From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thomas Bogendoerfer Subject: Re: [PATCH 22/28] sgiseeq: convert from dma_cache_sync to dma_sync_single_for_device Date: Wed, 2 Sep 2020 23:38:09 +0200 Message-ID: <20200902213809.GA7998@alpha.franken.de> References: <20200819065555.1802761-1-hch@lst.de> <20200819065555.1802761-23-hch@lst.de> <20200901152209.GA14288@alpha.franken.de> <20200901171241.GA20685@alpha.franken.de> <20200901171627.GA8255@lst.de> <20200901173810.GA25282@alpha.franken.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20200901173810.GA25282@alpha.franken.de> Sender: linux-samsung-soc-owner@vger.kernel.org To: Christoph Hellwig Cc: alsa-devel@alsa-project.org, linux-ia64@vger.kernel.org, linux-doc@vger.kernel.org, nouveau@lists.freedesktop.org, linux-nvme@lists.infradead.org, linux-kernel@vger.kernel.org, "James E.J. Bottomley" , linux-mm@kvack.org, Marek Szyprowski , linux-samsung-soc@vger.kernel.org, Joonyoung Shim , linux-scsi@vger.kernel.org, Kyungmin Park , Ben Skeggs , Matt Porter , linux-media@vger.kernel.org, Tom Lendacky , Pawel Osciak , Mauro Carvalho Chehab , linux-arm-kernel@lists.infradead.org, linux-parisc@vger.kernel.org, netdev@vger.kernel.org List-Id: nouveau.vger.kernel.org On Tue, Sep 01, 2020 at 07:38:10PM +0200, Thomas Bogendoerfer wrote: > On Tue, Sep 01, 2020 at 07:16:27PM +0200, Christoph Hellwig wrote: > > Well, if IP22 doesn't speculate (which I'm pretty sure is the case), > > dma_sync_single_for_cpu should indeeed be a no-op. But then there > > also shouldn't be anything in the cache, as the previous > > dma_sync_single_for_device should have invalidated it. So it seems like > > we are missing one (or more) ownership transfers to the device. I'll > > try to look at the the ownership management in a little more detail > > tomorrow. > > this is the problem: > > /* Always check for received packets. */ > sgiseeq_rx(dev, sp, hregs, sregs); > > so the driver will look at the rx descriptor on every interrupt, so > we cache the rx descriptor on the first interrupt and if there was > $no rx packet, we will only see it, if cache line gets flushed for > some other reason. kick_tx() does a busy loop checking tx descriptors, > with just sync_desc_cpu... the patch below fixes the problem. Thomas. diff --git a/drivers/net/ethernet/seeq/sgiseeq.c b/drivers/net/ethernet/seeq/sgiseeq.c index 8507ff242014..876e3700a0e4 100644 --- a/drivers/net/ethernet/seeq/sgiseeq.c +++ b/drivers/net/ethernet/seeq/sgiseeq.c @@ -112,14 +112,18 @@ struct sgiseeq_private { static inline void dma_sync_desc_cpu(struct net_device *dev, void *addr) { - dma_cache_sync(dev->dev.parent, addr, sizeof(struct sgiseeq_rx_desc), - DMA_FROM_DEVICE); + struct sgiseeq_private *sp = netdev_priv(dev); + + dma_sync_single_for_device(dev->dev.parent, VIRT_TO_DMA(sp, addr), + sizeof(struct sgiseeq_rx_desc), DMA_FROM_DEVICE); } static inline void dma_sync_desc_dev(struct net_device *dev, void *addr) { - dma_cache_sync(dev->dev.parent, addr, sizeof(struct sgiseeq_rx_desc), - DMA_TO_DEVICE); + struct sgiseeq_private *sp = netdev_priv(dev); + + dma_sync_single_for_device(dev->dev.parent, VIRT_TO_DMA(sp, addr), + sizeof(struct sgiseeq_rx_desc), DMA_TO_DEVICE); } -- Crap can work. Given enough thrust pigs will fly, but it's not necessarily a good idea. [ RFC1925, 2.3 ]