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[109.252.90.13]) by smtp.gmail.com with ESMTPSA id g28-v6sm8487459edg.67.2018.08.09.04.39.04 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 09 Aug 2018 04:39:05 -0700 (PDT) From: Dmitry Osipenko To: Thierry Reding Cc: Joerg Roedel , Robin Murphy , Jonathan Hunter , iommu@lists.linux-foundation.org, linux-tegra@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 2/8] iommu/tegra: gart: Provide access to Memory Controller driver Date: Thu, 09 Aug 2018 14:39:03 +0300 Message-ID: <16855111.9YhuyP46zb@dimapc> In-Reply-To: <20180809111746.GG21639@ulmo> References: <20180804143003.15817-1-digetx@gmail.com> <20180804143003.15817-3-digetx@gmail.com> <20180809111746.GG21639@ulmo> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thursday, 9 August 2018 14:17:46 MSK Thierry Reding wrote: > On Sat, Aug 04, 2018 at 05:29:57PM +0300, Dmitry Osipenko wrote: > > GART contain registers needed by the Memory Controller driver, provide > > access to the MC driver by utilizing its GART-integration facility. > > > > Signed-off-by: Dmitry Osipenko > > --- > > > > drivers/iommu/tegra-gart.c | 23 +++++++++++++++++++++++ > > 1 file changed, 23 insertions(+) > > > > diff --git a/drivers/iommu/tegra-gart.c b/drivers/iommu/tegra-gart.c > > index a004f6da35f2..f8b653e25914 100644 > > --- a/drivers/iommu/tegra-gart.c > > +++ b/drivers/iommu/tegra-gart.c > > @@ -31,6 +31,8 @@ > > > > #include > > #include > > > > +#include > > + > > > > #include > > > > /* bitmap of the page sizes currently supported */ > > > > @@ -41,6 +43,8 @@ > > > > #define GART_ENTRY_ADDR (0x28 - GART_REG_BASE) > > #define GART_ENTRY_DATA (0x2c - GART_REG_BASE) > > #define GART_ENTRY_PHYS_ADDR_VALID (1 << 31) > > > > +#define GART_ERROR_REQ (0x30 - GART_REG_BASE) > > +#define GART_ERROR_ADDR (0x34 - GART_REG_BASE) > > > > #define GART_PAGE_SHIFT 12 > > #define GART_PAGE_SIZE (1 << GART_PAGE_SHIFT) > > > > @@ -63,6 +67,8 @@ struct gart_device { > > > > struct device *dev; > > > > struct iommu_device iommu; /* IOMMU Core handle */ > > > > + > > + struct tegra_mc_gart_handle mc_gart_handle; > > > > }; > > > > struct gart_domain { > > > > @@ -408,6 +414,20 @@ static int tegra_gart_resume(struct device *dev) > > > > return 0; > > > > } > > > > +static u32 tegra_gart_error_addr(struct tegra_mc_gart_handle *handle) > > +{ > > + struct gart_device *gart = container_of(handle, struct gart_device, > > + mc_gart_handle); > > + return readl_relaxed(gart->regs + GART_ERROR_ADDR); > > +} > > + > > +static u32 tegra_gart_error_req(struct tegra_mc_gart_handle *handle) > > +{ > > + struct gart_device *gart = container_of(handle, struct gart_device, > > + mc_gart_handle); > > + return readl_relaxed(gart->regs + GART_ERROR_REQ); > > +} > > + > > > > static int tegra_gart_probe(struct platform_device *pdev) > > { > > > > struct gart_device *gart; > > > > @@ -464,6 +484,8 @@ static int tegra_gart_probe(struct platform_device > > *pdev)> > > gart->regs = gart_regs; > > gart->iovmm_base = (dma_addr_t)res_remap->start; > > gart->page_count = (resource_size(res_remap) >> GART_PAGE_SHIFT); > > > > + gart->mc_gart_handle.error_addr = tegra_gart_error_addr; > > + gart->mc_gart_handle.error_req = tegra_gart_error_req; > > > > gart->savedata = vmalloc(array_size(sizeof(u32), gart->page_count)); > > if (!gart->savedata) { > > > > @@ -475,6 +497,7 @@ static int tegra_gart_probe(struct platform_device > > *pdev)> > > do_gart_setup(gart, NULL); > > > > gart_handle = gart; > > > > + tegra_mc_register_gart(&gart->mc_gart_handle); > > > > return 0; > > > > } > > I see now why you've did it this way. We have separate devices unlike > with SMMU where it is properly modeled as part of the memory controller. > I think we should consider breaking ABI at this point and properly merge > both the memory controller and GART nodes. There's really no reason why > they should be separate and we're jumping through multiple hoops to do > what we need to do just because a few years back we made a mistake. > > I know we're technically not supposed to break the DT ABI, but I think > in this particular case we can make a good case for it. The current DT > bindings are plainly broken, and obviously so. Also, we don't currently > use the GART upstream for anything, so we can't break any existing > systems either. IIUC, that will require to break the stable DT ABI of the tegra20-mc, which is working fine and does its job. I'm personally not seeing the slight lameness of the current DT as a good excuse to break the ABI. Let's then break DT ABI on all Tegra's and convert them all to genpd and other goodies like assigned clock parents and clock rate.