[PATCH] USB: core: Choose configuration with lowest bConfigurationValue
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From: Michal Nazarewicz on 22 Jul 2010 10:10 This patch removes code from usb_choose_configuration() responsible for ignoring the first USB device configuration if its first interface is RNDIS. Instead, usb_choose_configuration() chooses configuration with lowest bConfigurationValue. Linux' Ethernet gadget uses a lower bConfigurationValue for the second configuration which is a CDC configuration so this code should choose configuration that suits Linux better. Signed-off-by: Michal Nazarewicz <m.nazarewicz(a)samsung.com> --- Just what I had in mind if anyone interested... Not that I have any strong opinion about it. Also, not tested. drivers/usb/core/generic.c | 47 +++++++++++++++++++++---------------------- 1 files changed, 23 insertions(+), 24 deletions(-) diff --git a/drivers/usb/core/generic.c b/drivers/usb/core/generic.c index 9a34ccb..5b411af 100644 --- a/drivers/usb/core/generic.c +++ b/drivers/usb/core/generic.c @@ -46,6 +46,7 @@ int usb_choose_configuration(struct usb_device *udev) int num_configs; int insufficient_power = 0; struct usb_host_config *c, *best; + int best_is_not_class = 1; best = NULL; c = udev->config; @@ -102,33 +103,31 @@ int usb_choose_configuration(struct usb_device *udev) continue; } - /* When the first config's first interface is one of Microsoft's - * pet nonstandard Ethernet-over-USB protocols, ignore it unless - * this kernel has enabled the necessary host side driver. - */ - if (i == 0 && desc && (is_rndis(desc) || is_activesync(desc))) { -#if !defined(CONFIG_USB_NET_RNDIS_HOST) && !defined(CONFIG_USB_NET_RNDIS_HOST_MODULE) + /* From the remaining configs, choose one whose first + * interface is for a non-vendor-specific class and + * has lowest bConfigurationValue. Reason for the + * former: Linux is more likely to have a class driver + * than a vendor-specific driver. Reason for the + * latter: Ethernet gadget use lower + * bConfigurationValue for configuration with CDC ECM + * which is preferred by Linux even though it's second + * configuration. */ + if (udev->descriptor.bDeviceClass != + USB_CLASS_VENDOR_SPEC && + (desc && desc->bInterfaceClass != + USB_CLASS_VENDOR_SPEC)) { + if (best_is_not_class || + c->desc.bConfigurationValue < + best->desc.bConfigurationValue) { + best_is_not_class = 0; + best = c; + } continue; -#else - best = c; -#endif - } - - /* From the remaining configs, choose the first one whose - * first interface is for a non-vendor-specific class. - * Reason: Linux is more likely to have a class driver - * than a vendor-specific driver. */ - else if (udev->descriptor.bDeviceClass != - USB_CLASS_VENDOR_SPEC && - (desc && desc->bInterfaceClass != - USB_CLASS_VENDOR_SPEC)) { - best = c; - break; } /* If all the remaining configs are vendor-specific, * choose the first one. */ - else if (!best) + if (!best) best = c; } -- 1.7.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |