From mboxrd@z Thu Jan 1 00:00:00 1970 From: Timur Tabi Subject: Re: [PATCH 2/2] net: qcom/emac: add software control for pause frame mode Date: Tue, 1 Aug 2017 17:00:20 -0500 Message-ID: <9e7c0589-d163-a735-bb4c-87bc216164d2@codeaurora.org> References: <1501623460-3575-1-git-send-email-timur@codeaurora.org> <1501623460-3575-3-git-send-email-timur@codeaurora.org> <293ae5e0-c161-0c00-e40c-2583734aa2d4@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit To: Florian Fainelli , "David S. Miller" , netdev@vger.kernel.org Return-path: Received: from smtp.codeaurora.org ([198.145.29.96]:48716 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751938AbdHAWAW (ORCPT ); Tue, 1 Aug 2017 18:00:22 -0400 In-Reply-To: <293ae5e0-c161-0c00-e40c-2583734aa2d4@gmail.com> Content-Language: en-US Sender: netdev-owner@vger.kernel.org List-ID: On 08/01/2017 04:51 PM, Florian Fainelli wrote: > A few adapters (bcmgenet, bcmsysport) support configuring the pause > quanta so it would not be inconceivable to try to update > ethtool_pauseparam to include additional fields such as: Wouldn't this require a change to the user space tool? > - number of pause frames to send where we define an arbitrary high > default value (e.g: 0xffff), N < 0xffff is something drivers can test > for whether they support it, and 0 is only valid if pause is already > disabled > > - pause quanta (16-bits) > > Private flags are not usually that great and there could be more > adapters capable of doing the same pause frame number configuration, but > since there is no available knob it's hard to know. Well, for the EMAC, the quanta in this case would be either 1 or infinite. For other devices, it could be any combination of values. In a future revision of the hardware, we might support a variable quanta. And I suspect that some devices measure the quanta in time, not count. How would the user know what the acceptable values are? If I set the quanta to 10 via user space, and my driver truncates that to 1, I don't think that would be acceptable. -- Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm Technologies, Inc. Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.