linux-kernel - Re: [PATCH v4 6/8] soc: mediatek: Add programming flow for unsupported subsys ID hardware

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Message-ID: <c52b132b-fc08-4d1c-8276-1771f7457014@collabora.com>
Date: Tue, 4 Mar 2025 10:41:43 +0100
From: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
To: Jason-JH Lin <jason-jh.lin@...iatek.com>, Rob Herring <robh@...nel.org>,
 Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley
 <conor+dt@...nel.org>, Jassi Brar <jassisinghbrar@...il.com>,
 Chun-Kuang Hu <chunkuang.hu@...nel.org>,
 Mauro Carvalho Chehab <mchehab@...nel.org>
Cc: Matthias Brugger <matthias.bgg@...il.com>,
 Nancy Lin <nancy.lin@...iatek.com>, Singo Chang <singo.chang@...iatek.com>,
 Moudy Ho <moudy.ho@...iatek.com>, Xavier Chang <xavier.chang@...iatek.com>,
 Xiandong Wang <xiandong.wang@...iatek.com>,
 Sirius Wang <sirius.wang@...iatek.com>, Fei Shao <fshao@...omium.org>,
 Pin-yen Lin <treapking@...omium.org>,
 Project_Global_Chrome_Upstream_Group@...iatek.com,
 devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
 dri-devel@...ts.freedesktop.org, linux-mediatek@...ts.infradead.org,
 linux-arm-kernel@...ts.infradead.org, linux-media@...r.kernel.org
Subject: Re: [PATCH v4 6/8] soc: mediatek: Add programming flow for
 unsupported subsys ID hardware

Il 18/02/25 06:41, Jason-JH Lin ha scritto:
> To support hardware without subsys IDs on new SoCs, add a programming
> flow that checks whether the subsys ID is valid. If the subsys ID is
> invalid, the flow will call 2 alternative CMDQ APIs:
> cmdq_pkt_assign() and cmdq_pkt_write_s_value() to achieve the same
> functionality.
> 
> Signed-off-by: Jason-JH Lin <jason-jh.lin@...iatek.com>
> ---
>   drivers/soc/mediatek/mtk-mmsys.c | 14 +++++++++++---
>   drivers/soc/mediatek/mtk-mutex.c | 11 +++++++++--
>   2 files changed, 20 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/soc/mediatek/mtk-mmsys.c b/drivers/soc/mediatek/mtk-mmsys.c
> index bb4639ca0b8c..ce949b863b05 100644
> --- a/drivers/soc/mediatek/mtk-mmsys.c
> +++ b/drivers/soc/mediatek/mtk-mmsys.c
> @@ -167,9 +167,17 @@ static void mtk_mmsys_update_bits(struct mtk_mmsys *mmsys, u32 offset, u32 mask,
>   	u32 tmp;
>   
>   	if (mmsys->cmdq_base.size && cmdq_pkt) {
> -		ret = cmdq_pkt_write_mask(cmdq_pkt, mmsys->cmdq_base.subsys,
> -					  mmsys->cmdq_base.offset + offset, val,
> -					  mask);
> +		offset += mmsys->cmdq_base.offset;
> +		if (mmsys->cmdq_base.subsys != CMDQ_SUBSYS_INVALID) {

You're still anyway passing the subsys to cmdq_pkt_write_mask(), right?!
Why don't you just handle this in cmdq_pkt_write_mask() then? ;-)

I can see this pattern being repeated over and over in both drm/mediatek and MDP3
drivers, and it's not necessary to duplicate this many times when you can write it
just once.

Would've also been faster for you to implement... :-D

Cheers,
Angelo

> +			ret = cmdq_pkt_write_mask(cmdq_pkt, mmsys->cmdq_base.subsys,
> +						  offset, val, mask);
> +		} else {
> +			/* only MMIO access, no need to check mminfro_offset */
> +			ret = cmdq_pkt_assign(cmdq_pkt, CMDQ_THR_SPR_IDX0,
> +					      CMDQ_ADDR_HIGH(mmsys->cmdq_base.pa_base));
> +			ret |= cmdq_pkt_write_s_mask_value(cmdq_pkt, CMDQ_THR_SPR_IDX0,
> +							   CMDQ_ADDR_LOW(offset), val, mask);
> +		}
>   		if (ret)
>   			pr_debug("CMDQ unavailable: using CPU write\n");
>   		else
> diff --git a/drivers/soc/mediatek/mtk-mutex.c b/drivers/soc/mediatek/mtk-mutex.c
> index 5250c1d702eb..3788b16efbf4 100644
> --- a/drivers/soc/mediatek/mtk-mutex.c
> +++ b/drivers/soc/mediatek/mtk-mutex.c
> @@ -963,6 +963,7 @@ int mtk_mutex_enable_by_cmdq(struct mtk_mutex *mutex, void *pkt)
>   	struct mtk_mutex_ctx *mtx = container_of(mutex, struct mtk_mutex_ctx,
>   						 mutex[mutex->id]);
>   	struct cmdq_pkt *cmdq_pkt = (struct cmdq_pkt *)pkt;
> +	dma_addr_t en_addr = mtx->addr + DISP_REG_MUTEX_EN(mutex->id);
>   
>   	WARN_ON(&mtx->mutex[mutex->id] != mutex);
>   
> @@ -971,8 +972,14 @@ int mtk_mutex_enable_by_cmdq(struct mtk_mutex *mutex, void *pkt)
>   		return -ENODEV;
>   	}
>   
> -	cmdq_pkt_write(cmdq_pkt, mtx->cmdq_reg.subsys,
> -		       mtx->addr + DISP_REG_MUTEX_EN(mutex->id), 1);
> +	if (mtx->cmdq_reg.subsys != CMDQ_SUBSYS_INVALID) {
> +		cmdq_pkt_write(cmdq_pkt, mtx->cmdq_reg.subsys, en_addr, 1);
> +	} else {
> +		/* only MMIO access, no need to check mminfro_offset */
> +		cmdq_pkt_assign(cmdq_pkt, CMDQ_THR_SPR_IDX0, CMDQ_ADDR_HIGH(en_addr));
> +		cmdq_pkt_write_s_value(cmdq_pkt, CMDQ_THR_SPR_IDX0, CMDQ_ADDR_LOW(en_addr), 1);
> +	}
> +
>   	return 0;
>   }
>   EXPORT_SYMBOL_GPL(mtk_mutex_enable_by_cmdq);