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<20200629071310.1557-5-chao.hao@mediatek.com> <0e9ceba8-0cc4-44a1-148c-1c9a6b3844ce@gmail.com> <1593514398.2581.7.camel@mbjsdccf07> From: Matthias Brugger Autocrypt: addr=matthias.bgg@gmail.com; prefer-encrypt=mutual; keydata= mQINBFP1zgUBEAC21D6hk7//0kOmsUrE3eZ55kjc9DmFPKIz6l4NggqwQjBNRHIMh04BbCMY fL3eT7ZsYV5nur7zctmJ+vbszoOASXUpfq8M+S5hU2w7sBaVk5rpH9yW8CUWz2+ZpQXPJcFa OhLZuSKB1F5JcvLbETRjNzNU7B3TdS2+zkgQQdEyt7Ij2HXGLJ2w+yG2GuR9/iyCJRf10Okq gTh//XESJZ8S6KlOWbLXRE+yfkKDXQx2Jr1XuVvM3zPqH5FMg8reRVFsQ+vI0b+OlyekT/Xe 0Hwvqkev95GG6x7yseJwI+2ydDH6M5O7fPKFW5mzAdDE2g/K9B4e2tYK6/rA7Fq4cqiAw1+u EgO44+eFgv082xtBez5WNkGn18vtw0LW3ESmKh19u6kEGoi0WZwslCNaGFrS4M7OH+aOJeqK fx5dIv2CEbxc6xnHY7dwkcHikTA4QdbdFeUSuj4YhIZ+0QlDVtS1QEXyvZbZky7ur9rHkZvP ZqlUsLJ2nOqsmahMTIQ8Mgx9SLEShWqD4kOF4zNfPJsgEMB49KbS2o9jxbGB+JKupjNddfxZ HlH1KF8QwCMZEYaTNogrVazuEJzx6JdRpR3sFda/0x5qjTadwIW6Cl9tkqe2h391dOGX1eOA 1ntn9O/39KqSrWNGvm+1raHK+Ev1yPtn0Wxn+0oy1tl67TxUjQARAQABtClNYXR0aGlhcyBC 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Content-Language: en-US Cc: devicetree@vger.kernel.org, FY Yang , wsd_upstream@mediatek.com, linux-kernel@vger.kernel.org, Evan Green , iommu@lists.linux-foundation.org, Rob Herring , linux-mediatek@lists.infradead.org, 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 30/06/2020 12:53, chao hao wrote: > On Mon, 2020-06-29 at 11:28 +0200, Matthias Brugger wrote: >> >> On 29/06/2020 09:13, Chao Hao wrote: >>> Add F_MMU_IN_ORDER_WR_EN and F_MMU_STANDARD_AXI_MODE_BIT definition >>> in MISC_CTRL register. >>> F_MMU_STANDARD_AXI_MODE_BIT: >>> If we set F_MMU_STANDARD_AXI_MODE_BIT(bit[3][19] = 0, not follow >>> standard AXI protocol), iommu will send urgent read command firstly >>> compare with normal read command to improve performance. >> >> Can you please help me to understand the phrase. Sorry I'm not a AXI specialist. >> Does this mean that you will send a 'urgent read command' which is not described >> in the specifications instead of a normal read command? > > ok. > iommu sends read command to next bus_node normally(we can name it to > cmd1), when cmd1 isn't handled by next bus_node, iommu has a urgent read > command is needed to be sent(we can name it to cmd2), iommu will send > cmd2 and replace cmd1. So cmd2 is handled by next bus_node firstly and > cmd2 will be handled secondly. > But for standard AXI protocol, it will ignore the priority of read > command and only be handled in order. So cmd2 is handled by next > bus_node after cmd1 is done. > Thanks. So I propose change this part of the commit message to something like: F_MMU_STANDARD_AXI_MODE_BIT: If we set F_MMU_STANDARD_AXI_MODE_EN_MASK (bit[3][19] = 0, not follow standard AXI protocol), the iommu will priorize sending of urgent read command over a normal read command. This improves the performance. >> >>> F_MMU_IN_ORDER_WR_EN: >>> If we set F_MMU_IN_ORDER_WR_EN(bit[1][17] = 0, out-of-order write), iommu >>> will re-order write command and send more higher