Re: [PATCH v2] drm/bridge: ti-sn65dsi86: Fix auxiliary bus lifetime

[Doug Anderson]

Hi,

On Tue, Jun 13, 2023 at 11:41 AM Stephen Boyd <swboyd@xxxxxxxxxxxx> wrote:
>
> Quoting Douglas Anderson (2023-06-13 06:58:13)
> > Memory for the "struct device" for any given device isn't supposed to
> > be released until the device's release() is called. This is important
> > because someone might be holding a kobject reference to the "struct
> > device" and might try to access one of its members even after any
> > other cleanup/uninitialization has happened.
> >
> > Code analysis of ti-sn65dsi86 shows that this isn't quite right. When
> > the code was written, it was believed that we could rely on the fact
> > that the child devices would all be freed before the parent devices
> > and thus we didn't need to worry about a release() function. While I
> > still believe that the parent's "struct device" is guaranteed to
> > outlive the child's "struct device" (because the child holds a kobject
> > reference to the parent), the parent's "devm" allocated memory is a
> > different story. That appears to be freed much earlier.
> >
> > Let's make this better for ti-sn65dsi86 by allocating each auxiliary
> > with kzalloc and then free that memory in the release().
> >
> > Fixes: bf73537f411b ("drm/bridge: ti-sn65dsi86: Break GPIO and MIPI-to-eDP bridge into sub-drivers")
> > Suggested-by: Stephen Boyd <swboyd@xxxxxxxxxxxx>
> > Signed-off-by: Douglas Anderson <dianders@xxxxxxxxxxxx>
> > ---
>
> Reviewed-by: Stephen Boyd <swboyd@xxxxxxxxxxxx>

Pushed to drm-misc-fixes:

7aa83fbd712a drm/bridge: ti-sn65dsi86: Fix auxiliary bus lifetime