Hi All,

Please let me know if the changes in this patch are okay . If the changes looks 
fine , can we proceed with this patch. 
 
Thanks,
Anurag Kumar Vulisha

>-----Original Message-----
>From: v.anuragku...@gmail.com [mailto:v.anuragku...@gmail.com]
>Sent: Tuesday, March 27, 2018 4:35 PM
>To: Felipe Balbi <ba...@kernel.org>; Greg Kroah-Hartman
><gre...@linuxfoundation.org>
>Cc: linux-usb@vger.kernel.org; linux-ker...@vger.kernel.org; Ajay Yugalkishore
>Pandey <apan...@xilinx.com>; v.anuragku...@gmail.com; Anurag Kumar Vulisha
><anura...@xilinx.com>
>Subject: [PATCH v2 1/2] usb: dwc3: gadget: Correct handling of scattergather 
>lists
>
>From: Anurag Kumar Vulisha <anura...@xilinx.com>
>
>The code logic in dwc3_prepare_one_trb() incorrectly uses the address and 
>length
>fields present in req packet for mapping TRB's instead of using the address 
>and length
>fields of scattergather lists. This patch correct's the code to use 
>sg->address and sg-
>>length when scattergather lists are present.
>
>Signed-off-by: Anurag Kumar Vulisha <anura...@xilinx.com>
>---
> Changes in v2:
>      1. Split the single patch into 2 patches as suggested by Felipe Balbi
>      2. Renamed sg_to_start variable to start_sg
>---
> drivers/usb/dwc3/core.h   |  2 ++
> drivers/usb/dwc3/gadget.c | 25 ++++++++++++++++++++++---
> 2 files changed, 24 insertions(+), 3 deletions(-)
>
>diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h index
>860d2bc..1406c4f 100644
>--- a/drivers/usb/dwc3/core.h
>+++ b/drivers/usb/dwc3/core.h
>@@ -718,6 +718,7 @@ struct dwc3_hwparams {
>  * @list: a list_head used for request queueing
>  * @dep: struct dwc3_ep owning this request
>  * @sg: pointer to first incomplete sg
>+ * @start_sg: pointer to the sg which should be queued next
>  * @num_pending_sgs: counter to pending sgs
>  * @remaining: amount of data remaining
>  * @epnum: endpoint number to which this request refers @@ -734,6 +735,7 @@
>struct dwc3_request {
>       struct list_head        list;
>       struct dwc3_ep          *dep;
>       struct scatterlist      *sg;
>+      struct scatterlist      *start_sg;
>
>       unsigned                num_pending_sgs;
>       unsigned                remaining;
>diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c index
>2bda4eb..330a4de 100644
>--- a/drivers/usb/dwc3/gadget.c
>+++ b/drivers/usb/dwc3/gadget.c
>@@ -978,11 +978,19 @@ static void dwc3_prepare_one_trb(struct dwc3_ep *dep,
>               struct dwc3_request *req, unsigned chain, unsigned node)  {
>       struct dwc3_trb         *trb;
>-      unsigned                length = req->request.length;
>+      unsigned int            length;
>+      dma_addr_t              dma;
>       unsigned                stream_id = req->request.stream_id;
>       unsigned                short_not_ok = req->request.short_not_ok;
>       unsigned                no_interrupt = req->request.no_interrupt;
>-      dma_addr_t              dma = req->request.dma;
>+
>+      if (req->request.num_sgs > 0) {
>+              length = sg_dma_len(req->start_sg);
>+              dma = sg_dma_address(req->start_sg);
>+      } else {
>+              length = req->request.length;
>+              dma = req->request.dma;
>+      }
>
>       trb = &dep->trb_pool[dep->trb_enqueue];
>
>@@ -1048,7 +1056,7 @@ static u32 dwc3_calc_trbs_left(struct dwc3_ep *dep)
>static void dwc3_prepare_one_trb_sg(struct dwc3_ep *dep,
>               struct dwc3_request *req)
> {
>-      struct scatterlist *sg = req->sg;
>+      struct scatterlist *sg = req->start_sg;
>       struct scatterlist *s;
>       int             i;
>
>@@ -1081,6 +1089,16 @@ static void dwc3_prepare_one_trb_sg(struct dwc3_ep
>*dep,
>                       dwc3_prepare_one_trb(dep, req, chain, i);
>               }
>
>+              /*
>+               * There can be a situation where all sgs in sglist are not
>+               * queued because of insufficient trb number. To handle this
>+               * case, update start_sg to next sg to be queued, so that
>+               * we have free trbs we can continue queuing from where we
>+               * previously stopped
>+               */
>+              if (chain)
>+                      req->start_sg = sg_next(s);
>+
>               if (!dwc3_calc_trbs_left(dep))
>                       break;
>       }
>@@ -1171,6 +1189,7 @@ static void dwc3_prepare_trbs(struct dwc3_ep *dep)
>                       return;
>
>               req->sg                 = req->request.sg;
>+              req->start_sg           = req->sg;
>               req->num_pending_sgs    = req->request.num_mapped_sgs;
>
>               if (req->num_pending_sgs > 0)
>--
>2.1.1

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