linux-kernel - Re: [PATCH v5 09/13] soc: mediatek: cmdq: add write

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Date:   Mon, 25 May 2020 10:27:01 +0800
From:   Dennis-YC Hsieh <dennis-yc.hsieh@...iatek.com>
To:     Matthias Brugger <matthias.bgg@...il.com>
CC:     Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Jassi Brar <jassisinghbrar@...il.com>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        <linux-kernel@...r.kernel.org>,
        <linux-mediatek@...ts.infradead.org>, <devicetree@...r.kernel.org>,
        <wsd_upstream@...iatek.com>, <dri-devel@...ts.freedesktop.org>,
        Bibby Hsieh <bibby.hsieh@...iatek.com>,
        CK Hu <ck.hu@...iatek.com>,
        Houlong Wei <houlong.wei@...iatek.com>,
        <linux-arm-kernel@...ts.infradead.org>,
        HS Liao <hs.liao@...iatek.com>
Subject: Re: [PATCH v5 09/13] soc: mediatek: cmdq: add write_s value function


On Sun, 2020-05-24 at 20:13 +0200, Matthias Brugger wrote:
> 
> On 24/05/2020 19:31, Dennis-YC Hsieh wrote:
> > Hi Matthias,
> > 
> > Thanks for your comment.
> > 
> > On Sat, 2020-05-16 at 20:20 +0200, Matthias Brugger wrote:
> >>
> >> On 08/03/2020 11:52, Dennis YC Hsieh wrote:
> >>> add write_s function in cmdq helper functions which
> >>> writes a constant value to address with large dma
> >>> access support.
> >>>
> >>> Signed-off-by: Dennis YC Hsieh <dennis-yc.hsieh@...iatek.com>
> >>> Reviewed-by: CK Hu <ck.hu@...iatek.com>
> >>> ---
> >>>  drivers/soc/mediatek/mtk-cmdq-helper.c | 26 ++++++++++++++++++++++++++
> >>>  include/linux/soc/mediatek/mtk-cmdq.h  | 14 ++++++++++++++
> >>>  2 files changed, 40 insertions(+)
> >>>
> >>> diff --git a/drivers/soc/mediatek/mtk-cmdq-helper.c b/drivers/soc/mediatek/mtk-cmdq-helper.c
> >>> index 03c129230cd7..a9ebbabb7439 100644
> >>> --- a/drivers/soc/mediatek/mtk-cmdq-helper.c
> >>> +++ b/drivers/soc/mediatek/mtk-cmdq-helper.c
> >>> @@ -269,6 +269,32 @@ int cmdq_pkt_write_s(struct cmdq_pkt *pkt, u16 high_addr_reg_idx,
> >>>  }
> >>>  EXPORT_SYMBOL(cmdq_pkt_write_s);
> >>>  
> >>> +int cmdq_pkt_write_s_value(struct cmdq_pkt *pkt, u16 high_addr_reg_idx,
> >>> +			   u16 addr_low, u32 value, u32 mask)
> >>> +{
> >>> +	struct cmdq_instruction inst = { {0} };
> >>> +	int err;
> >>> +
> >>> +	if (mask != U32_MAX) {
> >>> +		inst.op = CMDQ_CODE_MASK;
> >>> +		inst.mask = ~mask;
> >>> +		err = cmdq_pkt_append_command(pkt, inst);
> >>> +		if (err < 0)
> >>> +			return err;
> >>> +
> >>> +		inst.op = CMDQ_CODE_WRITE_S_MASK;
> >>> +	} else {
> >>> +		inst.op = CMDQ_CODE_WRITE_S;
> >>> +	}
> >>> +
> >>> +	inst.sop = high_addr_reg_idx;
> >>
> >> Writing u16 value in a 5 bit wide variable?
> > 
> > We need only 5 bits in this case. I'll change high_addr_reg_idx
> > parameter to u8.
> > 
> 
> Ok, please make sure to mask the value, so that it's explicit in the code that
> we only use the lowest 5 bits of high_addr_reg_idx.

Is it necessary to mask the value?
Since sop already defined as "u8 sop:5;", I thought it is explicit that
only use 5 bits and compiler should do the rest jobs.


Regards,
Dennis

> 
> Regards,
> Matthias
> 
> >>
> >>> +	inst.offset = addr_low;
> >>> +	inst.value = value;
> >>> +
> >>> +	return cmdq_pkt_append_command(pkt, inst);
> >>> +}
> >>> +EXPORT_SYMBOL(cmdq_pkt_write_s_value);
> >>> +
> >>>  int cmdq_pkt_wfe(struct cmdq_pkt *pkt, u16 event)
> >>>  {
> >>>  	struct cmdq_instruction inst = { {0} };
> >>> diff --git a/include/linux/soc/mediatek/mtk-cmdq.h b/include/linux/soc/mediatek/mtk-cmdq.h
> >>> index 01b4184af310..fec292aac83c 100644
> >>> --- a/include/linux/soc/mediatek/mtk-cmdq.h
> >>> +++ b/include/linux/soc/mediatek/mtk-cmdq.h
> >>> @@ -135,6 +135,20 @@ int cmdq_pkt_read_s(struct cmdq_pkt *pkt, u16 high_addr_reg_idx, u16 addr_low,
> >>>  int cmdq_pkt_write_s(struct cmdq_pkt *pkt, u16 high_addr_reg_idx,
> >>>  		     u16 addr_low, u16 src_reg_idx, u32 mask);
> >>>  
> >>> +/**
> >>> + * cmdq_pkt_write_s_value() - append write_s command with mask to the CMDQ
> >>> + *			      packet which write value to a physical address
> >>> + * @pkt:	the CMDQ packet
> >>> + * @high_addr_reg_idx:	internal regisger ID which contains high address of pa
> >>
> >> register
> > 
> > will fix
> > 
> > 
> > Regards,
> > Dennis
> > 
> >>
> >>> + * @addr_low:	low address of pa
> >>> + * @value:	the specified target value
> >>> + * @mask:	the specified target mask
> >>> + *
> >>> + * Return: 0 for success; else the error code is returned
> >>> + */
> >>> +int cmdq_pkt_write_s_value(struct cmdq_pkt *pkt, u16 high_addr_reg_idx,
> >>> +			   u16 addr_low, u32 value, u32 mask);
> >>> +
> >>>  /**
> >>>   * cmdq_pkt_wfe() - append wait for event command to the CMDQ packet
> >>>   * @pkt:	the CMDQ packet
> >>>
> >