From mboxrd@z Thu Jan 1 00:00:00 1970 From: Darren Hart Subject: Re: [PATCH] pch_uart: Change default UART clock setting 192MHz Date: Tue, 21 Feb 2012 16:20:52 -0800 Message-ID: <4F4434E4.7040703@linux.intel.com> References: <1329800140-4279-1-git-send-email-tomoya.rohm@gmail.com> <4F43C15D.6080401@linux.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-2022-JP Content-Transfer-Encoding: 7bit Return-path: Received: from mga09.intel.com ([134.134.136.24]:50674 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752631Ab2BVAVh (ORCPT ); Tue, 21 Feb 2012 19:21:37 -0500 In-Reply-To: Sender: linux-serial-owner@vger.kernel.org List-Id: linux-serial@vger.kernel.org To: Tomoya MORINAGA Cc: Alan Cox , Greg Kroah-Hartman , linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org, qi.wang@intel.com, yong.y.wang@intel.com, joel.clark@intel.com, kok.howg.ewe@intel.com, feng.tang@intel.com On 02/21/2012 03:43 PM, Tomoya MORINAGA wrote: > 2012年2月22日1:07 Darren Hart : >> When does the phub driver update the clock registers? > > I've already posted pch_phub patch for 192MHz setting. > You can see the patch form below. Yes, I applied the patch. The problem seems to be this: DVHART: parse_options (8250_early.c) DVHART: pch_console_setup DVHART: pch_console_setup DVHART: pch_phub_probe: set CLKCFG UART to 192MHz As you can see, the pch_phub_probe happens much too late. I can get it to work with a boot command line like this: earlycon=uart8250,io,0x2050,115200n8 console=ttyPCH1,115200n8 And hacking all the BASE_BAUD references to be 48000000 (my current hardware sets the clock to 48MHz in firmware). This gets things working until pch_phub gets around to setting the CLKCFG register for the UART clock. I'd prefer to not have to use the earlycon parameter/code, but we need a way for the pch_uart to understand the difference between early boot and post-phub setup. Can we read the CLKCFG register in pch_console_setup to dynamically configure the port->uartclk? (not sure that's even the right place to do it). -- Darren >>> Signed-off-by: Tomoya MORINAGA >>> --- >>> Related patch is >>> http://marc.info/?l=linux-kernel&m=132979974907774&w=2 > > --- > ROHM Co., Ltd. > tomoya -- Darren Hart Intel Open Source Technology Center Yocto Project - Linux Kernel