[U-Boot] [PATCH v3 2/2] usb: Add CONFIG to fetch string descriptor

Marek Vasut
2012-02-29T21:29:00Z

> Add "CONFIG_USB_STRING_FETCH" to fetch first string descriptor length
> and then pass this length to fetch string descriptor.
>
> Signed-off-by: Puneet Saxena <puneets@nvidia.com>
> ---
>
> Changes for V2:
> - Change existing config by "CONFIG_USB_STRING_FETCH"
>
> Changes for V3:
> - Removed extra new line
> - Explained "CONFIG_USB_STRING_FETCH" in top level README
>
> README | 4 ++++
> common/usb.c | 4 ++++
> include/configs/tegra2-common.h | 2 ++
> 3 files changed, 10 insertions(+), 0 deletions(-)
>
> diff --git a/README b/README
> index 7adf7c7..c045a37 100644
> --- a/README
> +++ b/README
> @@ -1138,6 +1138,10 @@ The following options need to be configured:
> CONFIG_USB_EHCI_TXFIFO_THRESH enables setting of the
> txfilltuning field in the EHCI controller on reset.
>
> + CONFIG_USB_STRING_FETCH
> + Enables settings to USB core to handle string issues which
> + few devices can not handle.
> +
> - USB Device:
> Define the below if you wish to use the USB console.
> Once firmware is rebuilt from a serial console issue the
> diff --git a/common/usb.c b/common/usb.c
> index 191bc5b..a73cb60 100644
> --- a/common/usb.c
> +++ b/common/usb.c
> @@ -658,9 +658,13 @@ static int usb_string_sub(struct usb_device *dev,
> unsigned int langid, {
> int rc;
>
> +#ifdef CONFIG_USB_STRING_FETCH

Shouldn't this be something like ... CONFIG_USB_AVOID_STRING_FETCH then?

Anyway, how come some devices can't handle it? What happens then? What devices
are those (exact type etc)?

I believe the bug is deeper and adding extra config options can be avoided, what
do you think?

Thanks!

M

> + rc = -1;
> +#else
> /* Try to read the string descriptor by asking for the maximum
> * possible number of bytes */
> rc = usb_get_string(dev, langid, index, buf, 255);
> +#endif
>
> /* If that failed try to read the descriptor length, then
> * ask for just that many bytes */
> diff --git a/include/configs/tegra2-common.h
> b/include/configs/tegra2-common.h index 266d0e5..d20b49c 100644
> --- a/include/configs/tegra2-common.h
> +++ b/include/configs/tegra2-common.h
> @@ -93,6 +93,8 @@
> #define CONFIG_USB_EHCI_TXFIFO_THRESH 10
> #define CONFIG_EHCI_IS_TDI
> #define CONFIG_EHCI_DCACHE
> +/* string descriptors must not be fetched using a 255-byte read */
> +#define CONFIG_USB_STRING_FETCH
>
> /* include default commands */
> #include <config_cmd_default.h>