From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail11.truemail.it (mail11.truemail.it [217.194.8.81]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1BA132737EB; Fri, 6 Feb 2026 16:11:06 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.194.8.81 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770394268; cv=none; b=UwEKxXDlVQKLnWzBHoNaI9Aeq+hILMNFIE1mle71PiQ7YKF+VTa7eSErwaRbFqXdba6QYx/JIP+t8pMPVLlZ5hDxLNCjsOJmGnesflA6ANQwc2XnQaJpqsdvb+GlAwckNZpcYPca9YZweoXfOyiQpk/+Z8AIqFYNGphqkpiqTGo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770394268; c=relaxed/simple; bh=qWEoHxi5HN14Ce3uW+zwPyrQDcl0R5vhnLtErPfBQc0=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=fIju/w1vunPPAGoMA6IWUS41pV1y5gXlJjY56FtSmp2tAwgrBkEgXaQ5De3Ciqr2JowWT7rs+6h6CFbWf3GsbIKrMlwLUIgZ8j1fHpRKGW7Gn9PUmq089n0lyjlow1pcRKfUo+oj472P8xO8OoEzqKPMSEvVvfLBlPjaCKB2abc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=dolcini.it; spf=pass smtp.mailfrom=dolcini.it; dkim=pass (2048-bit key) header.d=dolcini.it header.i=@dolcini.it header.b=ou6udq04; arc=none smtp.client-ip=217.194.8.81 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=dolcini.it Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=dolcini.it Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=dolcini.it header.i=@dolcini.it header.b="ou6udq04" Received: from francesco-nb (93-49-2-63.ip317.fastwebnet.it [93.49.2.63]) by mail11.truemail.it (Postfix) with ESMTPA id 9A43B1FAA2; Fri, 6 Feb 2026 17:10:58 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=dolcini.it; s=default; t=1770394259; bh=NWmcPAurNjwlvM/3wgdAOFlyTkvK8iV82QRVbSW0Kyk=; h=From:To:Subject; b=ou6udq04170rew7KaDkpcdF0rIvdQ+e1HIu9Ue9zEq75DDwlLbBh5k+78OScUOLCs 3t2pw3vmrSXL0nMOoAzLDWMYW1lW46JOsjbRrvS6+E9AfLPUVpVU0XZD7sK2t/okpx oTUfzX/gVGsIrY3HLJmTxk0jPJ1bpPXM5A65nU6j2oAbjP+sjCgDgzSw7wANQeYuNd ThkCIxdDuAzN8x+dC2az9a4gS6ZBErejb15LxneO0SfAHJ4Ur8FAhHBiIeonMx9Wbj FPq+Usha/ZIQDFDaINGChO3m4Qq/cFliwdIuksjBts7qBAfZSiYIRAWaJSvF8Xb8GN 4NBWha2C10FJw== Date: Fri, 6 Feb 2026 17:10:54 +0100 From: Francesco Dolcini To: Doug Anderson Cc: Franz Schnyder , Andrzej Hajda , Neil Armstrong , Robert Foss , Laurent Pinchart , Jonas Karlman , Jernej Skrabec , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter , Franz Schnyder , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, Francesco Dolcini , stable@vger.kernel.org Subject: Re: [PATCH v1] drm/bridge: ti-sn65dsi86: Enable HPD polling if IRQ is not used Message-ID: <20260206161054.GA101724@francesco-nb> References: <20260206123758.374555-1-fra.schnyder@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: 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 wrote: > > > > From: Franz Schnyder > > > > 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: stable@vger.kernel.org > > Signed-off-by: Franz Schnyder > > --- > > 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: # 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? Thanks, Francesco