3.16.83-rc1 review patch. If anyone has any objections, please let me know.
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From: Erkka Talvitie erkka.talvitie@vincit.fi
commit 64cc3f12d1c7dd054a215bc1ff9cc2abcfe35832 upstream.
When disconnecting a USB hub that has some child device(s) connected to it (such as a USB mouse), then the stack tries to clear halt and reset device(s) which are _already_ physically disconnected.
The issue has been reproduced with:
CPU: IMX6D5EYM10AD or MCIMX6D5EYM10AE. SW: U-Boot 2019.07 and kernel 4.19.40.
CPU: HP Proliant Microserver Gen8. SW: Linux version 4.2.3-300.fc23.x86_64
In this situation there will be error bit for MMF active yet the CERR equals EHCI_TUNE_CERR + halt. Existing implementation interprets this as a stall [1] (chapter 8.4.5).
The possible conditions when the MMF will be active + halt can be found from [2] (Table 4-13).
Fix for the issue is to check whether MMF is active and PID Code is IN before checking for the stall. If these conditions are true then it is not a stall.
What happens after the fix is that when disconnecting a hub with attached device(s) the situation is not interpret as a stall.
[1] [https://www.usb.org/document-library/usb-20-specification, usb_20.pdf] [2] [https://www.intel.com/content/dam/www/public/us/en/documents/ technical-specifications/ehci-specification-for-usb.pdf]
Signed-off-by: Erkka Talvitie erkka.talvitie@vincit.fi Reviewed-by: Alan Stern stern@rowland.harvard.edu Link: https://lore.kernel.org/r/ef70941d5f349767f19c0ed26b0dd9eed8ad81bb.157605052... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Ben Hutchings ben@decadent.org.uk --- drivers/usb/host/ehci-q.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-)
--- a/drivers/usb/host/ehci-q.c +++ b/drivers/usb/host/ehci-q.c @@ -40,6 +40,10 @@
/*-------------------------------------------------------------------------*/
+/* PID Codes that are used here, from EHCI specification, Table 3-16. */ +#define PID_CODE_IN 1 +#define PID_CODE_SETUP 2 + /* fill a qtd, returning how much of the buffer we were able to queue up */
static int @@ -199,7 +203,7 @@ static int qtd_copy_status ( int status = -EINPROGRESS;
/* count IN/OUT bytes, not SETUP (even short packets) */ - if (likely (QTD_PID (token) != 2)) + if (likely(QTD_PID(token) != PID_CODE_SETUP)) urb->actual_length += length - QTD_LENGTH (token);
/* don't modify error codes */ @@ -215,6 +219,13 @@ static int qtd_copy_status ( if (token & QTD_STS_BABBLE) { /* FIXME "must" disable babbling device's port too */ status = -EOVERFLOW; + /* + * When MMF is active and PID Code is IN, queue is halted. + * EHCI Specification, Table 4-13. + */ + } else if ((token & QTD_STS_MMF) && + (QTD_PID(token) == PID_CODE_IN)) { + status = -EPROTO; /* CERR nonzero + halt --> stall */ } else if (QTD_CERR(token)) { status = -EPIPE;