On Wed, 6 Aug 2025 17:38:17 +0800
Liu Ying <victor....@nxp.com> wrote:
> On 08/06/2025, Luca Ceresoli wrote:
> > Hello Liu,
> >
> > On Wed, 6 Aug 2025 16:54:24 +0800
> > Liu Ying <victor....@nxp.com> wrote:
> >
> >> devm_drm_bridge_alloc() returns ERR_PTR on failure instead of a
> >> NULL pointer, so use IS_ERR() to check the returned pointer.
> >>
> >> Fixes: 48f05c3b4b70 ("drm/bridge: analogix_dp: Use devm_drm_bridge_alloc()
> >> API")
> >> Signed-off-by: Liu Ying <victor....@nxp.com>
> >> ---
> >> drivers/gpu/drm/bridge/analogix/analogix_dp_core.c | 2 +-
> >> 1 file changed, 1 insertion(+), 1 deletion(-)
> >>
> >> diff --git a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
> >> b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
> >> index ed35e567d117..86cf898a09bb 100644
> >> --- a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
> >> +++ b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
> >> @@ -1474,7 +1474,7 @@ analogix_dp_probe(struct device *dev, struct
> >> analogix_dp_plat_data *plat_data)
> >>
> >> dp = devm_drm_bridge_alloc(dev, struct analogix_dp_device, bridge,
> >> &analogix_dp_bridge_funcs);
> >> - if (!dp)
> >> + if (IS_ERR(dp))
> >> return ERR_PTR(-ENOMEM);
> >
> > Good catch, thanks!
> >
> > You fix is correct but now I realized one additional fix is needed in
> > the following line:
> >
> > - return ERR_PTR(-ENOMEM);
> > + return ERR_PTR(dp);
>
> You mean ERR_CAST(dp)?
Ah, indeed!
> > Can you send a v2 with that fixed?
>
> I find devm_drm_bridge_alloc() always returns ERR_PTR(-ENOMEM) in this
> driver context, so it seems fine to keep the existing ERR_PTR(-ENOMEM).
> If you prefer ERR_CAST(dp), I may send v2 to use ERR_CAST(dp).
The documentation says:
* Returns:
* Pointer to new bridge, or ERR_PTR on failure.
So let's follow that, which is a (relatively) immutable contract, and
not the implementation which might change over time.
This is also what all callers of devm_drm_bridge_alloc() do, unless I
missed something.
Thanks,
Luca
--
Luca Ceresoli, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
