From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paul Burton Subject: Re: [REGRESSION] "console: don't prefer first registered if DT specifies stdout-path" breaks console on video outputs of various ARM boards Date: Fri, 4 Nov 2016 12:30:35 +0000 Message-ID: <17833033.PtOSTzKXGD@np-p-burton> References: <20161104121135.4780-1-hdegoede@redhat.com> Mime-Version: 1.0 Content-Type: multipart/signed; boundary="nextPart10734688.zpdo6DTjzD"; micalg=pgp-sha256; protocol="application/pgp-signature" Return-path: In-Reply-To: <20161104121135.4780-1-hdegoede@redhat.com> Sender: linux-kernel-owner@vger.kernel.org To: Hans de Goede Cc: Linus Torvalds , Andrew Morton , Rob Herring , Frank Rowand , Thorsten Leemhuis , Greg Kroah-Hartman , Tejun Heo , devicetree@vger.kernel.org, linux-kernel@vger.kernel.org List-Id: devicetree@vger.kernel.org --nextPart10734688.zpdo6DTjzD Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" Hi Hans, On Friday, 4 November 2016 13:11:34 GMT Hans de Goede wrote: > Hi All, > > While booting 4.9-rc# for the first time on an Allwinner A33 tablet, > I noticed that after u-boot the LCD display stayed black. It turns out > that there was an issue which caused X to never get up, and all kernel > (and other startup) messages prior to that only went to ttyS0 which > consists of 2 tiny testpads on the PCB with this tablet. > > The same issue will also happen on any ARM boards which have a HDMI or > composite video output and which use a stdout-path pointing to their > serial console. I think this will e.g. also impact the Raspberry Pi, > I know for certain that this will impact the 99 different Allwinnner > boards currently supported by mainline u-boot + the mainline kernel. > > This is a behavior changes from previous kernels and I consider this > a regression. Thus I propose to revert the commit in question, for more > info here is a partial copy of the commit message of the proposed revert: > > The reverted commit changes existing behavior on which many ARM boards > rely. Many ARM small-board-computers, like e.g. the Raspberry Pi have > both a video output and a serial console. Depending on whether the user > is using the device as a more regular computer; or as a headless device > we need to have the console on either one or the other. > > Many users rely on the kernel behavior of the console being present on > both outputs, before the reverted commit the console setup with no > console= kernel arguments on an ARM board which sets stdout-path in dt > would look like this: > > [root@localhost ~]# cat /proc/consoles > ttyS0 -W- (EC p a) 4:64 > tty0 -WU (E p ) 4:1 > > Where as after the reverted commit, it looks like this: > > [root@localhost ~]# cat /proc/consoles > ttyS0 -W- (EC p a) 4:64 > > This commit reverts commit 05fd007e4629 ("console: don't prefer first > registered if DT specifies stdout-path") restoring the original behavior. > > Regards, > > Hans Ugh... so the devices you're talking about rely upon set stdout-path in their device tree but effectively rely upon us ignoring it? If that's the case then I guess reverting is probably the best option, but it does restore us to a position where we honor stdout-path for earlycon & then essentially ignore it for the proper kernel console. That seems pretty bust to me... Thanks, Paul --nextPart10734688.zpdo6DTjzD Content-Type: application/pgp-signature; name="signature.asc" Content-Description: This is a digitally signed message part. Content-Transfer-Encoding: 7Bit -----BEGIN PGP SIGNATURE----- iQIcBAABCAAGBQJYHH9rAAoJEIIg2fppPBxl34sP/3eBsFz+Py27TY9MTC8SrgVA Qz0ci+m/noH44R17XPQpIxS5xegN52A3VfL2yL/L/iPkX8eWW5btFumNusqgHlUS wlFoAJDCUNNjdEYGZx4BIuTqDRcHl7MF2VXKo0dgTeoqO9+ayxYUrnzdX8xLKSlK A/xL5MUeADF5iUzbuAxUrYBtvNRm6QB+KwQN6nwOe/9ichxINgp9+J7beFBhvtzM Fg0U3kgFubSpkB2AKLly4gAXLNbGE13KWPa9SIpOzJZnr2EqAX5pQFZCZtSOTDyY CTs5orsTDuT7hKqtLQjD21mtrF9Oan9D6JhuUd9HLz+6a9RTwiuWffMe/nTZ8UMU +zABhTiQrfEhwOpjWYzIRMSCK5RlKEvkvP7Fa2f2j4HPD4yBmHem7bIUIE0sjkgu 1Ke/f6mfNTaBx1XFoY4xtsixS/0C4RemXlLBG7I8YThsvusI/0QrtRiCVHiMPr45 RlbuXIZAu/sXG0zRJGLCFxpS2Cl5jsKmpvYTGPlTFuQV025eCwPtM1EwsIjKVRS4 vb90X9WgoZDkzVkWc4H3IGRMquE5AZQ62i/9EtnpoVYSm4oMD6a70qSiGEx7zmLI 32lSnkoBel3IKVvX13bXr7ImhedKz3oB1QVRlfK5+1Rz2dyzE2NO0STBCt7cq+q5 HbG0b0F1Yu8mboxlVcMz =+W3i -----END PGP SIGNATURE----- --nextPart10734688.zpdo6DTjzD--