On Thursday 09 February 2012 05:32 PM, Tomi Valkeinen wrote:

Hi,

On Thu, 2012-02-09 at 12:14 +0530, Archit Taneja wrote:

quoted

For DSS clock domain to transition from idle to active state, it's necessary
to enable the optional clock DSS_FCLK before we enable the module using the
MODULEMODE bits in the DSS clock domain's CM_DSS_DSS_CLKCTRL register.

This sequence was not followed correctly for the 'dss_hdmi' hwmod and it led
to DSS clock domain not getting out of idle when pm_runtime_get_sync() was
called for hdmi's platform device.

Since the clock domain failed to change it's state to active, the hwmod code
disables any clocks it had enabled before for this hwmod. This led to the clock
'dss_48mhz_clk' getting disabled.

When hdmi's runtime_resume() op is called, the call to dss_runtime_get()
correctly enables the DSS clock domain this time. But the clock 'dss_48mhz_clk'
disabled before is needed for HDMI's PHY to function. Hence, the driver fails

There's something wrong with the "But the clock..." sentence above.

The patch looks good, but I think it'd be better to add brief HACK
comments in the code also. Otherwise it's too easy to forget about this.

I'll make the changes and repost.

Archit

  Tomi