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[87.94.132.183]) by smtp.gmail.com with ESMTPSA id 2adb3069b0e04-53e229c1edcsm261651e87.187.2024.12.05.06.25.53 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 05 Dec 2024 06:25:54 -0800 (PST) Message-ID: Date: Thu, 5 Dec 2024 16:25:53 +0200 Precedence: bulk X-Mailing-List: rust-for-linux@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v6 2/2] rust: add dma coherent allocator abstraction. To: Robin Murphy , daniel.almeida@collabora.com Cc: Miguel Ojeda , Alex Gaynor , Boqun Feng , Gary Guo , =?UTF-8?Q?Bj=C3=B6rn_Roy_Baron?= , Benno Lossin , Andreas Hindborg , Alice Ryhl , Trevor Gross , Danilo Krummrich , Valentin Obst , "open list:RUST" , open list , Christoph Hellwig , Marek Szyprowski , airlied@redhat.com, "open list:DMA MAPPING HELPERS" References: <20241205113234.2021442-1-abdiel.janulgue@gmail.com> <20241205113234.2021442-2-abdiel.janulgue@gmail.com> <1c13843f-6929-4bc6-8564-0ec2d964c41d@arm.com> Content-Language: en-US From: Abdiel Janulgue In-Reply-To: <1c13843f-6929-4bc6-8564-0ec2d964c41d@arm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 05/12/2024 15:07, Robin Murphy wrote: >> +    pub fn alloc_coherent( >> +        dev: &Device, >> +        count: usize, >> +        flags: kernel::alloc::Flags, > > Might it be worth adding at least a placeholder type and argument for > "attrs" as well, so there's less churn involved in coming back and > adding it later? Or is the intention to have a separate > dma_alloc_attrs() constructor for such users? > It certainly is possible to include attrs in the constructor using Option: ``` pub fn alloc_coherent( dev: &Device, count: usize, flags: kernel::alloc::Flags, attrs: Option, ) -> Result> { let ret = unsafe { bindings::dma_alloc_attrs( dev.as_raw(), size, &mut dma_handle, flags.as_raw(), attrs.unwrap_or(0), ) }; } ``` So the signature of the constructor could be: let c = CoherentAllocation::alloc_coherent(dev, 4, GFP_KERNEL, None)?; Andreas, Miguel, Daniel, any thoughts? Regards, Abdiel