From mboxrd@z Thu Jan 1 00:00:00 1970 From: Olof Johansson Subject: Re: [PATCH v2] soc: qcom: do not disable the iface clock in probe Date: Tue, 23 Sep 2014 21:39:05 -0700 Message-ID: <20140924043905.GA24803@localhost> References: <1411500054-13600-1-git-send-email-srinivas.kandagatla@linaro.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mail-pd0-f181.google.com ([209.85.192.181]:62688 "EHLO mail-pd0-f181.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750826AbaIXFiX (ORCPT ); Wed, 24 Sep 2014 01:38:23 -0400 Received: by mail-pd0-f181.google.com with SMTP id r10so7690080pdi.26 for ; Tue, 23 Sep 2014 22:38:22 -0700 (PDT) Content-Disposition: inline In-Reply-To: <1411500054-13600-1-git-send-email-srinivas.kandagatla@linaro.org> Sender: linux-arm-msm-owner@vger.kernel.org List-Id: linux-arm-msm@vger.kernel.org To: Srinivas Kandagatla Cc: khilman@linaro.org, arm@kernel.org, agross@codeaurora.org, galak@codeaurora.org, linux-arm-kernel@lists.infradead.org, linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org On Tue, Sep 23, 2014 at 08:20:54PM +0100, Srinivas Kandagatla wrote: > since commit 31964ffebbb9 ("tty: serial: msm: Remove direct access to GSBI")' > serial hangs if earlyprintk are enabled. > > This hang is noticed only when the GSBI driver is probed and all the > earlyprintks before gsbi probe are seen on the console. > The reason why it hangs is because GSBI driver disables hclk in its > probe function without realizing that the serial IP might be in use by > a bootconsole. As gsbi driver disables the clock in probe the > bootconsole locks up. > > Turning off hclk's could be dangerous if there are system components > like earlyprintk using the hclk. > > This patch fixes the issue by delegating the clock management to > probe and remove functions in gsbi rather than disabling the clock in probe. > > More detailed problem description can be found here: > http://www.spinics.net/lists/linux-arm-msm/msg10589.html > > Tested-by: Linus Walleij > Signed-off-by: Srinivas Kandagatla > --- > Hi Kevin, > > Am resending this patch with reference to the problem and adding more > details to the log. > > Could you pick this fix for the next rc, as this fixes a serial console > hang with earlyprintk on SOCs like APQ8064. > > Changes since v1: > - added more info in the change log as requested by Kumar and Kevin. Applied to fixes. -Olof