From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753740AbcFHARJ (ORCPT ); Tue, 7 Jun 2016 20:17:09 -0400 Received: from galahad.ideasonboard.com ([185.26.127.97]:42780 "EHLO galahad.ideasonboard.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750818AbcFHARH (ORCPT ); Tue, 7 Jun 2016 20:17:07 -0400 From: Laurent Pinchart To: Magnus Damm Cc: iommu@lists.linux-foundation.org, laurent.pinchart+renesas@ideasonboard.com, geert+renesas@glider.be, joro@8bytes.org, linux-kernel@vger.kernel.org, linux-renesas-soc@vger.kernel.org, horms+renesas@verge.net.au Subject: Re: [PATCH 2/3] iommu/ipmmu-vmsa: Increase maximum micro-TLBS to 48 Date: Wed, 08 Jun 2016 03:17:17 +0300 Message-ID: <1502675.8oO2rJ9tLe@avalon> User-Agent: KMail/4.14.10 (Linux/4.4.6-gentoo; KDE/4.14.16; x86_64; ; ) In-Reply-To: <20160607033936.28687.78365.sendpatchset@little-apple> References: <20160607033918.28687.98260.sendpatchset@little-apple> <20160607033936.28687.78365.sendpatchset@little-apple> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Magnus, Thank you for the patch. On Tuesday 07 Jun 2016 12:39:36 Magnus Damm wrote: > From: Magnus Damm > > Bump up the maximum numbers of micro-TLBS to 48. > > Each IPMMU device instance get micro-TLB assignment via > the "iommus" property in DT. Older SoCs tend to use a > maximum number of 32 micro-TLBd per IPMMU instance however > newer SoCs such as r8a7796 make use of up to 48 micro-TLBs. > > At this point no SoC specific handling is done to validate > the maximum number of micro-TLBs, and because of that the > DT information is assumed to be within correct range for > each particular SoC. > > If needed in the future SoC specific feature flags can be > added to handle the maximum number of micro-TLBs without > requiring DT changes, however at this point this does not > seem necessary. > > Signed-off-by: Magnus Damm > --- > > drivers/iommu/ipmmu-vmsa.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > --- 0029/drivers/iommu/ipmmu-vmsa.c > +++ work/drivers/iommu/ipmmu-vmsa.c 2016-06-06 11:17:33.230607110 +0900 > @@ -1115,7 +1115,7 @@ static int ipmmu_probe(struct platform_d > } > > mmu->dev = &pdev->dev; > - mmu->num_utlbs = 32; > + mmu->num_utlbs = 48; This value is only used to validate that all utlb numbers in the bus master DT nodes are within the range acceptable by the device. If we bump it up unconditionally we could as well remove it completely. A possibly better alternative would be to specify the number of utlbs, or even the mask of implemented utlbs, in the DT node of the IPMMU. Why 48 by the way ? The IPMMU instance with the largest utlb number in the R- Car Gen3 datasheet uses a 0-38 utlb range. > spin_lock_init(&mmu->lock); > bitmap_zero(mmu->ctx, IPMMU_CTX_MAX); > mmu->features = match->data; -- Regards, Laurent Pinchart