Re: [PATCH v10 09/23] iommu/io-pgtable-arm-v7s: Extend to support PA[33:32] for MediaTek

From: Yong Wu <yong.wu@mediatek.com>
To: Will Deacon <will@kernel.org>
Cc: <youlin.pei@mediatek.com>, <devicetree@vger.kernel.org>,
	Nicolas Boichat <drinkcat@chromium.org>, <cui.zhang@mediatek.com>,
	<srv_heupstream@mediatek.com>, <chao.hao@mediatek.com>,
	Joerg Roedel <joro@8bytes.org>, <linux-kernel@vger.kernel.org>,
	Evan Green <evgreen@chromium.org>, Tomasz Figa <tfiga@google.com>,
	<iommu@lists.linux-foundation.org>,
	Rob Herring <robh+dt@kernel.org>,
	<linux-mediatek@lists.infradead.org>,
	Matthias Brugger <matthias.bgg@gmail.com>,
	<ming-fan.chen@mediatek.com>, <anan.sun@mediatek.com>,
	Robin Murphy <robin.murphy@arm.com>,
	"Matthias Kaehlcke" <mka@chromium.org>,
	<linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH v10 09/23] iommu/io-pgtable-arm-v7s: Extend to support PA[33:32] for MediaTek
Date: Thu, 22 Aug 2019 16:56:26 +0800	[thread overview]
Message-ID: <1566464186.11621.7.camel@mhfsdcap03> (raw)
In-Reply-To: <20190821152448.qmoqjh5zznfpdi6n@willie-the-truck>

On Wed, 2019-08-21 at 16:24 +0100, Will Deacon wrote:
> On Wed, Aug 21, 2019 at 09:53:12PM +0800, Yong Wu wrote:
> > MediaTek extend the arm v7s descriptor to support up to 34 bits PA where
> > the bit32 and bit33 are encoded in the bit9 and bit4 of the PTE
> > respectively. Meanwhile the iova still is 32bits.
> > 
> > Regarding whether the pagetable address could be over 4GB, the mt8183
> > support it while the previous mt8173 don't, thus keep it as is.
> > 
> > Signed-off-by: Yong Wu <yong.wu@mediatek.com>
> > ---
> >  drivers/iommu/io-pgtable-arm-v7s.c | 32 +++++++++++++++++++++++++-------
> >  include/linux/io-pgtable.h         |  7 +++----
> >  2 files changed, 28 insertions(+), 11 deletions(-)
> 
> [...]
> 
> > @@ -731,7 +747,9 @@ static struct io_pgtable *arm_v7s_alloc_pgtable(struct io_pgtable_cfg *cfg,
> >  {
> >  	struct arm_v7s_io_pgtable *data;
> >  
> > -	if (cfg->ias > ARM_V7S_ADDR_BITS || cfg->oas > ARM_V7S_ADDR_BITS)
> > +	if (cfg->ias > ARM_V7S_ADDR_BITS ||
> > +	    (cfg->oas > ARM_V7S_ADDR_BITS &&
> > +	     !(cfg->quirks & IO_PGTABLE_QUIRK_ARM_MTK_EXT)))
> 
> Please can you instead change arm_v7s_alloc_pgtable() so that it allows an
> ias of up to 34 when the IO_PGTABLE_QUIRK_ARM_MTK_EXT is set?

Here I only simply skip the oas checking for our case. then which way do
your prefer?  something like you commented before:?

	if (cfg->ias > ARM_V7S_ADDR_BITS)
		return NULL;

	if (cfg->quirks & IO_PGTABLE_QUIRK_ARM_MTK_EXT) {
		if (!IS_ENABLED(CONFIG_PHYS_ADDR_T_64BIT))
			cfg->oas = min(cfg->oas, ARM_V7S_ADDR_BITS);
		else if (cfg->oas > 34)
			return NULL;
	} else if (cfg->oas > ARM_V7S_ADDR_BITS) {
		return NULL;
	}

> 
> With that change:
> 
> Acked-by: Will Deacon <will@kernel.org>
> 
> Will
> 
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