Hi,
On Fri, Feb 6, 2026 at 8:27 AM Doug Anderson <[email protected]> wrote:
>
> Hi,
>
> On Fri, Feb 6, 2026 at 8:11 AM Francesco Dolcini <[email protected]> wrote:
> >
> > Hello Doug,
> >
> > On Fri, Feb 06, 2026 at 07:46:10AM -0800, Doug Anderson wrote:
> > > On Fri, Feb 6, 2026 at 4:38 AM Franz Schnyder <[email protected]>
> > > wrote:
> > > >
> > > > From: Franz Schnyder <[email protected]>
> > > >
> > > > Fallback to polling to detect hotplug events on systems without
> > > > interrupts.
> > > >
> > > > On systems where the interrupt line of the bridge is not connected,
> > > > the bridge cannot notify hotplug events. Only add the
> > > > DRM_BRIDGE_OP_HPD flag if an interrupt has been registered
> > > > otherwise remain in polling mode.
> > > >
> > > > Fixes: 9133bc3f0564 ("drm/bridge: ti-sn65dsi86: Add support for
> > > > DisplayPort mode with HPD")
> > > > Fixes: 55e8ff842051 ("drm/bridge: ti-sn65dsi86: Add HPD for DisplayPort
> > > > connector type")
> > > > Cc: [email protected]
> > > > Signed-off-by: Franz Schnyder <[email protected]>
> > > > ---
> > > > drivers/gpu/drm/bridge/ti-sn65dsi86.c | 6 ++++--
> > > > 1 file changed, 4 insertions(+), 2 deletions(-)
> > >
> > > It's weird that you have two fixes, but upon closer inspection, I see
> > > why you tagged it as you did.
> > >
> > > The first commit that landed, commit 55e8ff842051 ("drm/bridge:
> > > ti-sn65dsi86: Add HPD for DisplayPort connector type"), was still
> > > using polling mode and just using the HPD line for polling. That
> > > commit incorrectly set the flag "DRM_BRIDGE_OP_HPD". So the proper
> > > backport to kernels with just that commit would be to take away that
> > > flag. Unfortunately, I didn't notice this problem during the review
> > > and I don't personally have any hardware using this bridge for DP,
> > > only eDP.
> > >
> > > The second commit that landed, commit 9133bc3f0564 ("drm/bridge:
> > > ti-sn65dsi86: Add support for DisplayPort mode with HPD"), actually
> > > added support for the HPD interrupt. After this commit, your fix
> > > (which makes the flag "DRM_BRIDGE_OP_HPD" depend on the IRQ) is the
> > > correct one.
> > >
> > > Unfortunately, I think the above will confuse the stable scripts.
> > > Since your patch applied cleanly atop the first commit then it will
> > > picked to any kernels with it, even if they don't have the second
> > > commit.
> > >
> > > I think the first commit landed in v6.16 and the second commit isn't
> > > yet in any stable release.
> > >
> > > Maybe the right way to look at this is to just call the 2nd patch a
> > > prereq? So this:
> > >
> > > Fixes: 55e8ff842051 ("drm/bridge: ti-sn65dsi86: Add HPD for
> > > DisplayPort connector type")
> > > Cc: <[email protected]> # 6.16: 9133bc3f0564: drm/bridge:
> > > ti-sn65dsi86: Add
> > >
> > > That will cause the 2nd patch to get picked up for stable too, but
> > > that would be preferable to having just your fix without the 2nd
> > > patch. Alternatively, you could try to add some other note to the
> > > stable team to help them arrive at the right backport.
> >
> > We had some internal review before sending this patch and I am the one
> > that suggested to put both commit as fixes in the end.
> >
> > I agree that your solution is the correct one (I am not familiar with
> > the syntax there, but I agree on the concept), assuming
> > nobody disagree on this, should we send a v2, or are you going to amend
> > the commit message when applying it?
>
> You can see the docs at:
>
> Documentation/process/stable-kernel-rules.rst
>
> As long as you agree with what I came up with, there's no need for you
> to resend and I can adjust it when I land the patch. I'll still let it
> sit on the list for at least next week to give others a chance to
> review / comment.
Pushed to drm-misc-fixes with the updated Fixes / stable line.
[1/1] drm/bridge: ti-sn65dsi86: Enable HPD polling if IRQ is not used
commit: 0b87d51690dd5131cbe9fbd23746b037aab89815
