Re: [PATCH 1/9] soc: mediatek: cmdq: Remove unused helper funciton

[CK Hu (胡俊光)]

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:
> > cmdq_pkt_create(), cmdq_pkt_destroy(), and cmdq_pkt_flush_async()
> > are not used by all client drivers (MediaTek drm driver and
> > MediaTek mdp3 driver),
> > 
> 
> Hello CK,
> 
> We can technically force the hand to say that this is true - but only
> because
> these two functions are copy-pasted in both mediatek-drm and MDP3
> drivers with
> no meaningful changes, as in, the only change is that `pkt` is
> supposed to be
> preallocated in both of the variants, while the one in mtk-cmdq-
> helper allocates
> it on its own.
> 
> Code duplication is something that we want to avoid, not something
> that we want
> to embrace: removing those functions from cmdq-helper with the plan
> to keep
> duplicating them in each MediaTek driver that uses CMDQ packets is
> plain wrong.
> 
> This - especially because I'm sure that we will see yet another copy-
> paste of
> those two functions in a future ISP driver, bringing the duplication
> count to
> 3 (or actually, 3 by 2 functions = 6 times).
> 
> On the other hand, removing the cmdq_pkt_flush_async() function is
> something
> that I *do* support, as it's only doing two simple calls that are not
> even
> specific to cmdq, but more like "generic stuff".
> 
> In short, as it is right now, this is a NACK - but if you change this
> commit to
> remove only cmdq_pkt_flush_async() I would agree.
> 
> The right thing to do is to remove the duplicated functions:
>   - mtk_drm_cmdq_pkt_create()
>   - mtk_drm_cmdq_pkt_destroy()
>   - mdp_cmdq_pkt_create()
>   - mdp_cmdq_pkt_destroy()
> 
> ...and migrate both drivers to use the common cmdq helper code
> instea, but that's
> something that can come later.
> 
> For now, you can simply perform the ->cl removal on all duplicated
> functions, then
> we can migrate them all to the common helper, removing duplication
> all along.

OK, I would refine cmdq_pkt_create()/cmdq_pkt_destroy() and let client
driver use these common functions.

