Re: [PATCH v3] drm/exynos: enable FIMD clocks

[Inki Dae <inki.dae@xxxxxxxxxxx>]

2013/4/22 Vikas Sajjan <vikas.sajjan@xxxxxxxxxx>

Hi Mr Dae,

On 22 April 2013 11:19, Inki Dae <inki.dae@xxxxxxxxxxx> wrote:

Hi, Mr. Vikas

Please fix the below typos Viresh pointed out and my comments.

> -----Original Message-----
> From: Viresh Kumar [mailto:viresh.kumar@xxxxxxxxxx]
> Sent: Monday, April 01, 2013 5:51 PM
> To: Vikas Sajjan
> Cc: dri-devel@xxxxxxxxxxxxxxxxxxxxx; linux-samsung-soc@xxxxxxxxxxxxxxx;
> jy0922.shim@xxxxxxxxxxx; inki.dae@xxxxxxxxxxx; kgene.kim@xxxxxxxxxxx;
> linaro-kernel@xxxxxxxxxxxxxxxx; linux-media@xxxxxxxxxxxxxxx
> Subject: Re: [PATCH v3] drm/exynos: enable FIMD clocks
>
> On 1 April 2013 14:13, Vikas Sajjan <vikas.sajjan@xxxxxxxxxx> wrote:
> > While migrating to common clock framework (CCF), found that the FIMD
> clocks
>
> s/found/we found/
>
> > were pulled down by the CCF.
> > If CCF finds any clock(s) which has NOT been claimed by any of the
> > drivers, then such clock(s) are PULLed low by CCF.
> >
> > By calling clk_prepare_enable() for FIMD clocks fixes the issue.
>
> s/By calling/Calling/
>
> and
>
> s/the/this
>
> > this patch also replaces clk_disable() with clk_disable_unprepare()
>
> s/this/This
>
> > during exit.
>
> Sorry but your log doesn't say what you are doing. You are just adding
> relevant calls to clk_prepare/unprepare() before calling
> clk_enable/disable.
>

  I shall modify the commit message as below as suggested by tomaz figa,

  " Common Clock Framework introduced the need to prepare clocks before
enabling them, otherwise clk_enable() fails. This patch adds clk_prepare
calls to the driver. This patch also removes clk_disable() from fimd_remove() as it will be done by pm_runtime_put_sync".
 

> > Signed-off-by: Vikas Sajjan <vikas.sajjan@xxxxxxxxxx>
> > ---
> > Changes since v2:
> >         - moved clk_prepare_enable() and clk_disable_unprepare() from
> >         fimd_probe() to fimd_clock() as suggested by Inki Dae
> <inki.dae@xxxxxxxxxxx>
> > Changes since v1:
> >         - added error checking for clk_prepare_enable() and also
replaced
> >         clk_disable() with clk_disable_unprepare() during exit.
> > ---
> >  drivers/gpu/drm/exynos/exynos_drm_fimd.c |   14 +++++++-------
> >  1 file changed, 7 insertions(+), 7 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/exynos/exynos_drm_fimd.c
> b/drivers/gpu/drm/exynos/exynos_drm_fimd.c
> > index 9537761..f2400c8 100644
> > --- a/drivers/gpu/drm/exynos/exynos_drm_fimd.c
> > +++ b/drivers/gpu/drm/exynos/exynos_drm_fimd.c
> > @@ -799,18 +799,18 @@ static int fimd_clock(struct fimd_context *ctx,
> bool enable)
> >         if (enable) {
> >                 int ret;
> >
> > -               ret = clk_enable(ctx->bus_clk);
> > +               ret = clk_prepare_enable(ctx->bus_clk);
> >                 if (ret < 0)
> >                         return ret;
> >
> > -               ret = clk_enable(ctx->lcd_clk);
> > +               ret = clk_prepare_enable(ctx->lcd_clk);
> >                 if  (ret < 0) {
> > -                       clk_disable(ctx->bus_clk);
> > +                       clk_disable_unprepare(ctx->bus_clk);
> >                         return ret;
> >                 }
> >         } else {
> > -               clk_disable(ctx->lcd_clk);
> > -               clk_disable(ctx->bus_clk);
> > +               clk_disable_unprepare(ctx->lcd_clk);
> > +               clk_disable_unprepare(ctx->bus_clk);
> >         }
> >
> >         return 0;
> > @@ -981,8 +981,8 @@ static int fimd_remove(struct platform_device *pdev)
> >         if (ctx->suspended)
> >                 goto out;
> >
> > -       clk_disable(ctx->lcd_clk);
> > -       clk_disable(ctx->bus_clk);
> > +       clk_disable_unprepare(ctx->lcd_clk);
> > +       clk_disable_unprepare(ctx->bus_clk);

Just remove the above codes. It seems that clk_disable(also
clk_disable_unprepare) isn't needed because it will be done by
pm_runtime_put_sync and please re-post it(probably patch v5??)

   So you mean I should work on v3 version, and keep  the clk_prepare_enable() code as is in fimd_clock() and just remove the clk_disable_unprepare() and also clk_disable() from fimd_remove(), right?

Right, please post it. And adding clk_enable() to probe() is another issue so this could be discussed later. As is this patch is needed for CCF support.

 

Viresh and Tomaz Figa, let me know if these changes are fine with you guys.

Thanks,
Inki Dae

>
> You are doing things at the right place but i have a suggestion. Are you
> doing
> anything in your clk_prepare() atleast for this device? Probably not.
>
> If not, then its better to call clk_prepare/unprepare only once at
> probe/remove
> and keep clk_enable/disable calls as is.
>
> --
> viresh

--
Thanks and Regards

 Vikas Sajjan

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