Hi Frank,
Em Thu, 8 Nov 2012 20:11:53 +0200
Frank Schäfer <fschaefer.oss@xxxxxxxxxxxxxx> escreveu:
> By default, isoc transfers are used if possible.
> With the new module parameter, bulk can be selected as the
> preferred USB transfer type.
I did some tests yesterday with prefer_bulk. IMHO, webcams should
select bulk mode by default, as this allows more than one camera to
work at the same time (I tested yesterday with 3 Silvercrest ones on
my notebook). With ISOC transfers, the core won't let it to happen, as
a single camera reserves 51% of the max allowed isoc traffic.
> Signed-off-by: Frank Schäfer <fschaefer.oss@xxxxxxxxxxxxxx>
> ---
> drivers/media/usb/em28xx/em28xx-cards.c | 11 +++++++++--
> 1 Datei geändert, 9 Zeilen hinzugefügt(+), 2 Zeilen entfernt(-)
>
> diff --git a/drivers/media/usb/em28xx/em28xx-cards.c b/drivers/media/usb/em28xx/em28xx-cards.c
> index a9344f0..7f5b303 100644
> --- a/drivers/media/usb/em28xx/em28xx-cards.c
> +++ b/drivers/media/usb/em28xx/em28xx-cards.c
> @@ -61,6 +61,11 @@ static unsigned int card[] = {[0 ... (EM28XX_MAXBOARDS - 1)] = UNSET };
> module_param_array(card, int, NULL, 0444);
> MODULE_PARM_DESC(card, "card type");
>
> +static unsigned int prefer_bulk;
> +module_param(prefer_bulk, int, 0644);
This needs to be changed to 0444, as prefer_bulk doesn't allow changing
it dynamically, as the test is done during device probe, not at stream on.
Regards,
Mauro
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