Regards,
CK

> 
> Regards,
> Angelo
> 
> > Signed-off-by: Chun-Kuang Hu <chunkuang.hu@xxxxxxxxxx>
> > ---
> >   drivers/soc/mediatek/mtk-cmdq-helper.c | 59 -------------------
> > -------
> >   include/linux/soc/mediatek/mtk-cmdq.h  | 40 -----------------
> >   2 files changed, 99 deletions(-)
> > 
> > diff --git a/drivers/soc/mediatek/mtk-cmdq-helper.c
> > b/drivers/soc/mediatek/mtk-cmdq-helper.c
> > index b0cd071c4719..67e17974d1e6 100644
> > --- a/drivers/soc/mediatek/mtk-cmdq-helper.c
> > +++ b/drivers/soc/mediatek/mtk-cmdq-helper.c
> > @@ -105,50 +105,6 @@ void cmdq_mbox_destroy(struct cmdq_client
> > *client)
> >   }
> >   EXPORT_SYMBOL(cmdq_mbox_destroy);
> >   
> > -struct cmdq_pkt *cmdq_pkt_create(struct cmdq_client *client,
> > size_t size)
> > -{
> > -	struct cmdq_pkt *pkt;
> > -	struct device *dev;
> > -	dma_addr_t dma_addr;
> > -
> > -	pkt = kzalloc(sizeof(*pkt), GFP_KERNEL);
> > -	if (!pkt)
> > -		return ERR_PTR(-ENOMEM);
> > -	pkt->va_base = kzalloc(size, GFP_KERNEL);
> > -	if (!pkt->va_base) {
> > -		kfree(pkt);
> > -		return ERR_PTR(-ENOMEM);
> > -	}
> > -	pkt->buf_size = size;
> > -	pkt->cl = (void *)client;
> > -
> > -	dev = client->chan->mbox->dev;
> > -	dma_addr = dma_map_single(dev, pkt->va_base, pkt->buf_size,
> > -				  DMA_TO_DEVICE);
> > -	if (dma_mapping_error(dev, dma_addr)) {
> > -		dev_err(dev, "dma map failed, size=%u\n",
> > (u32)(u64)size);
> > -		kfree(pkt->va_base);
> > -		kfree(pkt);
> > -		return ERR_PTR(-ENOMEM);
> > -	}
> > -
> > -	pkt->pa_base = dma_addr;
> > -
> > -	return pkt;
> > -}
> > -EXPORT_SYMBOL(cmdq_pkt_create);
> > -
> > -void cmdq_pkt_destroy(struct cmdq_pkt *pkt)
> > -{
> > -	struct cmdq_client *client = (struct cmdq_client *)pkt->cl;
> > -
> > -	dma_unmap_single(client->chan->mbox->dev, pkt->pa_base, pkt-
> > >buf_size,
> > -			 DMA_TO_DEVICE);
> > -	kfree(pkt->va_base);
> > -	kfree(pkt);
> > -}
> > -EXPORT_SYMBOL(cmdq_pkt_destroy);
> > -
> >   static int cmdq_pkt_append_command(struct cmdq_pkt *pkt,
> >   				   struct cmdq_instruction inst)
> >   {
> > @@ -426,19 +382,4 @@ int cmdq_pkt_finalize(struct cmdq_pkt *pkt)
> >   }
> >   EXPORT_SYMBOL(cmdq_pkt_finalize);
> >   
> > -int cmdq_pkt_flush_async(struct cmdq_pkt *pkt)
> > -{
> > -	int err;
> > -	struct cmdq_client *client = (struct cmdq_client *)pkt->cl;
> > -
> > -	err = mbox_send_message(client->chan, pkt);
> > -	if (err < 0)
> > -		return err;
> > -	/* We can send next packet immediately, so just call txdone. */
> > -	mbox_client_txdone(client->chan, 0);
> > -
> > -	return 0;
> > -}
> > -EXPORT_SYMBOL(cmdq_pkt_flush_async);
> > -
> >   MODULE_LICENSE("GPL v2");
> > diff --git a/include/linux/soc/mediatek/mtk-cmdq.h
> > b/include/linux/soc/mediatek/mtk-cmdq.h
> > index 649955d2cf5c..6c42d817d368 100644
> > --- a/include/linux/soc/mediatek/mtk-cmdq.h
> > +++ b/include/linux/soc/mediatek/mtk-cmdq.h
> > @@ -59,21 +59,6 @@ struct cmdq_client *cmdq_mbox_create(struct
> > device *dev, int index);
> >    */
> >   void cmdq_mbox_destroy(struct cmdq_client *client);
> >   
> > -/**
> > - * cmdq_pkt_create() - create a CMDQ packet
> > - * @client:	the CMDQ mailbox client
> > - * @size:	required CMDQ buffer size
> > - *
> > - * Return: CMDQ packet pointer
> > - */
> > -struct cmdq_pkt *cmdq_pkt_create(struct cmdq_client *client,
> > size_t size);
> > -
> > -/**
> > - * cmdq_pkt_destroy() - destroy the CMDQ packet
> > - * @pkt:	the CMDQ packet
> > - */
> > -void cmdq_pkt_destroy(struct cmdq_pkt *pkt);
> > -
> >   /**
> >    * cmdq_pkt_write() - append write command to the CMDQ packet
> >    * @pkt:	the CMDQ packet
> > @@ -266,19 +251,6 @@ int cmdq_pkt_jump(struct cmdq_pkt *pkt,
> > dma_addr_t addr);
> >    */
> >   int cmdq_pkt_finalize(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
> > - * @pkt:	the CMDQ packet
> > - *
> > - * Return: 0 for success; else the error code is returned
> > - *
> > - * Trigger CMDQ to asynchronously execute the CMDQ packet and call
> > back
> > - * at the end of done packet. Note that this is an ASYNC function.
> > When the
> > - * function returned, it may or may not be finished.
> > - */
> > -int cmdq_pkt_flush_async(struct cmdq_pkt *pkt);
> > -
> >   #else /* IS_ENABLED(CONFIG_MTK_CMDQ) */
> >   
> >   static inline int cmdq_dev_get_client_reg(struct device *dev,
> > @@ -294,13 +266,6 @@ static inline struct cmdq_client
> > *cmdq_mbox_create(struct device *dev, int index
> >   
> >   static inline void cmdq_mbox_destroy(struct cmdq_client *client)
> > { }
> >   
> > -static inline  struct cmdq_pkt *cmdq_pkt_create(struct cmdq_client
> > *client, size_t size)
> > -{
> > -	return ERR_PTR(-EINVAL);
> > -}
> > -
> > -static inline void cmdq_pkt_destroy(struct cmdq_pkt *pkt) { }
> > -
> >   static inline int cmdq_pkt_write(struct cmdq_pkt *pkt, u8 subsys,
> > u16 offset, u32 value)
> >   {
> >   	return -ENOENT;
> > @@ -384,11 +349,6 @@ static inline int cmdq_pkt_finalize(struct
> > cmdq_pkt *pkt)
> >   	return -EINVAL;
> >   }
> >   
> > -static inline int cmdq_pkt_flush_async(struct cmdq_pkt *pkt)
> > -{
> > -	return -EINVAL;
> > -}
> > -
> >   #endif /* IS_ENABLED(CONFIG_MTK_CMDQ) */
> >   
> >   #endif	/* __MTK_CMDQ_H__ */
> 
>