linux-kernel - Re: [PATCH v11 4/7] drm/sun4i: dsi: Handle bus clock explicitly

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Message-ID: <CAMty3ZCisTrFGjzHyqSofqFAsKSLV1n2xP5Li3Lonhdi0WUZVA@mail.gmail.com>
Date:   Tue, 29 Oct 2019 04:03:56 +0530
From:   Jagan Teki <jagan@...rulasolutions.com>
To:     Maxime Ripard <mripard@...nel.org>
Cc:     Chen-Yu Tsai <wens@...e.org>, David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Michael Trimarchi <michael@...rulasolutions.com>,
        Icenowy Zheng <icenowy@...c.io>,
        linux-sunxi <linux-sunxi@...glegroups.com>,
        dri-devel <dri-devel@...ts.freedesktop.org>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        devicetree <devicetree@...r.kernel.org>,
        linux-amarula <linux-amarula@...rulasolutions.com>
Subject: Re: [PATCH v11 4/7] drm/sun4i: dsi: Handle bus clock explicitly 

Hi Maxime,

On Mon, Oct 28, 2019 at 9:06 PM Maxime Ripard <mripard@...nel.org> wrote:
>
> On Fri, Oct 25, 2019 at 11:26:22PM +0530, Jagan Teki wrote:
> > Usage of clocks are varies between different Allwinner
> > DSI controllers. Clocking in A33 would need bus and
> > mod clocks where as A64 would need only bus clock.
> >
> > To support this kind of clocking structure variants
> > in the same dsi driver,
>
> There's no variance in the clock structure as far as the bus clock is
> concerned.
>
> > explicit handling of common clock would require since the A64
> > doesn't need to mention the clock-names explicitly in dts since it
> > support only one bus clock.
> >
> > Also pass clk_id NULL instead "bus" to regmap clock init function
> > since the single clock variants no need to mention clock-names
> > explicitly.
>
> You don't need explicit clock handling. Passing NULL as the argument
> in regmap_init_mmio_clk will make it use the first clock, which is the
> bus clock.

Indeed I tried that, since NULL clk_id wouldn't enable the bus clock
during regmap_mmio_gen_context code, passing NULL triggering vblank
timeout.