[PATCH] Documentation: kernel-parameters.txt Add drm_kms_helper.poll

[Daniel Vetter]

On Thu, Oct 4, 2012 at 12:34 PM,  <mika.kuoppala at intel.com> wrote:
> From: Mika Kuoppala <mika.kuoppala at intel.com>
>
> Add description for drm_kms_helper.poll module parameter introduced
> by commit: e58f637bb96d5a0ae0919b9998b891d1ba7e47c9
>
> Signed-off-by: Mika Kuoppala <mika.kuoppala at intel.com>

Actually I've noticed even with just hdmi it stalls for long enough to
miss a frame, on an otherwise idle system. Kernel testcases ftw, kms
locking ftl :(

Reviewed-by: Daniel Vetter <daniel.vetter at ffwll.ch>

> ---
>  Documentation/kernel-parameters.txt |   11 +++++++++++
>  1 file changed, 11 insertions(+)
>
> diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
> index f777fa9..ad97749 100644
> --- a/Documentation/kernel-parameters.txt
> +++ b/Documentation/kernel-parameters.txt
> @@ -741,6 +741,17 @@ 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 VGA devices on older systems
> +                       can be quite expensive, causing latencies of
> +                       several hundred milliseconds. This will cause visible
> +                       stalls, for example in video playback. If you
> +                       experience stalls in display output occurring every
> +                       10 seconds (DRM_OUTPUT_POLL_PERIOD=(10*HZ)), disabling
> +                       polling might help.
> +                       Format: <bool>  (1/Y/y=enable, 0/N/n=disable)
> +                       default: enabled
> +
>         dscc4.setup=    [NET]
>
>         dyndbg[="val"]          [KNL,DYNAMIC_DEBUG]
> --
> 1.7.9.5
>
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch