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mx.zohomail.com; dkim=pass header.i=collabora.com; spf=pass smtp.mailfrom=benjamin.gaignard@collabora.com; dmarc=pass header.from= DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; t=1768321546; s=zohomail; d=collabora.com; i=benjamin.gaignard@collabora.com; h=Message-ID:Date:Date:MIME-Version:Subject:Subject:To:To:Cc:Cc:References:From:From:In-Reply-To:Content-Type:Content-Transfer-Encoding:Message-Id:Reply-To; bh=8MTiHfloStfO84sC7uhvGAOAjhnPQBxw01aUbUwJ3uE=; b=bFsn/J3vxgypV86zjeTIuOFJba9OL7HTRMgwvfjDsAWBPlJqF5E9KD/xVc6mLg/A z699RwO9we9zu32cwiVCaTr0RyW756EanyoVO6BITFHOkh7cbSZHv6VO63qwc4PN1T8 v4A4I79/8OHgO7pEwg7pT5zNNzTrbj1vp17KxPV4= Received: by mx.zohomail.com with SMTPS id 1768321544021680.0980354267477; Tue, 13 Jan 2026 08:25:44 -0800 (PST) Message-ID: <68a49f8b-178c-4fa2-b4a9-315ad602271d@collabora.com> Date: Tue, 13 Jan 2026 17:25:38 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v11 3/7] iommu: Add verisilicon IOMMU driver To: Will Deacon Cc: joro@8bytes.org, robin.murphy@arm.com, robh@kernel.org, krzk+dt@kernel.org, conor+dt@kernel.org, heiko@sntech.de, nicolas.dufresne@collabora.com, p.zabel@pengutronix.de, mchehab@kernel.org, iommu@lists.linux.dev, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-rockchip@lists.infradead.org, linux-media@vger.kernel.org, kernel@collabora.com References: <20260107101005.84039-1-benjamin.gaignard@collabora.com> <20260107101005.84039-4-benjamin.gaignard@collabora.com> Content-Language: en-US From: Benjamin Gaignard In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260113_082600_536142_27D81A2B X-CRM114-Status: GOOD ( 28.22 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Le 13/01/2026 à 17:10, Will Deacon a écrit : > Hi Benjamin, > > Thanks for posting a v11. > > On Wed, Jan 07, 2026 at 11:09:53AM +0100, Benjamin Gaignard wrote: >> The Verisilicon IOMMU hardware block can be found in combination >> with Verisilicon hardware video codecs (encoders or decoders) on >> different SoCs. >> Enable it will allow us to use non contiguous memory allocators >> for Verisilicon video codecs. >> If both decoder and this iommu driver are compiled has modules >> there is undefined symboles issues so this iommu driver could >> only be compiled has built-in. >> >> Signed-off-by: Benjamin Gaignard >> --- >> changes in version 11: >> - Fix dependency issue when decoder driver is build as module. >> >> drivers/iommu/Kconfig | 11 + >> drivers/iommu/Makefile | 1 + >> drivers/iommu/vsi-iommu.c | 808 ++++++++++++++++++++++++++++++++++++++ >> include/linux/vsi-iommu.h | 21 + >> 4 files changed, 841 insertions(+) >> create mode 100644 drivers/iommu/vsi-iommu.c >> create mode 100644 include/linux/vsi-iommu.h > Based on your reply to v9: > > https://lore.kernel.org/all/0eff8b1a-c45f-47b1-a871-59f4a0101f0f@collabora.com/ > > I took another look at this to see whether it had changed significantly > from v6 when compared to the rockchip driver. Sadly, they still look > very similar to me and I continue to suspect that the hardware is a > derivative. I really don't understand why having a shared implementation > of the default domain ops is difficult or controversial. Have you tried > to write it? > > However, given that nobody from the Rockchip side has contributed to the > discussion and you claim that this is a distinct piece of IP, I don't > want to block the merging of the driver by leaving the conversation > hanging. > > There is still one thing I don't understand (which, amusingly, the > rockchip driver doesn't seem to suffer from): > >> +static void vsi_iommu_flush_tlb_all(struct iommu_domain *domain) >> +{ >> + struct vsi_iommu_domain *vsi_domain = to_vsi_domain(domain); >> + struct list_head *pos; >> + unsigned long flags; >> + >> + spin_lock_irqsave(&vsi_domain->lock, flags); >> + >> + list_for_each(pos, &vsi_domain->iommus) { >> + struct vsi_iommu *iommu; >> + int ret; >> + >> + iommu = list_entry(pos, struct vsi_iommu, node); >> + ret = pm_runtime_resume_and_get(iommu->dev); >> + if (ret < 0) >> + continue; >> + >> + spin_lock(&iommu->lock); >> + >> + writel(VSI_MMU_BIT_FLUSH, iommu->regs + VSI_MMU_FLUSH_BASE); >> + writel(0, iommu->regs + VSI_MMU_FLUSH_BASE); >> + >> + spin_unlock(&iommu->lock); >> + pm_runtime_put_autosuspend(iommu->dev); >> + } >> + >> + spin_unlock_irqrestore(&vsi_domain->lock, flags); >> +} > [...] > >> +static const struct iommu_ops vsi_iommu_ops = { >> + .identity_domain = &vsi_identity_domain, >> + .release_domain = &vsi_identity_domain, >> + .domain_alloc_paging = vsi_iommu_domain_alloc_paging, >> + .of_xlate = vsi_iommu_of_xlate, >> + .probe_device = vsi_iommu_probe_device, >> + .release_device = vsi_iommu_release_device, >> + .device_group = generic_single_device_group, >> + .owner = THIS_MODULE, >> + .default_domain_ops = &(const struct iommu_domain_ops) { >> + .attach_dev = vsi_iommu_attach_device, >> + .map_pages = vsi_iommu_map, >> + .unmap_pages = vsi_iommu_unmap, >> + .flush_iotlb_all = vsi_iommu_flush_tlb_all, > This has no callers and so your unmap routine appears to be broken. It is a leftover of previous attempt to allow video decoder to clean/flush the iommu by using a function from the API. Now it is using vsi_iommu_restore_ctx(). I while remove it in version 12. Thanks for your review. Benjamin > > Will