Hi!
Hi Marek,
On Thursday 01 March 2012 02:59 AM, Marek Vasut wrote:
Add "CONFIG_USB_STRING_FETCH" to fetch first string descriptor length and then pass this length to fetch string descriptor.
Signed-off-by: Puneet Saxenapuneets@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_FETCHEnables settings to USB core to handle string issues whichfew 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
It does not avoid string fetch.
Well it does certainly not call usb_get_string()
I checked with few mass storage devices that they does not handle string descriptor request correctly and so we get start/stop Cache alignment error.
Cache alignment error ? Wow, how's that actually related to SUB string fetching? Maybe we should manually realign the result then? I still don't really understand what you're seeing, sorry ... can you please elaborate?
One way is, blacklist those devices by vendor id/product id.. etc. This is done in Linux kernel. Plz see Message.c (drivers\usb\core) Line: 722. Blacklisting the device requires a framework to detect the device...However this could be achieved simply with this implementation.
Sure, I see your intention, but I still don't get the problem, see above. Can you also tell me if there's particular device that's broken and which one is it (precise type etc)?
Thanks a lot for your cooperation on this matter!
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>