linux-kernel - Re: [PATCH v2 16/18] media: rzg2l-cru: Add function pointer to check if FIFO is empty

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Message-ID: <20250223200043.GC15344@pendragon.ideasonboard.com>
Date: Sun, 23 Feb 2025 22:00:43 +0200
From: Laurent Pinchart <laurent.pinchart@...asonboard.com>
To: Tommaso Merciai <tommaso.merciai.xr@...renesas.com>
Cc: tomm.merciai@...il.com, linux-renesas-soc@...r.kernel.org,
	linux-media@...r.kernel.org, biju.das.jz@...renesas.com,
	prabhakar.mahadev-lad.rj@...renesas.com,
	Mauro Carvalho Chehab <mchehab@...nel.org>,
	Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>,
	Geert Uytterhoeven <geert+renesas@...der.be>,
	Magnus Damm <magnus.damm@...il.com>,
	Hans Verkuil <hverkuil@...all.nl>,
	Uwe Kleine-König <u.kleine-koenig@...libre.com>,
	Sakari Ailus <sakari.ailus@...ux.intel.com>,
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 16/18] media: rzg2l-cru: Add function pointer to check
 if FIFO is empty

Hi Tommaso,

Thank you for the patch.

On Fri, Feb 21, 2025 at 04:55:30PM +0100, Tommaso Merciai wrote:
> From: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
> 
> Add a `fifo_empty` function pointer to the `rzg2l_cru_info` structure and
> pass it as part of the OF data. On RZ/G3E and RZ/V2H(P) SoCs, checking if
> the FIFO is empty requires a different register configuration.
> 
> Implement `rzg2l_fifo_empty()` and update the code to use it from the
> function pointer.
> 
> Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
> Signed-off-by: Tommaso Merciai <tommaso.merciai.xr@...renesas.com>
> ---
>  .../platform/renesas/rzg2l-cru/rzg2l-core.c   |  1 +
>  .../platform/renesas/rzg2l-cru/rzg2l-cru.h    |  3 +++
>  .../platform/renesas/rzg2l-cru/rzg2l-video.c  | 23 +++++++++++++------
>  3 files changed, 20 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/media/platform/renesas/rzg2l-cru/rzg2l-core.c b/drivers/media/platform/renesas/rzg2l-cru/rzg2l-core.c
> index 302f792cb415..e4fb3e12d6bf 100644
> --- a/drivers/media/platform/renesas/rzg2l-cru/rzg2l-core.c
> +++ b/drivers/media/platform/renesas/rzg2l-cru/rzg2l-core.c
> @@ -362,6 +362,7 @@ static const struct rzg2l_cru_info rzgl2_cru_info = {
>  	.irq_handler = rzg2l_cru_irq,
>  	.enable_interrupts = rzg2l_cru_enable_interrupts,
>  	.disable_interrupts = rzg2l_cru_disable_interrupts,
> +	.fifo_empty = rzg2l_fifo_empty,
>  };
>  
>  static const struct of_device_id rzg2l_cru_of_id_table[] = {
> diff --git a/drivers/media/platform/renesas/rzg2l-cru/rzg2l-cru.h b/drivers/media/platform/renesas/rzg2l-cru/rzg2l-cru.h
> index 3f694044d8cd..2e17bfef43ce 100644
> --- a/drivers/media/platform/renesas/rzg2l-cru/rzg2l-cru.h
> +++ b/drivers/media/platform/renesas/rzg2l-cru/rzg2l-cru.h
> @@ -88,6 +88,7 @@ struct rzg2l_cru_info {
>  	irqreturn_t (*irq_handler)(int irq, void *data);
>  	void (*enable_interrupts)(struct rzg2l_cru_dev *cru);
>  	void (*disable_interrupts)(struct rzg2l_cru_dev *cru);
> +	bool (*fifo_empty)(struct rzg2l_cru_dev *cru);
>  };
>  
>  /**
> @@ -185,4 +186,6 @@ const struct rzg2l_cru_ip_format *rzg2l_cru_ip_index_to_fmt(u32 index);
>  void rzg2l_cru_enable_interrupts(struct rzg2l_cru_dev *cru);
>  void rzg2l_cru_disable_interrupts(struct rzg2l_cru_dev *cru);
>  
> +bool rzg2l_fifo_empty(struct rzg2l_cru_dev *cru);
> +
>  #endif
> diff --git a/drivers/media/platform/renesas/rzg2l-cru/rzg2l-video.c b/drivers/media/platform/renesas/rzg2l-cru/rzg2l-video.c
> index 5ffa3173af62..7cc83486ce03 100644
> --- a/drivers/media/platform/renesas/rzg2l-cru/rzg2l-video.c
> +++ b/drivers/media/platform/renesas/rzg2l-cru/rzg2l-video.c
> @@ -244,9 +244,23 @@ static int rzg2l_cru_initialize_image_conv(struct rzg2l_cru_dev *cru,
>  	return 0;
>  }
>  
> -void rzg2l_cru_stop_image_processing(struct rzg2l_cru_dev *cru)
> +bool rzg2l_fifo_empty(struct rzg2l_cru_dev *cru)
>  {
>  	u32 amnfifopntr, amnfifopntr_w, amnfifopntr_r_y;
> +
> +	amnfifopntr = rzg2l_cru_read(cru, AMnFIFOPNTR);
> +
> +	amnfifopntr_w = amnfifopntr & AMnFIFOPNTR_FIFOWPNTR;
> +	amnfifopntr_r_y =
> +		(amnfifopntr & AMnFIFOPNTR_FIFORPNTR_Y) >> 16;
> +	if (amnfifopntr_w == amnfifopntr_r_y)
> +		return true;
> +
> +	return false;

Maybe

	return amnfifopntr_w == amnfifopntr_r_y;

> +}

I wonder if this function, along with rzg2l_cru_enable_interrupts() and
rzg2l_cru_disable_interrupts(), should be moved to rzg2l-core.c. Either
way,

Reviewed-by: Laurent Pinchart <laurent.pinchart+renesas@...asonboard.com>

> +
> +void rzg2l_cru_stop_image_processing(struct rzg2l_cru_dev *cru)
> +{
>  	unsigned int retries = 0;
>  	unsigned long flags;
>  	u32 icnms;
> @@ -274,12 +288,7 @@ void rzg2l_cru_stop_image_processing(struct rzg2l_cru_dev *cru)
>  
>  	/* Wait until the FIFO becomes empty */
>  	for (retries = 5; retries > 0; retries--) {
> -		amnfifopntr = rzg2l_cru_read(cru, AMnFIFOPNTR);
> -
> -		amnfifopntr_w = amnfifopntr & AMnFIFOPNTR_FIFOWPNTR;
> -		amnfifopntr_r_y =
> -			(amnfifopntr & AMnFIFOPNTR_FIFORPNTR_Y) >> 16;
> -		if (amnfifopntr_w == amnfifopntr_r_y)
> +		if (cru->info->fifo_empty(cru))
>  			break;
>  
>  		usleep_range(10, 20);

-- 
Regards,

Laurent Pinchart