Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750780AbdLZFAl (ORCPT ); Tue, 26 Dec 2017 00:00:41 -0500 Received: from smtp.codeaurora.org ([198.145.29.96]:53362 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750705AbdLZFAj (ORCPT ); Tue, 26 Dec 2017 00:00:39 -0500 DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org B9AC76055D Authentication-Results: pdx-caf-mail.web.codeaurora.org; dmarc=none (p=none dis=none) header.from=codeaurora.org Authentication-Results: pdx-caf-mail.web.codeaurora.org; spf=none smtp.mailfrom=mgautam@codeaurora.org Subject: Re: [PATCH] usb: gadget: uvc:change the UVC_NUM_REQUESTS value To: Lipengcheng , "balbi@kernel.org" Cc: "gregkh@linuxfoundation.org" , "linux-kernel@vger.kernel.org" , "linux-usb@vger.kernel.org" References: <637796ED17F7774FB27D6AAE3C6951584B38D3F6@dggeml508-mbx.china.huawei.com> From: Manu Gautam Message-ID: <2afb9306-b957-9f60-f103-e1d5912e0218@codeaurora.org> Date: Tue, 26 Dec 2017 10:30:33 +0530 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.5.0 MIME-Version: 1.0 In-Reply-To: <637796ED17F7774FB27D6AAE3C6951584B38D3F6@dggeml508-mbx.china.huawei.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1473 Lines: 40 Hi, On 12/26/2017 8:22 AM, Lipengcheng wrote: > The value is 4, it can cache four descriptors. When streaming_interval = 1, > it can tolerate 500us. Some busy scenes, it may be more than 500us because > cpu scheduling is not timely. There will have some problems. It is better > set to eight. > > Signed-off-by: Pengcheng Li > --- > drivers/usb/gadget/function/uvc.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/usb/gadget/function/uvc.h b/drivers/usb/gadget/function/uvc.h > index a64e07e..901487e 100644 > --- a/drivers/usb/gadget/function/uvc.h > +++ b/drivers/usb/gadget/function/uvc.h > @@ -90,7 +90,7 @@ extern unsigned int uvc_gadget_trace_param; > * Driver specific constants > */ > > -#define UVC_NUM_REQUESTS 4 > +#define UVC_NUM_REQUESTS 8 Can we rather make it 16? I ran into similar issue on QCOM platform with DWC3 and with 8 requests also data loss was observed. 16 requests (i.e. ~2msec) worked fine. > #define UVC_MAX_REQUEST_SIZE 64 > #define UVC_MAX_EVENTS 4 > > -- > 2.7.4 > > N�����r��y���b�X��ǧv�^�)޺{.n�+����{�����^n�r���z���h����&���G���h�(�階�ݢj"���m�����z�ޖ���f���h���~�mml== -- The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project