From mboxrd@z Thu Jan 1 00:00:00 1970 From: Michal Simek Subject: Re: [RFC. PATCH] earlycon: Remove hardcoded port->uartclk initialization in of_setup_earlycon Date: Mon, 23 Apr 2018 15:22:51 +0200 Message-ID: <18997e5d-dcbf-3a99-e1db-994ba97b1e24@xilinx.com> References: <6626f66e-e1a6-9e54-0011-95ab4949bd3b@mips.com> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <6626f66e-e1a6-9e54-0011-95ab4949bd3b@mips.com> Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org To: Matt Redfearn , Michal Simek , linux-kernel@vger.kernel.org, monstr@monstr.eu, devicetree@vger.kernel.org, Rob Herring Cc: Greg Kroah-Hartman , linux-serial@vger.kernel.org, Jiri Slaby List-Id: linux-serial@vger.kernel.org Hi, On 23.4.2018 15:16, Matt Redfearn wrote: > > > On 23/04/18 10:27, Michal Simek wrote: >> There is no reason to initialize uartclk to BASE_BAUD * 16 for DT based >> systems. >> >> Signed-off-by: Michal Simek >> --- >> >> It looks like from history that portclk = BASE_BAUD * 16 was setup to >> get on calculation on x86 (divisor = 1) but it shouldn't be needed on >> DT based >> system. That's why I think that there is no DT based system which really >> requires this line. > > Hi Michal, > > This is fine for the MIPS generic platform (tested on Boston board) > which was broken by some earlycon changes a few versions ago. Also > tested on a MIPS pistachio board. As long as the bootloader has > configured the uart divisor, earlycon should work as long as my patch > "serial: 8250_early: Only set divisor if valid clk & baud" is applied to > avoid a bad divisor getting calculated. I have sent one patch to fix your patch because you don't need to check device->baud twice. [PATCH] serial: 8250_early: Setup divider when uartclk is passed > Tested-by: Matt Redfearn Thanks, Michal