From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alexander Graf Date: Wed, 7 Mar 2018 14:40:29 +0100 Subject: [U-Boot] [PATCH 0/2] [for 2018.03] RPi: Drain RX queue on setbrg In-Reply-To: References: <20180306131327.61174-1-agraf@suse.de> Message-ID: <980b561e-12c5-0fb8-9566-e560eb3a35f1@suse.de> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de On 03/07/2018 02:07 PM, Peter Robinson wrote: > On Tue, Mar 6, 2018 at 1:13 PM, Alexander Graf wrote: >> We had a few reports coming in from people that had their autoboot chain >> aborted after pinmuxing support was added for the RPi. >> >> The culprit is easy: The UARTs may have been enabled before, but muxed >> to an incorrect pin. That pin may have pulled the RX line down which again >> lead to lots of zero bytes gathered in the RX buffer. >> >> The easy fix for that is to drain the RX queue every time we set the baud >> rate. >> >> This patch set is the minimally intrusive fix for the RPi. We may want to >> do that generically for all serial devices later. >> >> Alexander Graf (2): >> serial_bcm283x_mu: Flush RX queue after setting baud rate >> bcm283x_pl011: Flush RX queue after setting baud rate > This causes mixed effects for me, a regression on the RPi2 using the > pl011, but fixes the issue on the RPi3. Both my RPi2 have serial > console and playing with the enable in config.txt doesn't seem to have > any effect on whether they auto boot or not but with it commented out > I seem to get more random chars. Thanks a lot for testing! I'll try it on a rpi2 later tonight and check why it's failing. Alex