am7xxx: improve the comment about setting a new configuration

Explain better why it is not needed to detach all kernel drivers in most
situations.

diff --git a/src/am7xxx.c b/src/am7xxx.c
index 3ba56f3..b4e3e54 100644 (file)
--- 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);