Re: [PATCH v2 12/14] soc: mediatek: cmdq: add loop function

Dennis-YC Hsieh
2019-12-12T01:37:42Z

Hi CK,

On Wed, 2019-12-11 at 09:48 +0800, CK Hu wrote:
> Hi, Dennis:
>
> On Wed, 2019-11-27 at 09:58 +0800, Dennis YC Hsieh wrote:
> > Add finalize loop function in cmdq helper functions which loop whole pkt
> > in gce hardware thread without cpu operation.
> >
> > Signed-off-by: Dennis YC Hsieh <dennis-yc.hsieh@mediatek.com>
> > ---
> > drivers/soc/mediatek/mtk-cmdq-helper.c | 22 ++++++++++++++++++++++
> > include/linux/soc/mediatek/mtk-cmdq.h | 8 ++++++++
> > 2 files changed, 30 insertions(+)
> >
> > diff --git a/drivers/soc/mediatek/mtk-cmdq-helper.c b/drivers/soc/mediatek/mtk-cmdq-helper.c
> > index 38e0c13e1922..10a9b4481e58 100644
> > --- a/drivers/soc/mediatek/mtk-cmdq-helper.c
> > +++ b/drivers/soc/mediatek/mtk-cmdq-helper.c
> > @@ -414,6 +414,28 @@ int cmdq_pkt_finalize(struct cmdq_pkt *pkt)
> > }
> > EXPORT_SYMBOL(cmdq_pkt_finalize);
> >
> > +int cmdq_pkt_finalize_loop(struct cmdq_pkt *pkt)
> > +{
> > + struct cmdq_client *cl = pkt->cl;
> > + struct cmdq_instruction inst = { {0} };
> > + int err;
> > +
> > + /* insert EOC and generate IRQ for each command iteration */
> > + inst.op = CMDQ_CODE_EOC;
> > + err = cmdq_pkt_append_command(pkt, inst);
> > + if (err < 0)
> > + return err;
>
> It looks like you want a pkt execute command repeatedly, but why do you
> repeatedly trigger IRQ? This IRQ would do nothing because this pkt would
> never finish.
>

see following section

> > +
> > + /* JUMP abaolute to begin */
> > + inst.op = CMDQ_CODE_JUMP;
> > + inst.offset = 1;
> > + inst.value = pkt->pa_base >> cmdq_mbox_shift(cl->chan);
> > + err = cmdq_pkt_append_command(pkt, inst);
>
> Why not just export this function as cmdq_pkt_jump()? Let client decide
> where to jump would be more flexible.
>
> Regards,
> CK
>

ok, I will remove this part and expose cmdq_pkt_jump()

Regards,
Dennis

> > +
> > + return err;
> > +}
> > +EXPORT_SYMBOL(cmdq_pkt_finalize_loop);
> > +
> > static void cmdq_pkt_flush_async_cb(struct cmdq_cb_data data)
> > {
> > struct cmdq_pkt *pkt = (struct cmdq_pkt *)data.data;
> > diff --git a/include/linux/soc/mediatek/mtk-cmdq.h b/include/linux/soc/mediatek/mtk-cmdq.h
> > index 998bc90f9da9..d15d8c941992 100644
> > --- a/include/linux/soc/mediatek/mtk-cmdq.h
> > +++ b/include/linux/soc/mediatek/mtk-cmdq.h
> > @@ -212,6 +212,14 @@ int cmdq_pkt_assign(struct cmdq_pkt *pkt, u16 reg_idx, u32 value);
> > */
> > int cmdq_pkt_finalize(struct cmdq_pkt *pkt);
> >
> > +/**
> > + * cmdq_pkt_finalize_loop() - Append EOC and jump command to loop pkt.
> > + * @pkt: the CMDQ packet
> > + *
> > + * Return: 0 for success; else the error code is returned
> > + */
> > +int cmdq_pkt_finalize_loop(struct cmdq_pkt *pkt);
> > +
> > /**
> > * cmdq_pkt_flush_async() - trigger CMDQ to asynchronously execute the CMDQ
> > * packet and call back at the end of done packet