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Mon, 25 Oct 2021 12:03:53 +0800 Message-ID: Subject: Re: [PATCH v3 13/33] iommu/mediatek: Remove the power status checking in tlb flush all From: Yong Wu To: Dafna Hirschfeld , Joerg Roedel , Rob Herring , Matthias Brugger , Will Deacon , Robin Murphy Date: Mon, 25 Oct 2021 12:03:53 +0800 In-Reply-To: <6cff0b97-b861-e02d-e76f-2510c962c452@collabora.com> References: <20210923115840.17813-1-yong.wu@mediatek.com> <20210923115840.17813-14-yong.wu@mediatek.com> <6cff0b97-b861-e02d-e76f-2510c962c452@collabora.com> X-Mailer: Evolution 3.28.5-0ubuntu0.18.04.2 MIME-Version: 1.0 X-MTK: N Cc: youlin.pei@mediatek.com, devicetree@vger.kernel.org, Collabora Kernel ML , srv_heupstream@mediatek.com, Krzysztof Kozlowski , linux-kernel@vger.kernel.org, yen-chang.chen@mediatek.com, chao.hao@mediatek.com, iommu@lists.linux-foundation.org, linux-mediatek@lists.infradead.org, Hsin-Yi Wang , anan.sun@mediatek.com, linux-arm-kernel@lists.infradead.org X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Development issues for Linux IOMMU support List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: iommu-bounces@lists.linux-foundation.org Sender: "iommu" On Fri, 2021-10-22 at 16:03 +0200, Dafna Hirschfeld wrote: > Hi > > > On 23.09.21 13:58, Yong Wu wrote: > > To simplify the code, Remove the power status checking in the > > tlb_flush_all, remove this: > > if (pm_runtime_get_if_in_use(data->dev) <= 0) > > continue; > > > > After this patch, the mtk_iommu_tlb_flush_all will be called from > > a) isr > > b) pm runtime resume callback > > c) tlb flush range fail case > > d) iommu_create_device_direct_mappings > > -> iommu_flush_iotlb_all > > In first three cases, the power and clock always are enabled; d) is > > direct > > Regarding case "c) tlb flush range fail case", I found out that this > often happens when the iommu is used while it is runtime suspended. Which SoC and branch are you testing on? > For example the mtk-vcodec encoder driver calls > "pm_runtime_resume_and_get" only when it starts > streaming but > buffers allocation is done in 'v4l2_reqbufs' before > "pm_runtime_resume_and_get" is called This is the case I tried to fix in [14/33]. pm_runtime_get_if_in_use should return when the iommu device's pm is not active when vcodec allocate buffer before pm_runtime_resume_and get. Do you have the devicelink patchset in your branch? if not, the vcodec should call mtk_smi_larb_get to enable the power/clock for larbs, then the iommu's device is active via devicelink between smi and iommu device. > and then I see the warning "Partial TLB flush timed out, falling back > to full flush" > I am not sure how to fix that issue, but it seems that case 'c)' > might indicate that > power and clock are actually not enabled. > > > mapping, the tlb flush is unnecessay since we already have > > tlb_flush_all > > in the pm_runtime_resume callback. When the iommu's power status is > > changed to active, the tlb always is clean. > > > > In addition, there still are 2 reasons that don't add PM status > > checking > > in the tlb flush all: > > a) Write tlb flush all register also is ok even though the HW has > > no > > power and clocks. Write ignore. > > b) pm_runtime_get_if_in_use(m4udev) is 0 when the tlb_flush_all > > is called frm pm_runtime_resume cb. From this point, we can not add > > this code above in this tlb_flush_all. > > > > Signed-off-by: Yong Wu > > --- > > drivers/iommu/mtk_iommu.c | 20 +++++++------------- > > 1 file changed, 7 insertions(+), 13 deletions(-) > > > > diff --git a/drivers/iommu/mtk_iommu.c b/drivers/iommu/mtk_iommu.c > > index e9e94944ed91..4a33b6c6b1db 100644 > > --- a/drivers/iommu/mtk_iommu.c > > +++ b/drivers/iommu/mtk_iommu.c > > @@ -204,10 +204,14 @@ static struct mtk_iommu_domain > > *to_mtk_domain(struct iommu_domain *dom) > > return container_of(dom, struct mtk_iommu_domain, domain); > > } > > > > -static void mtk_iommu_tlb_do_flush_all(struct mtk_iommu_data > > *data) > > +static void mtk_iommu_tlb_flush_all(struct mtk_iommu_data *data) > > { > > unsigned long flags; > > > > + /* > > + * No need get power status since the HW PM status nearly is > > active > > + * when entering here. > > + */ > > spin_lock_irqsave(&data->tlb_lock, flags); > > writel_relaxed(F_INVLD_EN1 | F_INVLD_EN0, > > data->base + data->plat_data->inv_sel_reg); > > @@ -216,16 +220,6 @@ static void mtk_iommu_tlb_do_flush_all(struct > > mtk_iommu_data *data) > > spin_unlock_irqrestore(&data->tlb_lock, flags); > > } > > > > -static void mtk_iommu_tlb_flush_all(struct mtk_iommu_data *data) > > -{ > > - if (pm_runtime_get_if_in_use(data->dev) <= 0) > > - return; > > - > > - mtk_iommu_tlb_do_flush_all(data); > > - > > - pm_runtime_put(data->dev); > > -} > > - > > static void mtk_iommu_tlb_flush_range_sync(unsigned long iova, > > size_t size, > > struct mtk_iommu_data *data) > > { > > @@ -263,7 +257,7 @@ static void > > mtk_iommu_tlb_flush_range_sync(unsigned long iova, size_t size, > > if (ret) { > > dev_warn(data->dev, > > "Partial TLB flush timed out, falling > > back to full flush\n"); > > - mtk_iommu_tlb_do_flush_all(data); > > + mtk_iommu_tlb_flush_all(data); > > } > > > > if (has_pm) > > @@ -993,7 +987,7 @@ static int __maybe_unused > > mtk_iommu_runtime_resume(struct device *dev) > > * > > * Thus, Make sure the tlb always is clean after each PM > > resume. > > */ > > - mtk_iommu_tlb_do_flush_all(data); > > + mtk_iommu_tlb_flush_all(data); > > > > /* > > * Uppon first resume, only enable the clk and return, since > > the values of the > > _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu