Hi Marek,
On Monday 05 March 2012 06:18 PM, Marek Vasut wrote:
Dear Puneet Saxena,
Hi Marek,
On Thursday 01 March 2012 05:15 PM, Marek Vasut wrote:
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 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
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()
Precisely, it avoids fetching string desc of 255 bytes. so better name
could be
"CONFIG_USB_AVOID_STRING_FETCH_255". Thanks for your comment.
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?
The particular mass storage device is -
Vendor: Kingston Rev: PMAP Prod: DataTraveler 2.0
Type: Removable Hard Disk
Capacity: 1906.0 MB = 1.8 GB (3903488 x 512)
When code tries to read Manufacturing Id..prod id...etc..it passes cache
aligned buffer "tbuf" in
"usb_string()" @usb.c. Inside "usb_string_sub()", usb_get_string()
passes as default 255 bytes to fetch string
descriptor.
The code in "ehci_submit_async() " invalidates *partially* the passed
buffer though we pass aligned buffer and "STD_ASS"
is received. Though it should invalidate only the cached line which is
equal(~32) to string desc length.
Hm ... so this means the bug is in ehci_hcd? Maybe the ehci_hcd should be
fixed to correctly handle caches then?
If we give delay of 1 ms after handshake() the cache alignment warning
does not spew...but delay of 1 ms is not acceptable.
So I enabled the code to fetch first string desc length and then fetch
string desc fetch, in this way the issue is resolved.
It makes sense also to fetch string desc length and then actual string
desc....
I see, I understand now just about everything but the ehci problem, see
above. Your explanation was very helpful.
Let's work this out together!
Cheers!
M
Is this issue fixed or is this patch still needed? Thanks in advance!
This issue is not fixed and still need a patch to fix root cause,
explained above.
Note that this issue is observed even though we pass aligned address and
expects something from the device.
Best regards,
Marek Vasut
Thanx & Regards,
Puneet
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