Re: [PATCH 04/12] drm/sun4i: sun6i_mipi_dsi: Enable missing DSI bus clock

[Jagan Teki <jagan@amarulasolutions.com>]

On Thu, Sep 27, 2018 at 6:13 PM Chen-Yu Tsai <wens@csie.org> wrote:
>
> Hi,
>
> On Thu, Sep 27, 2018 at 7:49 PM Jagan Teki <jagan@amarulasolutions.com> 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@amarulasolutions.com>
> > ---
> >  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.