Re: [PATCH 2/2] OMAPDSS: APPLY: make ovl_enable/disable synchronous

On Wed, Feb 29, 2012 at 4:48 AM, Florian Tobias Schandinat
[off-list ref] wrote:

Hi Tomi,

On 02/29/2012 10:30 AM, Tomi Valkeinen wrote:

quoted

On Wed, 2012-02-29 at 10:13 +0000, Florian Tobias Schandinat wrote:

quoted

On 02/29/2012 08:48 AM, Tomi Valkeinen wrote:

quoted

ovl->enable/disable are meant to be synchronous so that they can handle
the configuration of fifo sizes. The current kernel doesn't configure
fifo sizes yet, and so the code doesn't need to block to function (from
omapdss driver's perspective).

However, for the users of omapdss a non-blocking ovl->disable is
confusing, because they don't know when the memory area is not used
any more.

Furthermore, when the fifo size configuration is added in the next merge
window, the change from non-blocking to blocking could cause side
effects to the users of omapdss. So by making the functions block
already will keep them behaving in the same manner.

Is there any difference to doing it now?
I agree that this should be fixed but if we can't avoid breaking users I'd
prefer to break them in a merge window not in late rc stage. Or did we introduce
these functions just in the last merge window?

Yes, these were introduced in the merge window. And I explicitly said
the functions are blocking so that they can perform their job. And just
to clarify, the functions already use a mutex, so in that sense they are
blocking. They just don't currently wait until the HW has finished with
the overlay.

okay, than I'll apply this patch as is. I was just worried about asking Linus to
pull something that is labled as "Breaks existing users" now, but that doesn't
look like an issue here.

I don't expect this change should break any existing users.. I think
it is safe to call this a bug fix

BR,
-R

Best regards,

Florian Tobias Schandinat

quoted

The problem was raised by Rob Clark, who's writing the omapdrm driver,
as he doesn't have a way to ensure that the overlay has been truly
disabled and the memory is is no longer in use.

(I forgot to cc him for the patch, adding him now).

 Tomi

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