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    SubjectRe: [PATCH v1 03/11] soc: mediatek: cmdq: add write_s function
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    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@mediatek.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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