linux-kernel - Re: [PATCH V6 0/8] make mt7623 clock of hdmi stable

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Message-ID: <1551837141.23995.13.camel@mtksdaap41>
Date:   Wed, 6 Mar 2019 09:52:21 +0800
From:   CK Hu <ck.hu@...iatek.com>
To:     wangyan wang <wangyan.wang@...iatek.com>
CC:     Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        "Philipp Zabel" <p.zabel@...gutronix.de>,
        David Airlie <airlied@...ux.ie>,
        "Daniel Vetter" <daniel@...ll.ch>,
        chunhui dai <chunhui.dai@...iatek.com>,
        "Colin Ian King" <colin.king@...onical.com>,
        Sean Wang <sean.wang@...iatek.com>,
        "Ryder Lee" <ryder.lee@...iatek.com>, <linux-clk@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-mediatek@...ts.infradead.org>,
        <dri-devel@...ts.freedesktop.org>, <srv_heupstream@...iatek.com>
Subject: Re: [PATCH V6 0/8] make mt7623 clock of hdmi stable

On Mon, 2019-02-25 at 10:09 +0800, wangyan wang wrote:
> From: Wangyan Wang <wangyan.wang@...iatek.com>
> 
> V6 adopt maintainer's suggestion.
> Here is the change list between V5 & V6
> 1. change "unsigned char mux_flags;" to "u8 mux_flags;" to
> match with the struct in " clk: mediatek: add MUX_GATE_FLAGS_2".
> 

Hi, Wangyan:

I'm not familiar with this clock system, so I still have some question
about it, if you could describe more clear, it would help us to speed up
this review process.

In [1], I find the clock that dpi and hdmi_phy controls,

	dpi0: dpi@...14000 {
		clocks = <&mmsys CLK_MM_DPI1_DIGL>,
			 <&mmsys CLK_MM_DPI1_ENGINE>,
			 <&topckgen CLK_TOP_TVDPLL>;
		clock-names = "pixel", "engine", "pll";
	};


	hdmi_phy: phy@...09100 {
		clocks = <&apmixedsys CLK_APMIXED_HDMI_REF>;
		clock-names = "pll_ref";
	};

In [2], You say that to prevent changing tvdpll would let hdmi stable,
and this clock is controlled by dpi, why do you modify the control flow
in hdmi_phy? If these two have relationship, please describe more clear
because I'm not familiar with this clock system.

And I think that patch 'drm/mediatek: using new factor for tvdpll in
MT2701' is the major patch to prevent modifying tvdpll because it reduce
the factor case. Does MT8173 has the same problem? Just ask, I does not
require you to modify MT8173 part.

[1]
https://github.com/frank-w/BPI-R2-4.14/blob/663f7def421952eb49b2d698eadaff12d02622d2/arch/arm/boot/dts/mt7623.dtsi
[2]
http://lists.infradead.org/pipermail/linux-mediatek/2019-February/017693.html


Regards,
CK


> 
> chunhui dai (8):
>   drm/mediatek: recalculate hdmi phy clock of MT2701 by querying
>     hardware
>   drm/mediatek: move the setting of fixed divider
>   drm/mediatek: using different flags of clk for HDMI phy
>   drm/mediatek: fix the rate and divder of hdmi phy for MT2701
>   clk: mediatek: add MUX_GATE_FLAGS_2
>   clk: mediatek: using CLK_MUX_ROUND_CLOSEST for the clock of dpi1_sel
>   drm/mediatek: using new factor for tvdpll in MT2701
>   drm/mediatek: fix the rate of parent for hdmi phy in MT2701
> 
>  drivers/clk/mediatek/clk-mt2701.c              |  4 +-
>  drivers/clk/mediatek/clk-mtk.c                 |  2 +-
>  drivers/clk/mediatek/clk-mtk.h                 | 20 ++++++---
>  drivers/gpu/drm/mediatek/mtk_dpi.c             |  8 ++--
>  drivers/gpu/drm/mediatek/mtk_hdmi_phy.c        | 34 ++++------------
>  drivers/gpu/drm/mediatek/mtk_hdmi_phy.h        |  7 +---
>  drivers/gpu/drm/mediatek/mtk_mt2701_hdmi_phy.c | 56 +++++++++++++++++++++++---
>  drivers/gpu/drm/mediatek/mtk_mt8173_hdmi_phy.c | 23 +++++++++++
>  8 files changed, 102 insertions(+), 52 deletions(-)
>