Re: [PATCH 4/9] drm/omapdrm: use drm_bridge_chain_get_last_bridge()

[Luca Ceresoli <luca.ceresoli@bootlin.com>]

Hi Maxime,

On Fri, 25 Jul 2025 16:15:23 +0200
Maxime Ripard <mripard@kernel.org> wrote:

> On Mon, Jul 14, 2025 at 12:32:40PM +0200, Luca Ceresoli wrote:
> > Hi Maxime,
> > 
> > On Thu, 10 Jul 2025 09:13:46 +0200
> > Maxime Ripard <mripard@kernel.org> wrote:
> >   
> > > On Wed, Jul 09, 2025 at 06:48:03PM +0200, Luca Ceresoli wrote:  
> > > > Use drm_bridge_chain_get_last_bridge() instead of open coding a loop with
> > > > two invocations of drm_bridge_get_next_bridge() per iteration.
> > > > 
> > > > Besides being cleaner and more efficient, this change is necessary in
> > > > preparation for drm_bridge_get_next_bridge() to get a reference to the
> > > > returned bridge.
> > > > 
> > > > Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>
> > > > ---
> > > >  drivers/gpu/drm/omapdrm/omap_drv.c | 8 ++++----
> > > >  1 file changed, 4 insertions(+), 4 deletions(-)
> > > > 
> > > > diff --git a/drivers/gpu/drm/omapdrm/omap_drv.c b/drivers/gpu/drm/omapdrm/omap_drv.c
> > > > index 054b71dba6a75b8c42198c4b102a093f43a675a2..3bbcec01428a6f290afdfa40ef6f79629539a584 100644
> > > > --- a/drivers/gpu/drm/omapdrm/omap_drv.c
> > > > +++ b/drivers/gpu/drm/omapdrm/omap_drv.c
> > > > @@ -378,12 +378,12 @@ static int omap_display_id(struct omap_dss_device *output)
> > > >  	struct device_node *node = NULL;
> > > >  
> > > >  	if (output->bridge) {
> > > > -		struct drm_bridge *bridge = output->bridge;
> > > > -
> > > > -		while (drm_bridge_get_next_bridge(bridge))
> > > > -			bridge = drm_bridge_get_next_bridge(bridge);
> > > > +		struct drm_bridge *bridge =
> > > > +			drm_bridge_chain_get_last_bridge(output->bridge->encoder);
> > > >  
> > > >  		node = bridge->of_node;
> > > > +
> > > > +		drm_bridge_put(bridge);    
> > > 
> > > Any reason you're not using __free(drm_bridge_put) here?  
> > 
> > Just because the code is simple enough that an explicit
> > drm_bridge_put() is clearly sufficient.
> > 
> > Do you think __free() should be used even in such trivial cases?  
> 
> It's a matter of opinion at this point :)
> 
> It' makes it a bit easier and consistent so that's why I raised it, but
> if you feel like it's too much, that's fine by me as well.

In the end I chose to use __free here as well for v2, for consistency
over the series.

Luca

-- 
Luca Ceresoli, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com