Hello Martin, On Mon Jan 12, 2026 at 11:21 PM CET, Martin Blumenstingl wrote: > Hi Luca, > > On Fri, Jan 9, 2026 at 11:03 AM Luca Ceresoli <[email protected]> > wrote: >> >> of_drm_find_bridge() is deprecated. Move to its replacement >> of_drm_find_and_get_bridge() which gets a bridge reference, and ensure it >> is put when done. >> >> dw_hdmi->bridge is used only in dw_hdmi_top_thread_irq(), so in order to >> avoid potential use-after-free ensure the irq is freed before putting the >> dw_hdmi->bridge reference. >> >> Acked-by: Maxime Ripard <[email protected]> >> Signed-off-by: Luca Ceresoli <[email protected]> > Reviewed-by: Martin Blumenstingl <[email protected]> > > [...] >> @@ -789,8 +789,12 @@ static void meson_dw_hdmi_unbind(struct device *dev, >> struct device *master, >> void *data) >> { >> struct meson_dw_hdmi *meson_dw_hdmi = dev_get_drvdata(dev); >> + struct platform_device *pdev = to_platform_device(dev); >> + int irq = platform_get_irq(pdev, 0); >> >> + devm_free_irq(dev, irq, meson_dw_hdmi); > I have one question (so I can understand things better): > is there a particular reason why you went with free'ing the IRQ > instead of "just" masking it (so the hardware won't fire anymore of > those IRQs)?
One reason is symmetry: _bind requests the irq, so _unbind does the reverse. Another is I don't have the hardware, so I wanted my changes to be as small and clear as possible. In principle one could request/free the irq in probe/remove and then enable/disable it in bind/unbind. Whether it would be a good or bad idea I don't know, but surely it would be more complex and I wouldn't want to do it without any chance to test it on hardware. Also, that would only optimize the case of multiple bind/unbind cycles, which are not quite realistic without bridge hotplug. And brigde hotplug does not exist yet in mainline, and when it will arrive it will be used only for a few use cases. I hope this answers your question. Best regards, Luca -- Luca Ceresoli, Bootlin Embedded Linux and Kernel engineering https://bootlin.com
