[PATCH v2 07/12] drm: bridge: samsung-dsim: Add module init, exit

[Jagan Teki]

On Mon, May 9, 2022 at 5:35 PM Marek Szyprowski
<m.szyprowski at samsung.com> wrote:
>
> On 04.05.2022 13:40, Jagan Teki wrote:
> > Add module init and exit functions for the bridge to register
> > and unregister dsi_driver.
> >
> > Exynos drm driver stack will register the platform_driver separately
> > in the common of it's exynos_drm_drv.c including dsi_driver.
> >
> > Register again would return -EBUSY, so return 0 for such cases as
> > dsi_driver is already registered.
> >
> > v2, v1:
> > * none
> >
> > Signed-off-by: Jagan Teki <jagan at amarulasolutions.com>
> > ---
> >   drivers/gpu/drm/bridge/samsung-dsim.c | 22 ++++++++++++++++++++++
> >   1 file changed, 22 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/bridge/samsung-dsim.c b/drivers/gpu/drm/bridge/samsung-dsim.c
> > index 8f9ae16d45bc..b618e52d0ee3 100644
> > --- a/drivers/gpu/drm/bridge/samsung-dsim.c
> > +++ b/drivers/gpu/drm/bridge/samsung-dsim.c
> > @@ -1740,6 +1740,28 @@ struct platform_driver dsi_driver = {
> >       },
> >   };
> >
> > +static int __init samsung_mipi_dsim_init(void)
> > +{
> > +     int ret;
> > +
> > +     ret = platform_driver_register(&dsi_driver);
> > +
> > +     /**
> > +      * Exynos drm driver stack will register the platform_driver
> > +      * separately in the common of it's exynos_drm_drv.c including
> > +      * dsi_driver. Register again would return -EBUSY, so return 0
> > +      * for such cases as dsi_driver is already registered.
> > +      */
> > +     return ret == -EBUSY ? 0 : ret;
> > +}
> > +module_init(samsung_mipi_dsim_init);
>
> I've just noticed this. The above approach is really a bad pattern:
> registering the same driver 2 times and relying on the error.

If it tries to register 2nd time, then it returns EBUSY so we are
returning 0 for that case. not sure why it registers 2nd time again.

Jagan.