Re: [PATCH 2/9] soc: mediatek: cmdq: Add parameter shift_pa to cmdq_pkt_jump()

["CK Hu (胡俊光)" <ck.hu@mediatek.com>]

Hi, Angelo:

On Thu, 2024-02-15 at 11:40 +0100, AngeloGioacchino Del Regno wrote:
> Il 15/02/24 01:49, Chun-Kuang Hu ha scritto:
> > In original design, cmdq_pkt_jump() call cmdq_get_shift_pa() every
> > time to get shift_pa. But the shift_pa is constant value for each
> > SoC, so client driver just need to call cmdq_get_shift_pa() once
> > and pass shift_pa to cmdq_pkt_jump() to prevent frequent function
> > call.
> > 
> 
> As far as I understand, the CMDQ supports both relative and absolute
> jumps, right?
> 
> Here's my proposal:
>   - Add a new function cmdq_pkt_jump_rel() or
> cmdq_pkt_jump_relative()
>     * note: I prefer "rel", as maybe in a future we'll get a jump_abs
> function? :-)
>   - Don't touch the cmdq_pkt_jump() function for one cycle
>     - Migrate mediatek-drm to use cmdq_pkt_jump_rel()
>   - Remove cmdq_pkt_jump() in the next cycle.
> 
> What do you think?

Good idea. I would create cmdq_pkt_jump_abs() to replace
cmdq_pkt_jump() and fix the wrong definition of CMDQ_JUMP_RELATIVE as:

#define CMDQ_JUMP_RELATIVE 0
#define CMDQ_JUMP_ABSOLUTE 1

Regards,
CK

> 
> Regards,
> Angelo
> 
> > Signed-off-by: Chun-Kuang Hu <chunkuang.hu@kernel.org>
> > ---
> >   drivers/soc/mediatek/mtk-cmdq-helper.c | 5 ++---
> >   include/linux/soc/mediatek/mtk-cmdq.h  | 6 ++++--
> >   2 files changed, 6 insertions(+), 5 deletions(-)
> > 
> > diff --git a/drivers/soc/mediatek/mtk-cmdq-helper.c
> > b/drivers/soc/mediatek/mtk-cmdq-helper.c
> > index 67e17974d1e6..ed4ef95adf5b 100644
> > --- a/drivers/soc/mediatek/mtk-cmdq-helper.c
> > +++ b/drivers/soc/mediatek/mtk-cmdq-helper.c
> > @@ -348,14 +348,13 @@ int cmdq_pkt_assign(struct cmdq_pkt *pkt, u16
> > reg_idx, u32 value)
> >   }
> >   EXPORT_SYMBOL(cmdq_pkt_assign);
> >   
> > -int cmdq_pkt_jump(struct cmdq_pkt *pkt, dma_addr_t addr)
> > +int cmdq_pkt_jump(struct cmdq_pkt *pkt, dma_addr_t addr, u8
> > shift_pa)
> >   {
> >   	struct cmdq_instruction inst = {};
> >   
> >   	inst.op = CMDQ_CODE_JUMP;
> >   	inst.offset = CMDQ_JUMP_RELATIVE;
> > -	inst.value = addr >>
> > -		cmdq_get_shift_pa(((struct cmdq_client *)pkt->cl)-
> > >chan);
> > +	inst.value = addr >> shift_pa;
> >   	return cmdq_pkt_append_command(pkt, inst);
> >   }
> >   EXPORT_SYMBOL(cmdq_pkt_jump);
> > diff --git a/include/linux/soc/mediatek/mtk-cmdq.h
> > b/include/linux/soc/mediatek/mtk-cmdq.h
> > index 6c42d817d368..6215191a328d 100644
> > --- a/include/linux/soc/mediatek/mtk-cmdq.h
> > +++ b/include/linux/soc/mediatek/mtk-cmdq.h
> > @@ -238,10 +238,12 @@ int cmdq_pkt_assign(struct cmdq_pkt *pkt, u16
> > reg_idx, u32 value);
> >    *		     a physical address which should contains
> > more instruction.
> >    * @pkt:        the CMDQ packet
> >    * @addr:       physical address of target instruction buffer
> > + * @shift_pa:	shift bits of physical address in CMDQ
> > instruction. This value
> > + *		is got by cmdq_get_shift_pa().
> >    *
> >    * Return: 0 for success; else the error code is returned
> >    */
> > -int cmdq_pkt_jump(struct cmdq_pkt *pkt, dma_addr_t addr);
> > +int cmdq_pkt_jump(struct cmdq_pkt *pkt, dma_addr_t addr, u8
> > shift_pa);
> >   
> >   /**
> >    * cmdq_pkt_finalize() - Append EOC and jump command to pkt.
> > @@ -339,7 +341,7 @@ static inline int cmdq_pkt_assign(struct
> > cmdq_pkt *pkt, u16 reg_idx, u32 value)
> >   	return -EINVAL;
> >   }
> >   
> > -static inline int cmdq_pkt_jump(struct cmdq_pkt *pkt, dma_addr_t
> > addr)
> > +static inline int cmdq_pkt_jump(struct cmdq_pkt *pkt, dma_addr_t
> > addr, u8 shift_pa)
> >   {
> >   	return -EINVAL;
> >   }
> 
> 
> 
>