at undetermined state as pointed out by Dmitry. Since we dont know what will be the rate set in boot loader, it would be ideal to vote at max frequency. There could be a firmware display programmed in bootloader and we want to transition it to kernel without underflowing.
This should be expressed in the commit message.