From: Mika Kuoppala mika.kuoppala@intel.com

Possibility to disable polling to find connected displays was introduced by commit [1]:

commit e58f637bb96d5a0ae0919b9998b891d1ba7e47c9 Author: Chris Wilson chris@chris-wilson.co.uk Date: Fri Aug 20 09:13:36 2010 +0100

drm/kms: Add a module parameter to disable polling

Add description for this parameter to kernel-parameters.txt

[1] http://git.kernel.org/?p=linux/kernel/git/torvalds/linux.git;a=commit;h=e58f...

Signed-off-by: Mika Kuoppala mika.kuoppala@intel.com --- Documentation/kernel-parameters.txt | 16 ++++++++++++++++ 1 file changed, 16 insertions(+)

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index f777fa9..0f0f071 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -741,6 +741,22 @@ bytes respectively. Such letter suffixes can also be entirely omitted. if its name and a colon are prepended to the EDID name.

+ drm_kms_helper.poll= + Polling for connected display devices on older systems + without Hot Plug Detect (HPD) support, can be quite + expensive. Poll will happen periodically and can in + worst cases take several hundred milliseconds, + depending on the hardware. This will cause visible + stalls, for example in video playback. These stalls + might happen even when your video is on HDP output + but you have other non HDP outputs in your hw + configuration. If you experience stalls in display + output occurring every 10 seconds, disabling polling + might help. With polling disabled you need to manually + use xrandr to trigger detection. + Format: <bool> (1/Y/y=enable, 0/N/n=disable) + default: enabled + dscc4.setup= [NET]

dyndbg[="val"] [KNL,DYNAMIC_DEBUG]