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Date: Tue, 23 Jun 2020 00:12:52 +0800
From: Dennis-YC Hsieh <dennis-yc.hsieh@...iatek.com>
To: Matthias Brugger <matthias.bgg@...il.com>
CC: Philipp Zabel <p.zabel@...gutronix.de>,
David Airlie <airlied@...ux.ie>,
Daniel Vetter <daniel@...ll.ch>, CK Hu <ck.hu@...iatek.com>,
Bibby Hsieh <bibby.hsieh@...iatek.com>,
Houlong Wei <houlong.wei@...iatek.com>,
<dri-devel@...ts.freedesktop.org>,
<linux-arm-kernel@...ts.infradead.org>,
<linux-mediatek@...ts.infradead.org>,
<linux-kernel@...r.kernel.org>, <wsd_upstream@...iatek.com>,
HS Liao <hs.liao@...iatek.com>
Subject: Re: [PATCH v1 03/11] soc: mediatek: cmdq: add write_s function
Hi Matthias,
On Mon, 2020-06-22 at 17:54 +0200, Matthias Brugger wrote:
>
> On 22/06/2020 17:36, Dennis-YC Hsieh wrote:
> > Hi Matthias,
> >
> > thanks for your comment.
> >
> > On Mon, 2020-06-22 at 13:07 +0200, Matthias Brugger wrote:
> >>
> >> On 21/06/2020 16:18, Dennis YC Hsieh wrote:
> >>> add write_s function in cmdq helper functions which
> >>> writes value contains in internal register to address
> >>> with large dma access support.
> >>>
> >>> Signed-off-by: Dennis YC Hsieh <dennis-yc.hsieh@...iatek.com>
> >>> ---
> >>> drivers/soc/mediatek/mtk-cmdq-helper.c | 19 +++++++++++++++++++
> >>> include/linux/mailbox/mtk-cmdq-mailbox.h | 1 +
> >>> include/linux/soc/mediatek/mtk-cmdq.h | 19 +++++++++++++++++++
> >>> 3 files changed, 39 insertions(+)
> >>>
> >>> diff --git a/drivers/soc/mediatek/mtk-cmdq-helper.c b/drivers/soc/mediatek/mtk-cmdq-helper.c
> >>> index bf32e3b2ca6c..817a5a97dbe5 100644
> >>> --- a/drivers/soc/mediatek/mtk-cmdq-helper.c
> >>> +++ b/drivers/soc/mediatek/mtk-cmdq-helper.c
> >>> @@ -18,6 +18,10 @@ struct cmdq_instruction {
> >>> union {
> >>> u32 value;
> >>> u32 mask;
> >>> + struct {
> >>> + u16 arg_c;
> >>> + u16 src_reg;
> >>> + };
> >>> };
> >>> union {
> >>> u16 offset;
> >>> @@ -222,6 +226,21 @@ int cmdq_pkt_write_mask(struct cmdq_pkt *pkt, u8 subsys,
> >>> }
> >>> EXPORT_SYMBOL(cmdq_pkt_write_mask);
> >>>
> >>> +int cmdq_pkt_write_s(struct cmdq_pkt *pkt, u16 high_addr_reg_idx,
> >>> + u16 addr_low, u16 src_reg_idx)
> >>> +{
> >>
> >> Do I understand correctly that we use CMDQ_ADDR_HIGH(addr) and
> >> CMDQ_ADDR_LOW(addr) to calculate in the client high_addr_reg_idx and addr_low
> >> respectively?
> >>
> >> In that case I think a better interface would be to pass the address and do the
> >> high/low calculation in the cmdq_pkt_write_s
> >
> > Not exactly. The high_addr_reg_idx parameter is index of internal
> > register (which store address bit[47:16]), not result of
> > CMDQ_ADDR_HIGH(addr).
> >
> > The CMDQ_ADDR_HIGH macro use in patch 02/11 cmdq_pkt_assign() api. This
> > api helps assign address bit[47:16] into one of internal register by
> > index. And same index could be use in cmdq_pkt_write_s(). The gce
> > combine bit[47:16] in internal register and bit[15:0] in addr_low
> > parameter to final address. So it is better to keep interface in this
> > way.
> >
>
> Got it, but then why don't we call cmdq_pkt_assign() in cmdq_pkt_write_s()? This
> way we would get a clean API for what we want to do.
> Do we expect other users of cmdq_pkt_assign()? Otherwise we could keep it
> private the this file and don't export it.
Considering this case: write 2 register 0xaabb00c0 0xaabb00d0.
