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

AngeloGioacchino Del Regno
2025-03-06T09:47:50Z

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.

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);
}

Cheers,
Angelo

> + } else {
> + /* only MMIO access, no need to check mminfro_offset */
> + cmdq_pkt_assign(cmdq_pkt, 0, CMDQ_ADDR_HIGH(cmdq_reg->pa_base));
> + if (mask == GENMASK(31, 0))
> + cmdq_pkt_write_s_value(cmdq_pkt, CMDQ_THR_SPR_IDX0,
> + CMDQ_ADDR_LOW(offset), value);
> + else
> + cmdq_pkt_write_s_mask_value(cmdq_pkt, CMDQ_THR_SPR_IDX0,
> + CMDQ_ADDR_LOW(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));
> else
> #endif
> writel(value, regs + offset);
> @@ -85,8 +108,7 @@ 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));
> else
> #endif
> writel_relaxed(value, regs + offset);
> @@ -98,8 +120,7 @@ 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);