From mboxrd@z Thu Jan 1 00:00:00 1970 From: laurent.pinchart@ideasonboard.com (Laurent Pinchart) Date: Sat, 16 Jan 2016 01:26:37 +0200 Subject: [PATCH v2 3/3] iommu/io-pgtable: Avoid redundant TLB syncs In-Reply-To: <20160112182754.GC22186@arm.com> References: <20160112182754.GC22186@arm.com> Message-ID: <1525049.idULaytocz@avalon> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Hi Robin, Thank you for the patch. On Tuesday 12 January 2016 18:27:55 Will Deacon wrote: > On Thu, Dec 17, 2015 at 08:50:59PM +0000, Robin Murphy wrote: > > In certain unmapping situations it is quite possible to end up issuing > > back-to-back TLB synchronisations, which at best is a waste of time and > > effort, and at worst causes some hardware to get rather confused. Whilst > > the pagetable implementations, or the IOMMU drivers, or both, could keep > > track of things to avoid this happening, it seems to make the most sense > > to prevent code duplication and add some simple state tracking in the > > common interface between the two. > > > > Signed-off-by: Robin Murphy > > --- > > > > drivers/iommu/io-pgtable.h | 9 ++++++++- > > 1 file changed, 8 insertions(+), 1 deletion(-) > > > > diff --git a/drivers/iommu/io-pgtable.h b/drivers/iommu/io-pgtable.h > > index 95c5565..d06219b 100644 > > --- a/drivers/iommu/io-pgtable.h > > +++ b/drivers/iommu/io-pgtable.h > > @@ -132,12 +132,14 @@ void free_io_pgtable_ops(struct io_pgtable_ops > > *ops); > > > > * @fmt: The page table format. > > * @cookie: An opaque token provided by the IOMMU driver and passed back > > to > > * any callback routines. > > > > + * @sync_flag: Private flag for optimising out redundant syncs. > > It makes sense to factor this out like you're proposing, but maybe we > can think of a better name? How about "tlb_sync_pending", to follow > "tlb_flush_pending" in the core code? With tlb_sync_pending, Reviewed-by: Laurent Pinchart -- Regards, Laurent Pinchart