[PATCH] drm/amd/display: Check hpd_gpio for NULL before accessing it

[Alex Deucher]

On Thu, Feb 7, 2019 at 3:14 PM Alex Deucher <alexdeucher at gmail.com> wrote:
>
> On Thu, Feb 7, 2019 at 3:12 PM Harry Wentland <harry.wentland at amd.com> wrote:
> >
> > dal_gpio_open and dal_gpio_unlock_pin dereference hpd_gpio.
> > Check for NULL before calling those functions.
> >
> > Fixes: e261568f94d6 ("drm/amd/display: add gpio lock/unlock")
> > Reported-by: Przemek Socha <soprwa at gmail.com>
> > CC: Chiawen Huang <chiawen.huang at amd.com>
> > CC: Tony Cheng <Tony.Cheng at amd.com>
> > Signed-off-by: Harry Wentland <harry.wentland at amd.com>
>
> Acked-by: Alex Deucher <alexander.deucher at amd.com>
>

Just tried it on a bonaire.
Tested-by: Alex Deucher <alexander.deucher at amd.com>

> > ---
> >
> > I don't have a system to test this on. Can someone give it a spin?
> >
> > Harry
> >
> >  drivers/gpu/drm/amd/display/dc/core/dc_link.c | 7 ++++---
> >  1 file changed, 4 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/amd/display/dc/core/dc_link.c b/drivers/gpu/drm/amd/display/dc/core/dc_link.c
> > index 6d2cef05b4d7..7f5a947ad31d 100644
> > --- a/drivers/gpu/drm/amd/display/dc/core/dc_link.c
> > +++ b/drivers/gpu/drm/amd/display/dc/core/dc_link.c
> > @@ -1127,10 +1127,11 @@ static bool construct(
> >                 link->dc->res_pool->funcs->link_init(link);
> >
> >         link->hpd_gpio = get_hpd_gpio(link->ctx->dc_bios, link->link_id, link->ctx->gpio_service);
> > -       dal_gpio_open(link->hpd_gpio, GPIO_MODE_INTERRUPT);
> > -       dal_gpio_unlock_pin(link->hpd_gpio);
> > -       if (link->hpd_gpio != NULL)
> > +       if (link->hpd_gpio != NULL) {
> > +               dal_gpio_open(link->hpd_gpio, GPIO_MODE_INTERRUPT);
> > +               dal_gpio_unlock_pin(link->hpd_gpio);
> >                 link->irq_source_hpd = dal_irq_get_source(link->hpd_gpio);
> > +       }
> >
> >         switch (link->link_id.id) {
> >         case CONNECTOR_ID_HDMI_TYPE_A:
> > --
> > 2.19.1
> >