If we call assign inside write_s api it will be:
assign aabb to internal reg 0
write reg 0 + 0x00c0
assign aabb to internal reg 0
write reg 0 + 0x00d0
But if we let client decide timing to call assign, it will be like:
assign aabb to internal reg 0
write reg 0 + 0x00c0
write reg 0 + 0x00d0
The first way uses 4 command and second one uses only 3 command.
Thus it is better to let client call assign explicitly.
>
> By the way, why do you postfix the _s, I understand that it reflects the large
> DMA access but I wonder why you choose '_s'.
>
The name of this command is "write_s" which is hardware spec.
I'm just following it since it is a common language between gce sw/hw
designers.
Regards,
Dennis
> Regards,
> Matthias
>
> >
> > Regards,
> > Dennis
> >
> >>
> >> Regards,
> >> Matthias
> >>
> >>> + struct cmdq_instruction inst = {};
> >>> +
> >>> + inst.op = CMDQ_CODE_WRITE_S;
> >>> + inst.src_t = CMDQ_REG_TYPE;
> >>> + inst.sop = high_addr_reg_idx;
> >>> + inst.offset = addr_low;
> >>> + inst.src_reg = src_reg_idx;
> >>> +
> >>> + return cmdq_pkt_append_command(pkt, inst);
> >>> +}
> >>> +EXPORT_SYMBOL(cmdq_pkt_write_s);
> >>> +
> >>> int cmdq_pkt_wfe(struct cmdq_pkt *pkt, u16 event)
> >>> {
> >>> struct cmdq_instruction inst = { {0} };
> >>> diff --git a/include/linux/mailbox/mtk-cmdq-mailbox.h b/include/linux/mailbox/mtk-cmdq-mailbox.h
> >>> index 121c3bb6d3de..ee67dd3b86f5 100644
> >>> --- a/include/linux/mailbox/mtk-cmdq-mailbox.h
> >>> +++ b/include/linux/mailbox/mtk-cmdq-mailbox.h
> >>> @@ -59,6 +59,7 @@ enum cmdq_code {
> >>> CMDQ_CODE_JUMP = 0x10,
> >>> CMDQ_CODE_WFE = 0x20,
> >>> CMDQ_CODE_EOC = 0x40,
> >>> + CMDQ_CODE_WRITE_S = 0x90,
> >>> CMDQ_CODE_LOGIC = 0xa0,
> >>> };
> >>>
> >>> diff --git a/include/linux/soc/mediatek/mtk-cmdq.h b/include/linux/soc/mediatek/mtk-cmdq.h
> >>> index 83340211e1d3..e1c5a7549b4f 100644
> >>> --- a/include/linux/soc/mediatek/mtk-cmdq.h
> >>> +++ b/include/linux/soc/mediatek/mtk-cmdq.h
> >>> @@ -12,6 +12,8 @@
> >>> #include <linux/timer.h>
> >>>
> >>> #define CMDQ_NO_TIMEOUT 0xffffffffu
> >>> +#define CMDQ_ADDR_HIGH(addr) ((u32)(((addr) >> 16) & GENMASK(31, 0)))
> >>> +#define CMDQ_ADDR_LOW(addr) ((u16)(addr) | BIT(1))
> >>>
> >>> struct cmdq_pkt;
> >>>
> >>> @@ -103,6 +105,23 @@ int cmdq_pkt_write_mask(struct cmdq_pkt *pkt, u8 subsys,
> >>> u16 offset, u32 value, u32 mask);
> >>>
> >>> /**
> >>> + * cmdq_pkt_write_s() - append write_s command to the CMDQ packet
> >>> + * @pkt: the CMDQ packet
> >>> + * @high_addr_reg_idx: internal register ID which contains high address of pa
> >>> + * @addr_low: low address of pa
> >>> + * @src_reg_idx: the CMDQ internal register ID which cache source value
> >>> + *
> >>> + * Return: 0 for success; else the error code is returned
> >>> + *
> >>> + * Support write value to physical address without subsys. Use CMDQ_ADDR_HIGH()
> >>> + * to get high address and call cmdq_pkt_assign() to assign value into internal
> >>> + * reg. Also use CMDQ_ADDR_LOW() to get low address for addr_low parameter when
> >>> + * call to this function.
> >>> + */
> >>> +int cmdq_pkt_write_s(struct cmdq_pkt *pkt, u16 high_addr_reg_idx,
> >>> + u16 addr_low, u16 src_reg_idx);
> >>> +
> >>> +/**
> >>> * cmdq_pkt_wfe() - append wait for event command to the CMDQ packet
> >>> * @pkt: the CMDQ packet
> >>> * @event: the desired event type to "wait and CLEAR"
> >>>
> >
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