[xserver] modesetting: Consume all available udev events at once

[Hans de Goede]

Hi,

On 12/11/2015 01:05 PM, Daniel Martin wrote:
> From: Daniel Martin <consume.noise at gmail.com>
>
> We get multiple udev events for actions like docking a laptop into its
> station or plugging a monitor to the station. By consuming as much
> events as we can, we reduce the number of output re-evalutions.
>
> I.e. having a Lenovo X250 in a ThinkPad Ultra Dock and plugging a
> monitor to the station generates 5 udev events. Or having 2 monitors
> attached to the station and docking the laptop generates 7 events.
>
> It depends on the timing how many events can consumed at once.
>
> Signed-off-by: Daniel Martin <consume.noise at gmail.com>

Thank you for the patch one small comment below.

> ---
>  hw/xfree86/drivers/modesetting/drmmode_display.c | 13 +++++++------
>  1 file changed, 7 insertions(+), 6 deletions(-)
>
> diff --git a/hw/xfree86/drivers/modesetting/drmmode_display.c b/hw/xfree86/drivers/modesetting/drmmode_display.c
> index 0d34ca1..eeccb82 100644
> --- a/hw/xfree86/drivers/modesetting/drmmode_display.c
> +++ b/hw/xfree86/drivers/modesetting/drmmode_display.c
> @@ -1944,16 +1944,19 @@ drmmode_handle_uevents(int fd, void *closure)
>      drmModeResPtr mode_res;
>      xf86CrtcConfigPtr  config = XF86_CRTC_CONFIG_PTR(scrn);
>      int i, j;
> -    Bool found;
> +    Bool found = FALSE;
>      Bool changed = FALSE;
>
> -    dev = udev_monitor_receive_device(drmmode->uevent_monitor);
> -    if (!dev)
> +    while ((dev = udev_monitor_receive_device(drmmode->uevent_monitor))) {
> +        udev_device_unref(dev);
> +        found = TRUE;
> +    }
> +    if (!found)
>          return;
>
>      mode_res = drmModeGetResources(drmmode->fd);
>      if (!mode_res)
> -        goto out;
> +        return;

This change means that you're now no longer calling RRGetInfo() in this exit
path, which seems like an unrelated change.

I've applied this patch to my tree with this bit ommitted; and I will include
it in the pull-req with fixes for 1.19 I'm working on.



>      if (mode_res->count_crtcs != config->num_crtc) {
>          ErrorF("number of CRTCs changed - failed to handle, %d vs %d\n", mode_res->count_crtcs, config->num_crtc);
> @@ -2012,9 +2015,7 @@ drmmode_handle_uevents(int fd, void *closure)
>
>  out_free_res:
>      drmModeFreeResources(mode_res);
> -out:
>      RRGetInfo(xf86ScrnToScreen(scrn), TRUE);
> -    udev_device_unref(dev);
>  }
>  #endif
>
>

Regards,

Hans