priority write command >>> instead of sending write command in order. The feature be controlled >>> by OUT_ORDER_EN macro definition. F_MMU_IN_ORDER_WR_EN: If we set F_MMU_IN_ORDER_WR_EN_MASK (bit[1][17] = 0, out-of-order write), the iommu will re-order write commands and send the write command with higher priority. Otherwise the sending of write commands will be done in order. The feature is controlled by OUT_ORDER_WR_EN platform data flag. >>> >>> Cc: Matthias Brugger >>> Suggested-by: Yong Wu >>> Signed-off-by: Chao Hao >>> --- >>> drivers/iommu/mtk_iommu.c | 12 +++++++++++- >>> drivers/iommu/mtk_iommu.h | 1 + >>> 2 files changed, 12 insertions(+), 1 deletion(-) >>> >>> diff --git a/drivers/iommu/mtk_iommu.c b/drivers/iommu/mtk_iommu.c >>> index 8f81df6cbe51..67b46b5d83d9 100644 >>> --- a/drivers/iommu/mtk_iommu.c >>> +++ b/drivers/iommu/mtk_iommu.c >>> @@ -42,6 +42,9 @@ >>> #define F_INVLD_EN1 BIT(1) >>> >>> #define REG_MMU_MISC_CTRL 0x048 >>> +#define F_MMU_IN_ORDER_WR_EN (BIT(1) | BIT(17)) >>> +#define F_MMU_STANDARD_AXI_MODE_BIT (BIT(3) | BIT(19)) >> >> Wouldn't it make more sense to name it F_MMU_STANDARD_AXI_MODE_EN? > ok, you are right. > 1'b1: follow standard axi protocol > What about F_MMU_IN_ORDER_WR_EN_MASK F_MMU_STANDARD_AXI_MODE_EN_MASK Background is that we have to set/unset two bits to enable or disable the feature, so it's a mask we have to apply to the register. Regards, Matthias >> >>> + >>> #define REG_MMU_DCM_DIS 0x050 >>> >>> #define REG_MMU_CTRL_REG 0x110 >>> @@ -574,10 +577,17 @@ static int mtk_iommu_hw_init(const struct mtk_iommu_data *data) >>> } >>> writel_relaxed(0, data->base + REG_MMU_DCM_DIS); >>> >>> + regval = readl_relaxed(data->base + REG_MMU_MISC_CTRL); >> >> We only need to read regval in the else branch. > > ok, I got it. thanks > >> >>> if (MTK_IOMMU_HAS_FLAG(data->plat_data, RESET_AXI)) { >>> /* The register is called STANDARD_AXI_MODE in this case */ >>> - writel_relaxed(0, data->base + REG_MMU_MISC_CTRL); >>> + regval = 0; >>> + } else { >>> + /* For mm_iommu, it can improve performance by the setting */ >>> + regval &= ~F_MMU_STANDARD_AXI_MODE_BIT; >>> + if (MTK_IOMMU_HAS_FLAG(data->plat_data, OUT_ORDER_EN)) >>> + regval &= ~F_MMU_IN_ORDER_WR_EN; >>> } >>> + writel_relaxed(regval, data->base + REG_MMU_MISC_CTRL); >>> >>> if (devm_request_irq(data->dev, data->irq, mtk_iommu_isr, 0, >>> dev_name(data->dev), (void *)data)) { >>> diff --git a/drivers/iommu/mtk_iommu.h b/drivers/iommu/mtk_iommu.h >>> index 7cc39f729263..4b780b651ef4 100644 >>> --- a/drivers/iommu/mtk_iommu.h >>> +++ b/drivers/iommu/mtk_iommu.h >>> @@ -22,6 +22,7 @@ >>> #define HAS_BCLK BIT(1) >>> #define HAS_VLD_PA_RNG BIT(2) >>> #define RESET_AXI BIT(3) >>> +#define OUT_ORDER_EN BIT(4) >> >> Maybe something like OUT_ORDER_WR_EN, to make clear that it's about the the >> write path. >> > ok, thanks for your advice. > >>> >>> #define MTK_IOMMU_HAS_FLAG(pdata, _x) \ >>> ((((pdata)->flags) & (_x)) == (_x)) >>> > _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu