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Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92 #3 (Red Hat Linux)) id 1hgWXN-0007t8-FX; Thu, 27 Jun 2019 15:42:13 +0000 Received: from relay7-d.mail.gandi.net ([217.70.183.200]) by bombadil.infradead.org with esmtps (Exim 4.92 #3 (Red Hat Linux)) id 1hgWTJ-0002b2-E6 for linux-arm-kernel@lists.infradead.org; Thu, 27 Jun 2019 15:38:04 +0000 X-Originating-IP: 92.137.69.152 Received: from localhost (alyon-656-1-672-152.w92-137.abo.wanadoo.fr [92.137.69.152]) (Authenticated sender: gregory.clement@bootlin.com) by relay7-d.mail.gandi.net (Postfix) with ESMTPSA id D9B4720007; Thu, 27 Jun 2019 15:37:47 +0000 (UTC) From: Gregory CLEMENT To: Joshua Scott , linux-arm-kernel@lists.infradead.org, Jason Cooper , Andrew Lunn , Sebastian Hesselbarth Subject: Re: [PATCH v3] ARM: dts: armada-xp-98dx3236: Switch to armada-38x-uart serial node In-Reply-To: <20190625221108.21455-1-joshua.scott@alliedtelesis.co.nz> References: <20190625221108.21455-1-joshua.scott@alliedtelesis.co.nz> Date: Thu, 27 Jun 2019 17:37:47 +0200 Message-ID: <87sgrvghtg.fsf@FE-laptop> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190627_083801_678349_74ED43A9 X-CRM114-Status: GOOD ( 21.78 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Joshua Scott , stable@vger.kernel.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org Joshua Scott writes: > Switch to the "marvell,armada-38x-uart" driver variant to empty > the UART buffer before writing to the UART_LCR register. > > Signed-off-by: Joshua Scott > Tested-by: Andrew Lunn > Acked-by: Gregory CLEMENT . > Cc: stable@vger.kernel.org > Fixes: 43e28ba87708 ("ARM: dts: Use armada-370-xp as a base for > armada-xp-98dx3236") Applied on mvebu/fixes Thanks, Gregory > > --- > Changes in v3: > > Updated title, added tested-by, and Fixes tag > > Changes in v2: > > Andrew Lunn was able to test on a Marvell 370RD reference design, and > the character loss issue did not occur. > > The fix has now been changed to only affect the following SOCs: > * 98DX323x > * 98DX3333 > * 98DX4251 > > v1 message: > > We have found that like the armada 38x, other Marvell SOCs can lose > characters when the UART_LCR register is written to without first > waiting for the buffer to empty. > > We have observed this behaviour on the following Marvell switch SOCs: > > * 98DX323x > * 98DX3333 > * 98DX4251 > > However, we do not currently have access to non-switch SOCs which share > the same parent device-tree. > > The question we have is, should the fix be applied to the common > armada-370-xp device-tree, or should it be restricted to only affect the > SOCs listed above. > > If anybody is able to check, we would like to find out if the issue > affects other armada-xp / armada-370 based SOCs. > > The issue can be reproduced, if logging in using the serial port, with: > resize && echo "hello world" > > On affected devices, the first couple letters of "hello world" are > lost. On some SOCs this can be seen at 115200 baud, and on others > we have had to slow down to 9600 to see the issue. > > Cheers, > Joshua Scott > --- > arch/arm/boot/dts/armada-xp-98dx3236.dtsi | 8 ++++++++ > 1 file changed, 8 insertions(+) > > diff --git a/arch/arm/boot/dts/armada-xp-98dx3236.dtsi b/arch/arm/boot/dts/armada-xp-98dx3236.dtsi > index 59753470cd34..267d0c178e55 100644 > --- a/arch/arm/boot/dts/armada-xp-98dx3236.dtsi > +++ b/arch/arm/boot/dts/armada-xp-98dx3236.dtsi > @@ -336,3 +336,11 @@ > status = "disabled"; > }; > > +&uart0 { > + compatible = "marvell,armada-38x-uart"; > +}; > + > +&uart1 { > + compatible = "marvell,armada-38x-uart"; > +}; > + > -- > 2.21.0 > -- Gregory Clement, Bootlin Embedded Linux and Kernel engineering http://bootlin.com _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel