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From:   Thinh Nguyen <Thinh.Nguyen@synopsys.com>
To:     Anurag Kumar Vulisha <anurag.kumar.vulisha@xilinx.com>,
        "balbi@kernel.org" <balbi@kernel.org>,
        "gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>
CC:     "linux-usb@vger.kernel.org" <linux-usb@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "Thinh.Nguyen@synopsys.com" <Thinh.Nguyen@synopsys.com>,
        "v.anuragkumar@gmail.com" <v.anuragkumar@gmail.com>
Subject: Re: [PATCH v3 1/8] usb: dwc3: Correct the logic for checking TRB
 full in __dwc3_prepare_one_trb()
Thread-Topic: [PATCH v3 1/8] usb: dwc3: Correct the logic for checking TRB
 full in __dwc3_prepare_one_trb()
Thread-Index: AQHURqy3eaJ+tpig0kSKsepPhxN7aQ==
Date:   Fri, 7 Sep 2018 23:28:57 +0000
Message-ID: <30102591E157244384E984126FC3CB4F544AD8B3@us01wembx1.internal.synopsys.com>
References: <1536326029-16327-1-git-send-email-anurag.kumar.vulisha@xilinx.com>
 <1536326029-16327-2-git-send-email-anurag.kumar.vulisha@xilinx.com>
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Hi Anurag,=0A=
=0A=
On 9/7/2018 6:14 AM, Anurag Kumar Vulisha wrote:=0A=
> Availability of TRB's are calculated using dwc3_calc_trbs_left(), which=
=0A=
> determines available TRB's based on the HWO bit set in a TRB.=0A=
>=0A=
> __dwc3_prepare_one_trb() is called with a TRB which needs to be prepared=
=0A=
> for transfer. This __dwc3_prepare_one_trb() calls dwc3_calc_trbs_left()=
=0A=
> to determine total available TRBs and set IOC bit if the total available=
=0A=
> TRBs are zero. Since the present working TRB(which is passed as an=0A=
> argument to __dwc3_prepare_one_trb() )  doesn't have HWO bit already set,=
=0A=
> there are chances where dwc3_calc_trbs_left() wrongly calculates this=0A=
> present working TRB as free(since the HWO bit is not yet set). This could=
=0A=
> be a problem. This patch correct this issue by setting HWO bit before=0A=
> calling dwc3_calc_trbs_left()=0A=
=0A=
Please revise your commit message to reflect your new change.=0A=
=0A=
>=0A=
> Signed-off-by: Anurag Kumar Vulisha <anurag.kumar.vulisha@xilinx.com>=0A=
> Reviewed-by: Thinh Nguyen <thinhn@synopsys.com>=0A=
> ---=0A=
>  Changes in v3:=0A=
> 	1. Corrected the logic for setting HWO bit as suggested by "Thinh Nguyen=
"=0A=
>=0A=
>  Changes in v2:=0A=
> 	1. Changed the commit message=0A=
> ---=0A=
>  drivers/usb/dwc3/gadget.c | 6 +++---=0A=
>  1 file changed, 3 insertions(+), 3 deletions(-)=0A=
>=0A=
> diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c=0A=
> index 032ea7d..8a1622b 100644=0A=
> --- a/drivers/usb/dwc3/gadget.c=0A=
> +++ b/drivers/usb/dwc3/gadget.c=0A=
> @@ -911,8 +911,6 @@ static void __dwc3_prepare_one_trb(struct dwc3_ep *de=
p, struct dwc3_trb *trb,=0A=
>  	struct usb_gadget	*gadget =3D &dwc->gadget;=0A=
>  	enum usb_device_speed	speed =3D gadget->speed;=0A=
>  =0A=
> -	dwc3_ep_inc_enq(dep);=0A=
> -=0A=
>  	trb->size =3D DWC3_TRB_SIZE_LENGTH(length);=0A=
>  	trb->bpl =3D lower_32_bits(dma);=0A=
>  	trb->bph =3D upper_32_bits(dma);=0A=
> @@ -991,7 +989,7 @@ static void __dwc3_prepare_one_trb(struct dwc3_ep *de=
p, struct dwc3_trb *trb,=0A=
>  	}=0A=
>  =0A=
>  	if ((!no_interrupt && !chain) ||=0A=
> -			(dwc3_calc_trbs_left(dep) =3D=3D 0))=0A=
> +			(dwc3_calc_trbs_left(dep) =3D=3D 1))=0A=
>  		trb->ctrl |=3D DWC3_TRB_CTRL_IOC;=0A=
>  =0A=
>  	if (chain)=0A=
> @@ -1002,6 +1000,8 @@ static void __dwc3_prepare_one_trb(struct dwc3_ep *=
dep, struct dwc3_trb *trb,=0A=
>  =0A=
>  	trb->ctrl |=3D DWC3_TRB_CTRL_HWO;=0A=
>  =0A=
> +	dwc3_ep_inc_enq(dep);=0A=
> +=0A=
>  	trace_dwc3_prepare_trb(dep, trb);=0A=
>  }=0A=
>  =0A=
=0A=
BR,=0A=
Thinh=0A=