From mboxrd@z Thu Jan 1 00:00:00 1970 From: Laurent Pinchart Subject: Re: [PATCH 2/5] iommu/ipmmu-vmsa: Add device tree bindings documentation Date: Mon, 31 Mar 2014 12:18:04 +0200 Message-ID: <2135036.3YMfppXtgo@avalon> References: <1396049781-12941-1-git-send-email-laurent.pinchart+renesas@ideasonboard.com> <1396049781-12941-3-git-send-email-laurent.pinchart+renesas@ideasonboard.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7Bit Return-path: In-Reply-To: Sender: linux-sh-owner@vger.kernel.org To: Geert Uytterhoeven Cc: Laurent Pinchart , iommu@lists.linux-foundation.org, Linux-sh list , "devicetree@vger.kernel.org" , Will Deacon List-Id: devicetree@vger.kernel.org Hi Geert, On Monday 31 March 2014 10:39:48 Geert Uytterhoeven wrote: > On Sat, Mar 29, 2014 at 12:36 AM, Laurent Pinchart wrote: > > +Required Properties: > > + > > + - compatible: Must contain "renesas,ipmmu-vmsa". > > + - reg: Base address and size of the IPMMU registers. > > + - interrupts: Specifier for the MMU fault interrupt. > > Does it make sense to have a property for the number of micro-TLBs, > or is this handled transparently? > > E.g. ipmmu_mx has 24 micro-TLBs, but ipmmu_mp has 30. The IPMMU driver doesn't need to know the number of micro-TLBs, so we should be fine without specifying it in DT. The micro-TLBs are configured when a bus master device is attached or detached, and at that point the device provides its micro-TLB number. The only reason I can foresee why the number of micro-TLBs would be useful is to iterate over micro-TLBs when the driver probes the device to disable them all. A mask would probably be better than a number in that case, and I think we can always add that later if we find a need for it. -- Regards, Laurent Pinchart