Re: [PATCH 08/15] soc: mediatek: Add cmdq_pkt_finalize_loop to CMDQ driver

["CK Hu (胡俊光)" <ck.hu@mediatek.com>]

Hi, Jason:

On Tue, 2023-09-19 at 03:21 +0800, Jason-JH.Lin wrote:
> Add cmdq_pkt_finalize_loop to CMDQ driver.
> 
> cmdq_pkt_finalize_loop appends end of command(EOC) instruction and
> jump to start of command buffer instruction to make the command
> buffer loopable.
> 
> Signed-off-by: Jason-JH.Lin <jason-jh.lin@mediatek.com>
> ---
>  drivers/soc/mediatek/mtk-cmdq-helper.c | 23 +++++++++++++++++++++++
>  include/linux/soc/mediatek/mtk-cmdq.h  |  8 ++++++++
>  2 files changed, 31 insertions(+)
> 
> diff --git a/drivers/soc/mediatek/mtk-cmdq-helper.c
> b/drivers/soc/mediatek/mtk-cmdq-helper.c
> index 4be2a18a4a02..bbb127620bb3 100644
> --- a/drivers/soc/mediatek/mtk-cmdq-helper.c
> +++ b/drivers/soc/mediatek/mtk-cmdq-helper.c
> @@ -475,6 +475,29 @@ int cmdq_pkt_finalize(struct cmdq_pkt *pkt)
>  }
>  EXPORT_SYMBOL(cmdq_pkt_finalize);
>  
> +int cmdq_pkt_finalize_loop(struct cmdq_pkt *pkt)
> +{
> +	struct cmdq_instruction inst = { {0} };
> +	int err;
> +
> +	/* insert EOC and generate IRQ for each command iteration */
> +	inst.op = CMDQ_CODE_EOC;
> +	inst.value = CMDQ_EOC_IRQ_EN;
> +	err = cmdq_pkt_append_command(pkt, inst);
> +	if (err < 0)
> +		return err;
> +
> +	/* JUMP to start of pkt */
> +	err = cmdq_pkt_jump(pkt, pkt->pa_base);
> +	if (err < 0)
> +		return err;

Could you explain the case that a loop thread would trigger an
interrupt? In DRM crc function, the loop thread need not to trigger
interrupt, so I'm curious about this.

Regards,
CK

> +
> +	pkt->loop = true;
> +
> +	return err;
> +}
> +EXPORT_SYMBOL(cmdq_pkt_finalize_loop);
> +
>  int cmdq_pkt_flush_async(struct cmdq_pkt *pkt)
>  {
>  	int err;
> diff --git a/include/linux/soc/mediatek/mtk-cmdq.h
> b/include/linux/soc/mediatek/mtk-cmdq.h
> index 837ad8656adc..38a8e47da338 100644
> --- a/include/linux/soc/mediatek/mtk-cmdq.h
> +++ b/include/linux/soc/mediatek/mtk-cmdq.h
> @@ -323,6 +323,14 @@ int cmdq_pkt_jump(struct cmdq_pkt *pkt,
> dma_addr_t addr);
>   */
>  int cmdq_pkt_finalize(struct cmdq_pkt *pkt);
>  
> +/**
> + * cmdq_pkt_finalize_loop() - Append EOC and jump to start command.
> + * @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