Re: [PATCH v7 13/20] drm/mediatek: Add programming flow for unsupported subsys ID hardware

["CK Hu (胡俊光)" <ck.hu@mediatek.com>]

On Wed, 2025-08-27 at 19:37 +0800, Jason-JH Lin wrote:
> 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 valid, the flow will call cmdq_pkt_write_subsys()
> instead of the original cmdq_pkt_write().
> 
> If the subsys ID is invalid, the flow will call cmdq_pkt_write_mask_pa()
> to achieve the same functionality.
> 
> Signed-off-by: Jason-JH Lin <jason-jh.lin@mediatek.com>
> ---
>  drivers/gpu/drm/mediatek/mtk_ddp_comp.c | 24 ++++++++++++++++++------
>  1 file changed, 18 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/gpu/drm/mediatek/mtk_ddp_comp.c b/drivers/gpu/drm/mediatek/mtk_ddp_comp.c
> index ac6620e10262..d902a65e1232 100644
> --- a/drivers/gpu/drm/mediatek/mtk_ddp_comp.c
> +++ b/drivers/gpu/drm/mediatek/mtk_ddp_comp.c
> @@ -66,14 +66,28 @@ struct mtk_ddp_comp_dev {
>  	struct cmdq_client_reg cmdq_reg;
>  };
>  
> +#if IS_REACHABLE(CONFIG_MTK_CMDQ)
> +static int mtk_ddp_write_cmdq_pkt(struct cmdq_pkt *cmdq_pkt, struct cmdq_client_reg *cmdq_reg,
> +				  unsigned int offset, unsigned int value, unsigned int mask)
> +{
> +	offset += cmdq_reg->offset;
> +
> +	if (cmdq_reg->subsys != CMDQ_SUBSYS_INVALID)
> +		return cmdq_pkt_write_mask_subsys(cmdq_pkt, cmdq_reg->subsys, cmdq_reg->pa_base,
> +						  offset, value, mask);
> +	else /* only MMIO access, no need to check mminfro_offset */
> +		return cmdq_pkt_write_mask_pa(cmdq_pkt, cmdq_reg->subsys, cmdq_reg->pa_base,
> +					      offset, value, mask);
> +}
> +#endif
> +
>  void mtk_ddp_write(struct cmdq_pkt *cmdq_pkt, unsigned int value,
>  		   struct cmdq_client_reg *cmdq_reg, void __iomem *regs,
>  		   unsigned int offset)
>  {
>  #if IS_REACHABLE(CONFIG_MTK_CMDQ)
>  	if (cmdq_pkt)
> -		cmdq_pkt_write(cmdq_pkt, cmdq_reg->subsys,
> -			       cmdq_reg->offset + offset, value);
> +		mtk_ddp_write_cmdq_pkt(cmdq_pkt, cmdq_reg, offset, value, GENMASK(31, 0));

mtk_ddp_write() is no mask and cmdq provide no mask api, so

if (cmdq_reg->subsys != CMDQ_SUBSYS_INVALID)
	cmdq_pkt_write_subsys();
else
	cmdq_pkt_write_pa();

>  	else
>  #endif
>  		writel(value, regs + offset);
> @@ -85,8 +99,7 @@ void mtk_ddp_write_relaxed(struct cmdq_pkt *cmdq_pkt, unsigned int value,
>  {
>  #if IS_REACHABLE(CONFIG_MTK_CMDQ)
>  	if (cmdq_pkt)
> -		cmdq_pkt_write(cmdq_pkt, cmdq_reg->subsys,
> -			       cmdq_reg->offset + offset, value);
> +		mtk_ddp_write_cmdq_pkt(cmdq_pkt, cmdq_reg, offset, value, GENMASK(31, 0));

Ditto.

Regards,
CK

>  	else
>  #endif
>  		writel_relaxed(value, regs + offset);
> @@ -98,8 +111,7 @@ void mtk_ddp_write_mask(struct cmdq_pkt *cmdq_pkt, unsigned int value,
>  {
>  #if IS_REACHABLE(CONFIG_MTK_CMDQ)
>  	if (cmdq_pkt) {
> -		cmdq_pkt_write_mask(cmdq_pkt, cmdq_reg->subsys,
> -				    cmdq_reg->offset + offset, value, mask);
> +		mtk_ddp_write_cmdq_pkt(cmdq_pkt, cmdq_reg, offset, value, mask);
>  	} else {
>  #endif
>  		u32 tmp = readl(regs + offset);