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If DCD supports queuing of stall requests then USB MSC delay work-around is not necessary

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This commit is contained in:
Gregory Nutt 2014-03-20 15:20:50 -06:00
parent c6127ad09d
commit b0c2b54ec9
1 changed files with 19 additions and 10 deletions
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29
drivers/usbdev/usbmsc_scsi.c
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@ -81,18 +81,27 @@
/* Configuration ************************************************************/
/* Race condition workaround found by David Hewson. This race condition
/* Race condition workaround found by David Hewson. This race condition:
*
* "seems to relate to stalling the endpoint when a short response is
* generated which causes a residue to exist when the CSW would be returned.
* I think there's two issues here. The first being if the transfer which
* had just been queued before the stall had not completed then it wouldn't
* then complete once the endpoint was stalled? The second is that the
* subsequent transfer for the CSW would be dropped on the floor (by the
* epsubmit() function) if the end point was still stalled as the control
* transfer to resume it hadn't occurred."
* generated which causes a residue to exist when the CSW would be returned.
* I think there's two issues here. The first being if the transfer which
* had just been queued before the stall had not completed then it wouldn't
* then complete once the endpoint was stalled? The second is that the
* subsequent transfer for the CSW would be dropped on the floor (by the
* epsubmit() function) if the end point was still stalled as the control
* transfer to resume it hadn't occurred."
*
* If queuing of stall requests is supported by DCD then this workaround is
* not required. In this case, (1) the stall is not sent until all write
* requests preceding the stall request are sent, (2) the stall is sent,
* and then after the stall is cleared, (3) all write requests queued after
* the stall are sent.
*/
#define CONFIG_USBMSC_RACEWAR 1
#ifndef CONFIG_ARCH_USBDEV_STALLQUEUE
# define USBMSC_STALL_RACEWAR 1
#endif
/****************************************************************************
* Private Types
@ -2343,7 +2352,7 @@ static int usbmsc_cmdfinishstate(FAR struct usbmsc_dev_s *priv)
{
usbtrace(TRACE_CLSERROR(USBMSC_TRACEERR_CMDFINISHRESIDUE), (uint16_t)priv->residue);
#ifdef CONFIG_USBMSC_RACEWAR
#ifdef USBMSC_STALL_RACEWAR
/* (See description of the workaround at the top of the file).
* First, wait for the transfer to complete, then stall the endpoint
*/