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X-UUID: 64a3eedf2d8f47b0872f0ccf7b813178-20200703 Received: from mtkcas06.mediatek.inc [(172.21.101.30)] by mailgw02.mediatek.com (envelope-from ) (Cellopoint E-mail Firewall v4.1.10 Build 0809 with TLS) with ESMTP id 901121176; Fri, 03 Jul 2020 10:39:16 +0800 Received: from mtkcas08.mediatek.inc (172.21.101.126) by mtkmbs01n2.mediatek.inc (172.21.101.79) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Fri, 3 Jul 2020 10:39:13 +0800 Received: from [10.15.20.246] (10.15.20.246) by mtkcas08.mediatek.inc (172.21.101.73) with Microsoft SMTP Server id 15.0.1497.2 via Frontend Transport; Fri, 3 Jul 2020 10:39:13 +0800 Message-ID: <1593743885.22738.2.camel@mbjsdccf07> Subject: Re: [PATCH v5 04/10] iommu/mediatek: Setting MISC_CTRL register From: chao hao To: Matthias Brugger Date: Fri, 3 Jul 2020 10:38:05 +0800 In-Reply-To: References: <20200629071310.1557-1-chao.hao@mediatek.com> <20200629071310.1557-5-chao.hao@mediatek.com> <0e9ceba8-0cc4-44a1-148c-1c9a6b3844ce@gmail.com> <1593514398.2581.7.camel@mbjsdccf07> X-Mailer: Evolution 3.10.4-0ubuntu2 MIME-Version: 1.0 X-TM-SNTS-SMTP: 3EE8F4A8513308CBFB404D0FBB6A79928236E6EF658504C0F5CE61D2EE0CAC8E2000:8 X-MTK: N Cc: devicetree@vger.kernel.org, FY Yang , wsd_upstream@mediatek.com, linux-kernel@vger.kernel.org, Evan Green , Chao Hao , 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 Wed, 2020-07-01 at 16:58 +0200, Matthias Brugger wrote: > > 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. > ok, thanks > >> > >>> 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. > ok, thanks for your advice > 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