From mboxrd@z Thu Jan  1 00:00:00 1970
From: Jagan Teki <jagan-dyjBcgdgk7Pe9wHmmfpqLFaTQe2KTcn/@public.gmane.org>
Subject: Re: [PATCH 04/12] drm/sun4i: sun6i_mipi_dsi: Enable
 missing DSI bus clock
Date: Thu, 27 Sep 2018 19:14:23 +0530
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To: Chen-Yu Tsai <wens-jdAy2FN1RRM@public.gmane.org>
Cc: Maxime Ripard <maxime.ripard-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org>, Icenowy Zheng <icenowy-h8G6r0blFSE@public.gmane.org>, Jernej Skrabec <jernej.skrabec-gGgVlfcn5nU@public.gmane.org>, Vasily Khoruzhick <anarsoul-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>, Rob Herring <robh+dt-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>, Mark Rutland <mark.rutland-5wv7dgnIgG8@public.gmane.org>, Catalin Marinas <catalin.marinas-5wv7dgnIgG8@public.gmane.org>, Will Deacon <will.deacon-5wv7dgnIgG8@public.gmane.org>, David Airlie <airlied-cv59FeDIM0c@public.gmane.org>, dri-devel <dri-devel-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org>, Michael Turquette <mturquette-rdvid1DuHRBWk0Htik3J/w@public.gmane.org>, Stephen Boyd <sboyd-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>, linux-clk <linux-clk-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>, Michael Trimarchi <michael-dyjBcgdgk7Pe9wHmmfpqLFaTQe2KTcn/@public.gmane.org>, linux-arm-kernel <linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org>, devicetree <devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>, linux-kernel <linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>, linux-sunxi <linux-sunxi-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org>
List-Id: devicetree@vger.kernel.org

On Thu, Sep 27, 2018 at 6:13 PM Chen-Yu Tsai <wens-jdAy2FN1RRM@public.gmane.org> wrote:
>
> Hi,
>
> On Thu, Sep 27, 2018 at 7:49 PM Jagan Teki <jagan-dyjBcgdgk7Pe9wHmmfpqLFaTQe2KTcn/@public.gmane.org> wrote:
> >
> > DSI bus_clk is already available in sun6i_dsi but missed to
> > get the clk and process for enable/disable.
> >
> > This patch add support for it.
> >
> > Signed-off-by: Jagan Teki <jagan-dyjBcgdgk7Pe9wHmmfpqLFaTQe2KTcn/@public.gmane.org>
> > ---
> >  drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c | 8 ++++++++
> >  1 file changed, 8 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c b/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c
> > index 8e9c76febca2..156b371243c6 100644
> > --- a/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c
> > +++ b/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c
> > @@ -1004,6 +1004,12 @@ static int sun6i_dsi_probe(struct platform_device *pdev)
> >                 return PTR_ERR(dsi->reset);
> >         }
> >
> > +       dsi->bus_clk = devm_clk_get(dev, "bus");
> > +       if (IS_ERR(dsi->bus_clk)) {
> > +               dev_err(dev, "Couldn't get the DSI bus clock\n");
> > +               return PTR_ERR(dsi->bus_clk);
> > +       }
> > +
>
> The DSI driver uses devm_regmap_init_mmio_clk, which enables the
> clock behind the scenes when regmap access needs it enabled.
>
> Did you have any issues without this patch?

I'm unable to read register values via devmem, I see all 0's for all
dsi reg space.