linux-kernel - Re: [PATCH 2/3] iommu/mediatek: Add a flag DL_WITH_MULTI

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Message-ID: <2d179e08-c6f4-4e0d-8d2c-10c643e96d5e@gmail.com>
Date: Thu, 7 Aug 2025 17:24:28 +0200
From: Matthias Brugger <matthias.bgg@...il.com>
To: zhengnan chen <zhengnan.chen@...iatek.com>, Yong Wu
 <yong.wu@...iatek.com>, Joerg Roedel <joro@...tes.org>,
 Will Deacon <will@...nel.org>, Robin Murphy <robin.murphy@....com>,
 Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>,
 Conor Dooley <conor+dt@...nel.org>, Matthias Brugger
 <matthias.bgg@...il.com>,
 AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
Cc: iommu@...ts.linux.dev, linux-mediatek@...ts.infradead.org,
 devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-arm-kernel@...ts.infradead.org,
 Project_Global_Chrome_Upstream_Group@...iatek.com
Subject: Re: [PATCH 2/3] iommu/mediatek: Add a flag DL_WITH_MULTI_LARB

On 07/08/2025 11:57, zhengnan chen wrote:
> From: "zhengnan chen" <zhengnan.chen@...iatek.com>
> 
> Add DL_WITH_MULTI_LARB flag to support the HW which connect with
> multiple larbs. Prepare for mt8189. In mt8189, the display connect
> with larb1 and larb2 at the same time. Thus, we should add link
> between disp-dev with these two larbs.
> 
> Signed-off-by: zhengnan chen <zhengnan.chen@...iatek.com>

Reviewed-by: Matthias Brugger <matthias.bgg@...il.com>

> ---
>   drivers/iommu/mtk_iommu.c | 56 ++++++++++++++++++++++++++++++---------
>   1 file changed, 43 insertions(+), 13 deletions(-)
> 
> diff --git a/drivers/iommu/mtk_iommu.c b/drivers/iommu/mtk_iommu.c
> index 0e0285348d2b..7af47c59b10b 100644
> --- a/drivers/iommu/mtk_iommu.c
> +++ b/drivers/iommu/mtk_iommu.c
> @@ -147,6 +147,7 @@
>   #define TF_PORT_TO_ADDR_MT8173		BIT(18)
>   #define INT_ID_PORT_WIDTH_6		BIT(19)
>   #define CFG_IFA_MASTER_IN_ATF		BIT(20)
> +#define DL_WITH_MULTI_LARB		BIT(21)
>   
>   #define MTK_IOMMU_HAS_FLAG_MASK(pdata, _x, mask)	\
>   				((((pdata)->flags) & (mask)) == (_x))
> @@ -865,6 +866,7 @@ static struct iommu_device *mtk_iommu_probe_device(struct device *dev)
>   	struct mtk_iommu_data *data = dev_iommu_priv_get(dev);
>   	struct device_link *link;
>   	struct device *larbdev;
> +	unsigned long larbid_msk = 0;
>   	unsigned int larbid, larbidx, i;
>   
>   	if (!MTK_IOMMU_IS_TYPE(data->plat_data, MTK_IOMMU_TYPE_MM))
> @@ -872,30 +874,50 @@ static struct iommu_device *mtk_iommu_probe_device(struct device *dev)
>   
>   	/*
>   	 * Link the consumer device with the smi-larb device(supplier).
> -	 * The device that connects with each a larb is a independent HW.
> -	 * All the ports in each a device should be in the same larbs.
> +	 * w/DL_WITH_MULTI_LARB: the master may connect with multi larbs,
> +	 * we should create device link with each larb.
> +	 * w/o DL_WITH_MULTI_LARB: the master must connect with one larb,
> +	 * otherwise fail.
>   	 */
>   	larbid = MTK_M4U_TO_LARB(fwspec->ids[0]);
>   	if (larbid >= MTK_LARB_NR_MAX)
>   		return ERR_PTR(-EINVAL);
>   
> +	larbid_msk |= BIT(larbid);
> +
>   	for (i = 1; i < fwspec->num_ids; i++) {
>   		larbidx = MTK_M4U_TO_LARB(fwspec->ids[i]);
> -		if (larbid != larbidx) {
> +		if (MTK_IOMMU_HAS_FLAG(data->plat_data, DL_WITH_MULTI_LARB)) {
> +			larbid_msk |= BIT(larbidx);
> +		} else if (larbid != larbidx) {
>   			dev_err(dev, "Can only use one larb. Fail@...b%d-%d.\n",
>   				larbid, larbidx);
>   			return ERR_PTR(-EINVAL);
>   		}
>   	}
> -	larbdev = data->larb_imu[larbid].dev;
> -	if (!larbdev)
> -		return ERR_PTR(-EINVAL);
>   
> -	link = device_link_add(dev, larbdev,
> -			       DL_FLAG_PM_RUNTIME | DL_FLAG_STATELESS);
> -	if (!link)
> -		dev_err(dev, "Unable to link %s\n", dev_name(larbdev));
> +	for_each_set_bit(larbid, &larbid_msk, 32) {
> +		larbdev = data->larb_imu[larbid].dev;
> +		if (!larbdev)
> +			return ERR_PTR(-EINVAL);
> +
> +		link = device_link_add(dev, larbdev,
> +				       DL_FLAG_PM_RUNTIME | DL_FLAG_STATELESS);
> +		if (!link) {
> +			dev_err(dev, "Unable to link %s\n", dev_name(larbdev));
> +			goto link_remove;
> +		}
> +	}
> +
>   	return &data->iommu;
> +
> +link_remove:
> +	for_each_set_bit(i, &larbid_msk, larbid) {
> +		larbdev = data->larb_imu[i].dev;
> +		device_link_remove(dev, larbdev);
> +	}
> +
> +	return ERR_PTR(-ENODEV);
>   }
>   
>   static void mtk_iommu_release_device(struct device *dev)
> @@ -903,11 +925,19 @@ static void mtk_iommu_release_device(struct device *dev)
>   	struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev);
>   	struct mtk_iommu_data *data;
>   	struct device *larbdev;
> -	unsigned int larbid;
> +	unsigned int larbid, i;
> +	unsigned long larbid_msk = 0;
>   
>   	data = dev_iommu_priv_get(dev);
> -	if (MTK_IOMMU_IS_TYPE(data->plat_data, MTK_IOMMU_TYPE_MM)) {
> -		larbid = MTK_M4U_TO_LARB(fwspec->ids[0]);
> +	if (!MTK_IOMMU_IS_TYPE(data->plat_data, MTK_IOMMU_TYPE_MM))
> +		return;
> +
> +	for (i = 0; i < fwspec->num_ids; i++) {
> +		larbid = MTK_M4U_TO_LARB(fwspec->ids[i]);
> +		larbid_msk |= BIT(larbid);
> +	}
> +
> +	for_each_set_bit(larbid, &larbid_msk, 32) {
>   		larbdev = data->larb_imu[larbid].dev;
>   		device_link_remove(dev, larbdev);
>   	}