From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 391F417A2F6; Sun, 8 Mar 2026 09:47:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772963255; cv=none; b=M3pMuV3rIR04INR5ppzACSf0AdbQ8Xt/RMmCmlop0iY1OhnZ8F3NkLWWYJ6AT3vyfNf7W3GmjzhPigSMuV1tSyXlLZZWcGanWjLzWrpxa4nCUVLvlCEwYI0l6rGqoxqIFYHfBG2inTLf3LqbvuWeC50FmBOqw74lSKadPUpZo2I= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772963255; c=relaxed/simple; bh=PJ/9tu4qNJoagggBdPlz3TTFrsJFAYDkXxreRvZYzbc=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=uvROFIsAiPSLn3jS6g5pFVkxrPp1clqfi30KyrreArF6f+IZYZIi/ZicrC7oybQijep6aTdn1NTzLz77Hi/Tnbzlugdm+oD4So8Y/2//ST6hqmrKKzI19jyH8Be7vpibKbiexE0hR/Mus1PTDiAAOxiFbXOOwf/jtH9wgUpFjlY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=inkuBTNQ; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="inkuBTNQ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 64498C116C6; Sun, 8 Mar 2026 09:47:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1772963254; bh=PJ/9tu4qNJoagggBdPlz3TTFrsJFAYDkXxreRvZYzbc=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=inkuBTNQQQ2/C91px9u6cd8g6uvQtqjOLZrbOBsE11CrW/uQaL2p2G9DhEE7iHZJ1 1rj2EA7lUYmYzlvnkhv47/WMkBIzIjyoqoihhn36HfNTOmoxJEMywf22x5OJXJL+dT 3U9ZzDQRV5O32oYL9U5AI791+YbkbSv/lScJ1WMY= Date: Sun, 8 Mar 2026 10:47:20 +0100 From: Greg KH To: hgfdgjn Cc: stable@vger.kernel.org, regressions@lists.linux.dev Subject: Re: [BUG] HDMI monitor shows no signal when the refresh rate is higher than the default 60Hz Message-ID: <2026030839-applied-prominent-b774@gregkh> References: Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Sun, Mar 08, 2026 at 05:42:39PM +0800, hgfdgjn wrote: > Hi maintainers: > > After updating to v6.19.6 on Arch Linux, if I set the refresh rate > higher than 60Hz, the monitor displays "No Signal". > I tried bisecting and found: > > # first bad commit: [3471b9a31ce352ffb343cf02a991261880aac3a7] drm/amd/display: Rework HDMI data channel reads > > This issue on my machine was caused by this change: > > diff --git a/drivers/gpu/drm/amd/display/dc/link/protocols/link_ddc.c > b/drivers/gpu/drm/amd/display/dc/link/protocols/link_ddc.c > index 267180e7bc48..5d2bcce2f669 100644 > --- a/drivers/gpu/drm/amd/display/dc/link/protocols/link_ddc.c > +++ b/drivers/gpu/drm/amd/display/dc/link/protocols/link_ddc.c > @@ -549,7 +549,8 @@ void write_scdc_data(struct ddc_service *ddc_service, > /*Lower than 340 Scramble bit from SCDC caps*/ > > if (ddc_service->link->local_sink && > - ddc_service->link->local_sink->edid_caps.panel_patch.skip_scdc_overwrite) > + (ddc_service->link->local_sink->edid_caps.panel_patch.skip_scdc_overwrite > || > + !ddc_service->link->local_sink->edid_caps.scdc_present)) > return; > > link_query_ddc_data(ddc_service, slave_address, &offset, > > > It appears that scdc_present is always false on my device. > I reverted the change to write_scdc_data(), and the monitor works > normally at high refresh rates. Can you cc: the developers and maintainers of this change to let them know? Otherwise they will not notice it. Also, does 7.0-rc2 show this issue? thanks, greg k-h