From 33a783f353d9d01d4eaf57d32a1d09547440d0bf Mon Sep 17 00:00:00 2001 From: Antonio Ospite Date: Wed, 10 Jun 2015 11:05:46 +0200 Subject: [PATCH] am7xxx: improve the comment about setting a new configuration Explain better why it is not needed to detach all kernel drivers in most situations. --- src/am7xxx.c | 23 +++++++++++++++++------ 1 file changed, 17 insertions(+), 6 deletions(-) diff --git a/src/am7xxx.c b/src/am7xxx.c index 3ba56f3..b4e3e54 100644 --- a/src/am7xxx.c +++ b/src/am7xxx.c @@ -744,13 +744,24 @@ static int open_device(am7xxx_context *ctx, if (current_configuration != (*dev)->desc->configuration) { /* - * In principle kernel drivers bound to each interface should - * be detached before setting the configuration, but in - * practice this is not necessary for most devices. + * In principle, before setting a new configuration, kernel + * drivers should be detached from _all_ interfaces; for + * example calling something like the following "invented" + * function _before_ setting the new configuration: * - * For example something like the following function would be - * called: - * libusb_detach_all_kernel_drivers((*dev)->usb_device); + * libusb_detach_all_kernel_drivers((*dev)->usb_device); + * + * However, in practice, this is not necessary for most + * devices as they have only one configuration. + * + * When a device only has one configuration: + * + * - if there was a kernel driver bound to the device, it + * had already set the configuration and the call below + * will be skipped; + * + * - if no kernel driver was bound to the device, the call + * below will suceed. */ ret = libusb_set_configuration((*dev)->usb_device, (*dev)->desc->configuration); -- 2.1.4