Re: [PATCH 4/9] soc: apple: Add SART driver

From: Alyssa Rosenzweig <alyssa@rosenzweig.io>
To: Sven Peter <sven@svenpeter.dev>
Cc: Hector Martin <marcan@marcan.st>,
	Rob Herring <robh+dt@kernel.org>, Arnd Bergmann <arnd@arndb.de>,
	Keith Busch <kbusch@kernel.org>, Jens Axboe <axboe@fb.com>,
	Christoph Hellwig <hch@lst.de>, Sagi Grimberg <sagi@grimberg.me>,
	Marc Zyngier <maz@kernel.org>,
	devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, linux-nvme@lists.infradead.org
Subject: Re: [PATCH 4/9] soc: apple: Add SART driver
Date: Mon, 21 Mar 2022 17:17:14 +0000	[thread overview]
Message-ID: <YjizGmjlAhyU6bC6@rosenzweig.io> (raw)
In-Reply-To: <20220321165049.35985-5-sven@svenpeter.dev>

> +/*
> + * Adds the region [paddr, paddr+size] to the DMA allow list.
> + *
> + * @sart: SART reference
> + * @paddr: Start address of the region to be used for DMA
> + * @size: Size of the region to be used for DMA.
> + */
> +int apple_sart_add_allowed_region(struct apple_sart *sart, phys_addr_t paddr,
> +				  size_t size);
> +
> +/*
> + * Removes the region [paddr, paddr+size] from the DMA allow list.
> + *
> + * Note that exact same paddr and size used for apple_sart_add_allowed_region
> + * have to be passed.
> + *
> + * @sart: SART reference
> + * @paddr: Start address of the region no longer used for DMA
> + * @size: Size of the region no longer used for DMA.
> + */
> +int apple_sart_remove_allowed_region(struct apple_sart *sart, phys_addr_t paddr,
> +				     size_t size);

Might it be simpler for add_allowed_region to return a handle that
remove_allowed_region takes instead of paddr+size? Then
remove_allowed_region doesn't have to walk anything, and the requirement
to use the same paddr/size is implicit.