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 <redacted>
Signed-off-by: Srinivas Kandagatla <redacted>
---
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