linux-kernel - Re: [PATCH v2 2/4] dmaengine: rcar-dmac: Add for_each_rcar_dmac

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Date:   Tue, 26 Jan 2021 23:54:40 +0200
From:   Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:     Geert Uytterhoeven <geert+renesas@...der.be>
Cc:     Vinod Koul <vkoul@...nel.org>, Rob Herring <robh+dt@...nel.org>,
        Dan Williams <dan.j.williams@...el.com>,
        Yoshihiro Shimoda <yoshihiro.shimoda.uh@...esas.com>,
        Wolfram Sang <wsa+renesas@...g-engineering.com>,
        dmaengine@...r.kernel.org, devicetree@...r.kernel.org,
        linux-renesas-soc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 2/4] dmaengine: rcar-dmac: Add
 for_each_rcar_dmac_chan() helper

Hi Geert,

Thank you for the patch.

On Mon, Jan 25, 2021 at 03:24:29PM +0100, Geert Uytterhoeven wrote:
> Add and helper macro for iterating over all DMAC channels, taking into

s/and helper/a helper/

> account the channel mask.  Use it where appropriate, to simplify code.
> 
> Restore "reverse Christmas tree" order of local variables while adding a
> new variable.
> 
> Signed-off-by: Geert Uytterhoeven <geert+renesas@...der.be>
> ---
> v2:
>   - Put the full loop control of for_each_rcar_dmac_chan() on a single
>     line, to improve readability.
> ---
>  drivers/dma/sh/rcar-dmac.c | 22 ++++++++++------------
>  1 file changed, 10 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/dma/sh/rcar-dmac.c b/drivers/dma/sh/rcar-dmac.c
> index a57705356e8bb796..537550b4121bbc22 100644
> --- a/drivers/dma/sh/rcar-dmac.c
> +++ b/drivers/dma/sh/rcar-dmac.c
> @@ -209,6 +209,10 @@ struct rcar_dmac {
>  
>  #define to_rcar_dmac(d)		container_of(d, struct rcar_dmac, engine)
>  
> +#define for_each_rcar_dmac_chan(i, chan, dmac)						\

I would have placed the iterator (chan) after the container being
iterated (dmac), but it seems there are some for_each_* macros doing it
the other way around (they may be older though).

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

> +	for (i = 0, chan = &(dmac)->channels[0]; i < (dmac)->n_channels; i++, chan++)	\
> +		if (!((dmac)->channels_mask & BIT(i))) continue; else
> +
>  /*
>   * struct rcar_dmac_of_data - This driver's OF data
>   * @chan_offset_base: DMAC channels base offset
> @@ -817,15 +821,11 @@ static void rcar_dmac_chan_reinit(struct rcar_dmac_chan *chan)
>  
>  static void rcar_dmac_stop_all_chan(struct rcar_dmac *dmac)
>  {
> +	struct rcar_dmac_chan *chan;
>  	unsigned int i;
>  
>  	/* Stop all channels. */
> -	for (i = 0; i < dmac->n_channels; ++i) {
> -		struct rcar_dmac_chan *chan = &dmac->channels[i];
> -
> -		if (!(dmac->channels_mask & BIT(i)))
> -			continue;
> -
> +	for_each_rcar_dmac_chan(i, chan, dmac) {
>  		/* Stop and reinitialize the channel. */
>  		spin_lock_irq(&chan->lock);
>  		rcar_dmac_chan_halt(chan);
> @@ -1828,9 +1828,10 @@ static int rcar_dmac_probe(struct platform_device *pdev)
>  		DMA_SLAVE_BUSWIDTH_2_BYTES | DMA_SLAVE_BUSWIDTH_4_BYTES |
>  		DMA_SLAVE_BUSWIDTH_8_BYTES | DMA_SLAVE_BUSWIDTH_16_BYTES |
>  		DMA_SLAVE_BUSWIDTH_32_BYTES | DMA_SLAVE_BUSWIDTH_64_BYTES;
> +	const struct rcar_dmac_of_data *data;
> +	struct rcar_dmac_chan *chan;
>  	struct dma_device *engine;
>  	struct rcar_dmac *dmac;
> -	const struct rcar_dmac_of_data *data;
>  	unsigned int i;
>  	int ret;
>  
> @@ -1916,11 +1917,8 @@ static int rcar_dmac_probe(struct platform_device *pdev)
>  
>  	INIT_LIST_HEAD(&engine->channels);
>  
> -	for (i = 0; i < dmac->n_channels; ++i) {
> -		if (!(dmac->channels_mask & BIT(i)))
> -			continue;
> -
> -		ret = rcar_dmac_chan_probe(dmac, &dmac->channels[i], data, i);
> +	for_each_rcar_dmac_chan(i, chan, dmac) {
> +		ret = rcar_dmac_chan_probe(dmac, chan, data, i);
>  		if (ret < 0)
>  			goto error;
>  	}

-- 
Regards,

Laurent Pinchart