Re: [PATCH] OMAPDSS: Check if RPM enabled before trying to change state

On 25 June 2012 15:00, Tomi Valkeinen [off-list ref] wrote:

On Mon, 2012-06-25 at 14:19 +0530, Jassi Brar wrote:

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On 25 June 2012 11:50, Tomi Valkeinen [off-list ref] wrote:

quoted

On Sat, 2012-06-23 at 13:36 +0530, jaswinder.singh@linaro.org wrote:

....

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 Currenlty HDMI fails to come up in the suspend-resume path.
This patch helps that real-world scenario.

What is the problem there? It'd be good to explain the problem in the
patch description. Does the pm_runtime_get return -EACCES?

Yes, it returns -EACCESS because RPM on devices is disabled during the
period from suspend-start to resume-finished.

So... You didn't answer my first comment, how can the code work?

Sorry, don't know why I thought I didn't miss anything.

The driver needs to enable the HW and the call to pm_runtime_get() is
skipped. Won't this lead to crash as the DSS registers are accessed
without the HW in enabled state?

Hmm...  how does the extant code in hdmi driver ensures DSS is up and running ?
While it does sound important even to my limited knowledge of OMAPDSS,
I see rpm of HDMI, VENC and RFBI only dependent on DISPC, not DSS.

And for DISPC these drivers already hold a reference in their display
enable/resume and keep it until disable/suspend. So we don't lose
DISPC anytime it is really required.

And what happens if the pm_runtime_get() call is skipped, but pm_runtime_put() is not?

Not sure in what newly introduced scenario by this patch, because
get/put both check for pm_enabled before proceeding. Am I overlooking
something?

thnx