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 <pune...@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
+ 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>
--
1.7.1
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