Re: [PATCH v4 7/8] drm/mediatek: Add programming flow for unsupported subsys ID hardware

["Jason-JH Lin (林睿祥)" <Jason-JH.Lin@mediatek.com>]

On Thu, 2025-03-06 at 10:47 +0100, AngeloGioacchino Del Regno wrote:
> 
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> 
> 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@mediatek.com>
> > Reviewed-by: CK Hu <ck.hu@mediatek.com>
> > ---
> >   drivers/gpu/drm/mediatek/mtk_ddp_comp.c | 33
> > ++++++++++++++++++++-----
> >   1 file changed, 27 insertions(+), 6 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/mediatek/mtk_ddp_comp.c
> > b/drivers/gpu/drm/mediatek/mtk_ddp_comp.c
> > index edc6417639e6..219d67735a54 100644
> > --- a/drivers/gpu/drm/mediatek/mtk_ddp_comp.c
> > +++ b/drivers/gpu/drm/mediatek/mtk_ddp_comp.c
> > @@ -66,14 +66,37 @@ struct mtk_ddp_comp_dev {
> >       struct cmdq_client_reg cmdq_reg;
> >   };
> > 
> > +#if IS_REACHABLE(CONFIG_MTK_CMDQ)
> > +static void 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) {
> > +             if (mask == GENMASK(31, 0))
> > +                     cmdq_pkt_write(cmdq_pkt, cmdq_reg->subsys,
> > offset, value);
> > +             else
> > +                     cmdq_pkt_write_mask(cmdq_pkt, cmdq_reg-
> > >subsys, offset, value, mask);
> 
> Sorry but this is pointless, really...
> 
> Function cmdq_pkt_write_mask() in mtk-cmdq-helper is doing:
> 
>         if (mask != GENMASK(31, 0)) {
>                 err = cmdq_pkt_mask(pkt, mask);
>                 if (err < 0)
>                         return err;
> 
>                 offset_mask |= CMDQ_WRITE_ENABLE_MASK;
>         }
>         return cmdq_pkt_write(pkt, subsys, offset_mask, value);
> 
> here you're doing the exact inverse check.
> 

Oh, I didn't notice that it was redundant. Thanks.

> At this point you can just do:
> 
> static int mtk_ddp_write_cmdq_pkt(struct cmdq_pkt *cmdq_pkt, struct
> cmdq_client_reg
> *cmdq_reg,
>                                   u16 offset, u32 value, u32 mask)
> {
>         u16 gce_offset = cmdq_reg->offset + offset;
> 
>         if (cmdq_reg->subsys != CMDQ_SUBSYS_INVALID)
>                 return cmdq_pkt_write_mask(pkt, cmdq_reg->subsys,
> gce_offset, value, mask);
> 
>         return cmdq_pkt_write_mask_pa(cmdq_pkt, cmdq_reg->pa_base,
> gce_offset, value, mask);
> }
> 

I'll change like this, Thanks!

Regards,
Jason-JH Lin

> Cheers,
> Angelo