linux-kernel - Re: [PATCH] ARM: dts: imx7d: fix LCDIF clock assignment

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Date:   Wed, 23 Nov 2016 21:02:25 -0200
From:   Fabio Estevam <festevam@...il.com>
To:     Stefan Agner <stefan@...er.ch>
Cc:     Shawn Guo <shawnguo@...nel.org>,
        Sascha Hauer <kernel@...gutronix.de>,
        Mark Rutland <mark.rutland@....com>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        Peter Chen <peter.chen@...escale.com>,
        Fabio Estevam <fabio.estevam@....com>,
        Liu Ying <Ying.Liu@...escale.com>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH] ARM: dts: imx7d: fix LCDIF clock assignment

On Tue, Nov 22, 2016 at 10:42 PM, Stefan Agner <stefan@...er.ch> wrote:
> The eLCDIF IP of the i.MX 7 SoC knows multiple clocks and lists them
> separately:
>
> Clock      Clock Root              Description
> apb_clk    MAIN_AXI_CLK_ROOT       AXI clock
> pix_clk    LCDIF_PIXEL_CLK_ROOT    Pixel clock
> ipg_clk_s  MAIN_AXI_CLK_ROOT       Peripheral access clock
>
> All of them are switched by a single gate, which is part of the
> IMX7D_LCDIF_PIXEL_ROOT_CLK clock. Hence using that clock also for
> the AXI bus clock (clock-name "axi") makes sure the gate gets
> enabled when accessing registers.
>
> There seem to be no separate AXI display clock, and the clock is
> optional. Hence remove the dummy clock.
>
> This fixes kernel freezes when starting the X-Server (which
> disables/re-enables the display controller).
>
> Signed-off-by: Stefan Agner <stefan@...er.ch>

Reviewed-by: Fabio Estevam <fabio.estevam@....com>