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usb: properly detect empty mass storage media reader 

When a USB card reader is empty, it will return "Not Ready - medium not
present" as Key Code Qualifier. In that situation, it's useless waiting
for the full timeout since the result won't change until the user
inserts a card.

Signed-off-by: Vincent Palatin <vpalatin@chromium.org>
Signed-off-by: Vadim Bendebury <vbendeb@chromium.org>
Signed-off-by: Simon Glass <sjg@chromium.org>
This commit is contained in:
Vincent Palatin 2012-12-12 17:55:29 -08:00 committed by Marek Vasut
parent 359439d288
commit 8b57e2f081
1 changed files with 10 additions and 0 deletions
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10
common/usb_storage.c
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@ -970,6 +970,16 @@ static int usb_test_unit_ready(ccb *srb, struct us_data *ss)
return 0;
}
usb_request_sense(srb, ss);
/*
* Check the Key Code Qualifier, if it matches
* "Not Ready - medium not present"
* (the sense Key equals 0x2 and the ASC is 0x3a)
* return immediately as the medium being absent won't change
* unless there is a user action.
*/
if ((srb->sense_buf[2] == 0x02) &&
(srb->sense_buf[12] == 0x3a))
return -1;
mdelay(100);
} while (retries--);