linux-kernel - Re: [PATCH 02/18] dmaengine: bcm2835: Support common dma-channel-mask

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Date: Wed, 5 Jun 2024 11:52:04 -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 02/18] dmaengine: bcm2835: Support common dma-channel-mask

On Fri, May 24, 2024 at 07:26:46PM +0100, Dave Stevenson wrote:
> From: Stefan Wahren <stefan.wahren@...e.com>
> 
> Nowadays there is a generic property for dma-channel-mask in the DMA
> controller binding. So prefer this one instead of the old vendor specific
> one. Print a warning in case the old one is used. Btw use the result of
> of_property_read_u32() as return code in error case.

Use generic 'dma-channel-mask' property. Print a warning in case the
old brcm,dma-channel-mask is used.

Did you update binding doc?

> 
> Signed-off-by: Stefan Wahren <wahrenst@....net>
> Signed-off-by: Dave Stevenson <dave.stevenson@...pberrypi.com>
> ---
>  drivers/dma/bcm2835-dma.c | 19 +++++++++++++------
>  1 file changed, 13 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/dma/bcm2835-dma.c b/drivers/dma/bcm2835-dma.c
> index 9d74fe97452e..528c4593b45a 100644
> --- a/drivers/dma/bcm2835-dma.c
> +++ b/drivers/dma/bcm2835-dma.c
> @@ -941,12 +941,19 @@ static int bcm2835_dma_probe(struct platform_device *pdev)
>  	}
>  
>  	/* Request DMA channel mask from device tree */
> -	if (of_property_read_u32(pdev->dev.of_node,
> -			"brcm,dma-channel-mask",
> -			&chans_available)) {
> -		dev_err(&pdev->dev, "Failed to get channel mask\n");
> -		rc = -EINVAL;
> -		goto err_no_dma;
> +	rc = of_property_read_u32(pdev->dev.of_node, "dma-channel-mask",
> +				  &chans_available);
> +
> +	if (rc) {
> +		/* Try deprecated property */
> +		if (of_property_read_u32(pdev->dev.of_node,
> +					 "brcm,dma-channel-mask",
> +					 &chans_available)) {
> +			dev_err(&pdev->dev, "Failed to get channel mask\n");
> +			goto err_no_dma;
> +		}
> +
> +		dev_warn(&pdev->dev, "brcm,dma-channel-mask deprecated - please update DT\n");
>  	}
>  
>  	/* get irqs for each channel that we support */
> -- 
> 2.34.1
>