linux-kernel - Re: [PATCH 06/18] dmaengine: bcm2835: make address increment platform independent

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Date: Wed, 5 Jun 2024 13:52:44 -0400
From: Frank Li <Frank.li@....com>
To: Dave Stevenson <dave.stevenson@...pberrypi.com>
Cc: Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>,
	Florian Fainelli <florian.fainelli@...adcom.com>,
	Broadcom internal kernel review list <bcm-kernel-feedback-list@...adcom.com>,
	Ray Jui <rjui@...adcom.com>, Scott Branden <sbranden@...adcom.com>,
	Vinod Koul <vkoul@...nel.org>, Maxime Ripard <mripard@...nel.org>,
	Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
	Thomas Zimmermann <tzimmermann@...e.de>,
	David Airlie <airlied@...il.com>, Daniel Vetter <daniel@...ll.ch>,
	Ulf Hansson <ulf.hansson@...aro.org>,
	Mark Brown <broonie@...nel.org>, Christoph Hellwig <hch@....de>,
	Marek Szyprowski <m.szyprowski@...sung.com>,
	Robin Murphy <robin.murphy@....com>,
	Liam Girdwood <lgirdwood@...il.com>,
	Jaroslav Kysela <perex@...ex.cz>, Takashi Iwai <tiwai@...e.com>,
	Vladimir Murzin <vladimir.murzin@....com>,
	Phil Elwell <phil@...pberrypi.com>,
	Stefan Wahren <wahrenst@....net>,
	Serge Semin <Sergey.Semin@...kalelectronics.ru>,
	devicetree@...r.kernel.org, linux-rpi-kernel@...ts.infradead.org,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	dmaengine@...r.kernel.org, dri-devel@...ts.freedesktop.org,
	linux-mmc@...r.kernel.org, linux-spi@...r.kernel.org,
	iommu@...ts.linux.dev, linux-sound@...r.kernel.org,
	Stefan Wahren <stefan.wahren@...e.com>
Subject: Re: [PATCH 06/18] dmaengine: bcm2835: make address increment
 platform independent

On Fri, May 24, 2024 at 07:26:50PM +0100, Dave Stevenson wrote:
> From: Stefan Wahren <stefan.wahren@...e.com>
> 
> Actually the criteria to increment source & destination address doesn't
> based on platform specific bits. It's just the DMA transfer direction which
> is translated into the info bits. So introduce two new helper functions
> and get the rid of these platform specifics.
> 

Fix increment source & destination address depend on the platform drvdata.
It should be depend on dma_transfer_direction.

look like it is bug fixes. Can you add fixes tag.

> Signed-off-by: Stefan Wahren <wahrenst@....net>
> Signed-off-by: Dave Stevenson <dave.stevenson@...pberrypi.com>
> ---
>  drivers/dma/bcm2835-dma.c | 28 ++++++++++++++++++++++------
>  1 file changed, 22 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/dma/bcm2835-dma.c b/drivers/dma/bcm2835-dma.c
> index ef452ebb3c15..d6c5a2762a46 100644
> --- a/drivers/dma/bcm2835-dma.c
> +++ b/drivers/dma/bcm2835-dma.c
> @@ -252,6 +252,24 @@ static u32 bcm2835_dma_prepare_cb_extra(struct bcm2835_chan *c,
>  	return result;
>  }
>  
> +static inline bool need_src_incr(enum dma_transfer_direction direction)
> +{
> +	return direction != DMA_DEV_TO_MEM;
> +}
> +
> +static inline bool need_dst_incr(enum dma_transfer_direction direction)
> +{
> +	switch (direction) {
> +	case DMA_MEM_TO_MEM:
> +	case DMA_DEV_TO_MEM:
> +		return true;
> +	default:
> +		break;
> +	}
> +
> +	return false;
> +}
> +
>  static void bcm2835_dma_free_cb_chain(struct bcm2835_desc *desc)
>  {
>  	size_t i;
> @@ -336,10 +354,8 @@ static inline size_t bcm2835_dma_count_frames_for_sg(
>   * @cyclic:         it is a cyclic transfer
>   * @info:           the default info bits to apply per controlblock
>   * @frames:         number of controlblocks to allocate
> - * @src:            the src address to assign (if the S_INC bit is set
> - *                  in @info, then it gets incremented)
> - * @dst:            the dst address to assign (if the D_INC bit is set
> - *                  in @info, then it gets incremented)
> + * @src:            the src address to assign
> + * @dst:            the dst address to assign
>   * @buf_len:        the full buffer length (may also be 0)
>   * @period_len:     the period length when to apply @finalextrainfo
>   *                  in addition to the last transfer
> @@ -408,9 +424,9 @@ static struct bcm2835_desc *bcm2835_dma_create_cb_chain(
>  			d->cb_list[frame - 1].cb->next = cb_entry->paddr;
>  
>  		/* update src and dst and length */
> -		if (src && (info & BCM2835_DMA_S_INC))
> +		if (src && need_src_incr(direction))
>  			src += control_block->length;
> -		if (dst && (info & BCM2835_DMA_D_INC))
> +		if (dst && need_dst_incr(direction))
>  			dst += control_block->length;
>  
>  		/* Length of total transfer */
> -- 
> 2.34.1
>