From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756596AbdJMIPx (ORCPT ); Fri, 13 Oct 2017 04:15:53 -0400 Received: from mailout1.w1.samsung.com ([210.118.77.11]:48051 "EHLO mailout1.w1.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751307AbdJMIPt (ORCPT ); Fri, 13 Oct 2017 04:15:49 -0400 X-AuditID: cbfec7f1-f793a6d00000326b-6d-59e07631f420 Subject: Re: [PATCH] xhci: Set DMA parameters appropriately To: Robin Murphy , mathias.nyman@intel.com, gregkh@linuxfoundation.org Cc: linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, hch@lst.de, iommu@lists.linux-foundation.org From: Marek Szyprowski Message-id: <1cde45f2-cdd5-6210-dc00-49637132b897@samsung.com> Date: Fri, 13 Oct 2017 10:15:42 +0200 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.4.0 MIME-version: 1.0 In-reply-to: <347776be09eb0ca947c1c8ced46ee3ca92d92e28.1507730115.git.robin.murphy@arm.com> Content-type: text/plain; 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> } > > + dev->dma_parms = &xhci->dma_parms; > + dma_set_max_seg_size(dev, SZ_64K); > + dma_set_seg_boundary(dev, SZ_64K - 1); > + > xhci_dbg(xhci, "Calling HCD init\n"); > /* Initialize HCD and host controller data structures. */ > retval = xhci_init(hcd); > diff --git a/drivers/usb/host/xhci.h b/drivers/usb/host/xhci.h > index 7ef69ea0b480..afcae4cc908d 100644 > --- a/drivers/usb/host/xhci.h > +++ b/drivers/usb/host/xhci.h > @@ -1767,6 +1767,9 @@ struct xhci_hcd { > struct dma_pool *small_streams_pool; > struct dma_pool *medium_streams_pool; > > + /* DMA alignment restrictions */ > + struct device_dma_parameters dma_parms; > + > /* Host controller watchdog timer structures */ > unsigned int xhc_state; > Are you sure that xhci_hcd life time is proper to keep dma_parms? It looks that when driver gets removed and xhci_hcd is freed, the dma_parms will point to freed memory. Maybe it would make sense to clear dev->dma_parms somewhere or definitely change the way dma_parms are allocated? On the other hand 64K is the default segment size if no dma_parms are provided, so there is very little value added by this patch. Best regards -- Marek Szyprowski, PhD Samsung R&D Institute Poland