From mboxrd@z Thu Jan 1 00:00:00 1970 From: olof@lixom.net (Olof Johansson) Date: Tue, 23 Sep 2014 21:39:05 -0700 Subject: [PATCH v2] soc: qcom: do not disable the iface clock in probe In-Reply-To: <1411500054-13600-1-git-send-email-srinivas.kandagatla@linaro.org> References: <1411500054-13600-1-git-send-email-srinivas.kandagatla@linaro.org> Message-ID: <20140924043905.GA24803@localhost> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.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