Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756494AbcK2KUC (ORCPT ); Tue, 29 Nov 2016 05:20:02 -0500 Received: from mail.free-electrons.com ([62.4.15.54]:48711 "EHLO mail.free-electrons.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750853AbcK2KTx (ORCPT ); Tue, 29 Nov 2016 05:19:53 -0500 From: Gregory CLEMENT To: Marcin Wojtas Cc: "David S. Miller" , linux-kernel@vger.kernel.org, netdev@vger.kernel.org, Jisheng Zhang , Arnd Bergmann , Jason Cooper , Andrew Lunn , Sebastian Hesselbarth , Thomas Petazzoni , "linux-arm-kernel\@lists.infradead.org" , Nadav Haklai , Dmitri Epshtein , Yelena Krivosheev Subject: Re: [PATCH v3 net-next 2/6] net: mvneta: Use cacheable memory to store the rx buffer virtual address References: Date: Tue, 29 Nov 2016 11:19:52 +0100 In-Reply-To: (Marcin Wojtas's message of "Tue, 29 Nov 2016 10:59:25 +0100") Message-ID: <87shqafv07.fsf@free-electrons.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.5 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3960 Lines: 109 Hi Marcin, On mar., nov. 29 2016, Marcin Wojtas wrote: > Hi Gregory, > > Another remark below, sorry for noise. > > 2016-11-29 10:37 GMT+01:00 Gregory CLEMENT : >> Until now the virtual address of the received buffer were stored in the >> cookie field of the rx descriptor. However, this field is 32-bits only >> which prevents to use the driver on a 64-bits architecture. >> >> With this patch the virtual address is stored in an array not shared with >> the hardware (no more need to use the DMA API). Thanks to this, it is >> possible to use cache contrary to the access of the rx descriptor member. >> >> The change is done in the swbm path only because the hwbm uses the cookie >> field, this also means that currently the hwbm is not usable in 64-bits. >> >> Signed-off-by: Gregory CLEMENT >> --- >> drivers/net/ethernet/marvell/mvneta.c | 93 ++++++++++++++++++++++++---- >> 1 file changed, 81 insertions(+), 12 deletions(-) >> >> diff --git a/drivers/net/ethernet/marvell/mvneta.c b/drivers/net/ethernet/marvell/mvneta.c >> index 1b84f746d748..32b142d0e44e 100644 >> --- a/drivers/net/ethernet/marvell/mvneta.c >> +++ b/drivers/net/ethernet/marvell/mvneta.c >> @@ -561,6 +561,9 @@ struct mvneta_rx_queue { >> u32 pkts_coal; >> u32 time_coal; >> >> + /* Virtual address of the RX buffer */ >> + void **buf_virt_addr; >> + >> /* Virtual address of the RX DMA descriptors array */ >> struct mvneta_rx_desc *descs; >> >> @@ -1573,10 +1576,14 @@ static void mvneta_tx_done_pkts_coal_set(struct mvneta_port *pp, >> >> /* Handle rx descriptor fill by setting buf_cookie and buf_phys_addr */ >> static void mvneta_rx_desc_fill(struct mvneta_rx_desc *rx_desc, >> - u32 phys_addr, u32 cookie) >> + u32 phys_addr, void *virt_addr, >> + struct mvneta_rx_queue *rxq) >> { >> - rx_desc->buf_cookie = cookie; >> + int i; >> + >> rx_desc->buf_phys_addr = phys_addr; >> + i = rx_desc - rxq->descs; >> + rxq->buf_virt_addr[i] = virt_addr; >> } >> >> /* Decrement sent descriptors counter */ >> @@ -1781,7 +1788,8 @@ EXPORT_SYMBOL_GPL(mvneta_frag_free); >> >> /* Refill processing for SW buffer management */ >> static int mvneta_rx_refill(struct mvneta_port *pp, >> - struct mvneta_rx_desc *rx_desc) >> + struct mvneta_rx_desc *rx_desc, >> + struct mvneta_rx_queue *rxq) >> >> { >> dma_addr_t phys_addr; >> @@ -1799,7 +1807,7 @@ static int mvneta_rx_refill(struct mvneta_port *pp, >> return -ENOMEM; >> } >> >> - mvneta_rx_desc_fill(rx_desc, phys_addr, (u32)data); >> + mvneta_rx_desc_fill(rx_desc, phys_addr, data, rxq); >> return 0; >> } >> >> @@ -1861,7 +1869,12 @@ static void mvneta_rxq_drop_pkts(struct mvneta_port *pp, >> >> for (i = 0; i < rxq->size; i++) { >> struct mvneta_rx_desc *rx_desc = rxq->descs + i; >> - void *data = (void *)rx_desc->buf_cookie; >> + void *data; >> + >> + if (!pp->bm_priv) >> + data = rxq->buf_virt_addr[i]; >> + else >> + data = (void *)(uintptr_t)rx_desc->buf_cookie; > > Dropping packets for HWBM (in fact returning dropped buffers to the > pool) is done a couple of lines above. This point will never be indeed I changed the code at every place the buf_cookie was used and missed the fact that for HWBM this code was never reached. > reached with HWBM enabled (and it's also incorrect). What is incorrect? Gregory > > Best regards, > Marcin -- Gregory Clement, Free Electrons Kernel, drivers, real-time and embedded Linux development, consulting, training and support. http://free-electrons.com