From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sergei Shtylyov Subject: Re: [PATCH] ravb: do not invalidate cache for RX buffer twice Date: Wed, 15 Jul 2015 13:45:34 +0300 Message-ID: <55A639CE.2030201@cogentembedded.com> References: <4759713.2ulGRKsd9L@wasted.cogentembedded.com> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Cc: linux-sh@vger.kernel.org To: netdev@vger.kernel.org Return-path: In-Reply-To: <4759713.2ulGRKsd9L@wasted.cogentembedded.com> Sender: linux-sh-owner@vger.kernel.org List-Id: netdev.vger.kernel.org Hello. On 7/15/2015 12:56 AM, Sergei Shtylyov wrote: > First, dma_sync_single_for_cpu() shouldn't have been called in the first place > (it's a streaming DMA API). dma_unmap_single() should have been called instead. ^ Oops, I meant comma here. > Second, dma_unmap_single() call after handing the buffer to napi_gro_receive() > makes little sense. Moreover, 'desc->dptr' may not be valid at this point... > Signed-off-by: Sergei Shtylyov > > --- > The patch is against Dave Miller's 'net.git' repo. > Don't know why I missed this DMA API misuse while working on the driver. :-< Dave, do you want me to resend the patch with fixed up changelog? > drivers/net/ethernet/renesas/ravb_main.c | 10 +++------- > 1 file changed, 3 insertions(+), 7 deletions(-) > > Index: net/drivers/net/ethernet/renesas/ravb_main.c > =================================================================== > --- net.orig/drivers/net/ethernet/renesas/ravb_main.c > +++ net/drivers/net/ethernet/renesas/ravb_main.c [...] > @@ -584,9 +583,6 @@ static bool ravb_rx(struct net_device *n > if (!skb) > break; /* Better luck next round. */ > ravb_set_buffer_align(skb); > - dma_unmap_single(&ndev->dev, le32_to_cpu(desc->dptr), > - ALIGN(PKT_BUF_SZ, 16), > - DMA_FROM_DEVICE); > dma_addr = dma_map_single(&ndev->dev, skb->data, > le16_to_cpu(desc->ds_cc), > DMA_FROM_DEVICE); WBR, Sergei