From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751637AbbJaSoG (ORCPT ); Sat, 31 Oct 2015 14:44:06 -0400 Received: from unicorn.mansr.com ([81.2.72.234]:36866 "EHLO unicorn.mansr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750704AbbJaSoE convert rfc822-to-8bit (ORCPT ); Sat, 31 Oct 2015 14:44:04 -0400 From: =?iso-8859-1?Q?M=E5ns_Rullg=E5rd?= To: Francois Romieu Cc: linux-kernel@vger.kernel.org, netdev@vger.kernel.org Subject: Re: [PATCH v4] net: ethernet: add driver for Aurora VLSI NB8800 Ethernet controller References: <1446137333-1822-1-git-send-email-mans@mansr.com> <20151030222841.GA24712@electric-eye.fr.zoreil.com> <20151031180751.GA490@electric-eye.fr.zoreil.com> Date: Sat, 31 Oct 2015 18:44:02 +0000 In-Reply-To: <20151031180751.GA490@electric-eye.fr.zoreil.com> (Francois Romieu's message of "Sat, 31 Oct 2015 19:07:51 +0100") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.5 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Francois Romieu writes: > Måns Rullgård : >> Francois Romieu writes: > [...] >> > It looks like it receives, then tries to allocate new resources. If so >> > it may deplete the ring and you should instead consider allocating new >> > resources first, then receive data if alloc + map suceeded. >> >> The hardware receives a frame and stores it in the provided DMA buffer, >> then raises an interrupt and moves on to the next buffer. When a buffer >> is handed over to the network stack, a new one has to take its place in >> the DMA queue. I'm not sure how you're suggesting this be done >> differently. > > - The hardware raises an interrupt and moves on to the next packet > - The driver allocates a new buffer - call it Bob - and maps it. > - If it succeeds > - The driver unmaps the received packet > - The driver hands the received packet to the network stack > - The driver hands Bob to the hardware > - It it fails > - The driver updates the dropped packet stats > - The driver recycles the received - yet non-unmapped - packet to the > hardware Oh, I see. That's better. -- Måns Rullgård mans@mansr.com