| From: Erkka Talvitie <erkka.talvitie@vincit.fi> |
| Date: Wed, 11 Dec 2019 10:08:39 +0200 |
| Subject: USB: EHCI: Do not return -EPIPE when hub is disconnected |
| |
| 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.1576050523.git.erkka.talvitie@vincit.fi |
| 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; |