Signed-off-by: Luben Tuikov <ltuikov@xxxxxxxxx>
---
The long story is that we see some host controllers misreport their
PSA as they solved 2^v = streams, instead of 2^(v+1) = streams. Thus
They report that they support 32 streams when in fact they support 16.
When the device attempts to return status for stream > 15, the host
says ACK(NumP=0), the device goes in flow control, blah, blah, this
module parameter allows you to set a max cap on the number of streams
the driver will ask XHCI HCD to allocate.
drivers/usb/storage/uasp.c | 21 ++++++++++++++++++++-
1 files changed, 20 insertions(+), 1 deletions(-)
diff --git a/drivers/usb/storage/uasp.c b/drivers/usb/storage/uasp.c
index 3b10efd..e5a26e9 100644
--- a/drivers/usb/storage/uasp.c
+++ b/drivers/usb/storage/uasp.c
@@ -30,6 +30,19 @@
#include <scsi/scsi_host.h>
#include <scsi/scsi_tcq.h>
+int MaxNumStreams = -1;
+
+module_param(MaxNumStreams, int, 0444);
+MODULE_PARM_DESC(MaxNumStreams, "\n"
+ "\tSome host controllers and/or devices report a larger number of\n"
+ "\tstreams that they in fact support. This parameter allows you\n"
+ "\tto limit the number of streams this driver will request the XHCI\n"
+ "\tHCD to allocate. If set to -1, the default value, then this driver\n"
+ "\twill use the value reported by the attached device. Else the\n"
+ "\tnumber of streams will be limited to the minimum reported by the\n"
+ "\tattached device and this value. Valid values are -1, default,\n"
+ "\tand 1 to 0xFFEF.");
+
/* Information unit types
*/
#define IU_CMD 1
@@ -938,6 +951,8 @@ static int uasp_ep_conf(struct uasp_tport_info *tpinfo)
tpinfo->eps[3]->desc.bEndpointAddress);
if (udev->speed == USB_SPEED_SUPER) {
+ int max_streams;
+
for (i = 1; i < 4; i++) {
if (tpinfo->max_streams == 0)
tpinfo->max_streams = USB_SS_MAX_STREAMS(tpinfo->eps[i]->ss_ep_comp.bmAttributes);
@@ -952,9 +967,13 @@ static int uasp_ep_conf(struct uasp_tport_info *tpinfo)
}
tpinfo->use_streams = 1;
+ if (1 <= MaxNumStreams && MaxNumStreams <= 0xFFEF)
+ max_streams = min(MaxNumStreams, tpinfo->max_streams);
+ else
+ max_streams = tpinfo->max_streams;
tpinfo->num_streams = usb_alloc_streams(iface,
&tpinfo->eps[1], 3,
- tpinfo->max_streams,
+ max_streams,
GFP_KERNEL);
if (tpinfo->num_streams <= 0) {
dev_err(&udev->dev,
--
1.7.0.1
--
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