From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 506D75821A; Thu, 21 Dec 2023 16:13:15 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="LQbBRiV2" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C4218C433CB; Thu, 21 Dec 2023 16:13:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1703175195; bh=KVesujFyxk8g+PzjFWaKsdIwlbPbsy9MmO8ani2Ia+Q=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=LQbBRiV2NxFUlEtQl9y5+GPe98N7iyUbmlEtAJYC69/jn5YMiEp1tfhq/lyTEFOGn fdRPQMVVnE1xFlCoa3XIHzGdf2/7FfSm0loSmFlaeWDW8gPEfT2ZfXlukBd0aLLy3l qyiWwUipdrLQHBBDY5IUzQV8xVXYAc33ENr9DFcqCc6Y9YMfJgrKshGdN+bVjWdwBy bIdM8FsrbnbjT4D4d0E8htI1K0bodi1FkJ9SREYSRULMgFLxVKZsBEwJ/J/v8aTcye 9aqYrHcTGq0q68Eln1R4BfbgPOBj3TOIWa44/Gr7WzeQQ5Mx7DQgLLYpNiUfQp9Uhz 3GYgpXjn6n3QA== Date: Thu, 21 Dec 2023 16:12:58 +0000 From: Jonathan Cameron To: Paul Cercueil Cc: Lars-Peter Clausen , Sumit Semwal , Christian =?UTF-8?B?S8O2bmln?= , Vinod Koul , Jonathan Corbet , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, dmaengine@vger.kernel.org, linux-iio@vger.kernel.org, linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org, Nuno =?UTF-8?B?U8Oh?= , Michael Hennerich Subject: Re: [PATCH v5 7/8] iio: buffer-dmaengine: Support new DMABUF based userspace API Message-ID: <20231221161258.056f5ce4@jic23-huawei> In-Reply-To: <20231219175009.65482-8-paul@crapouillou.net> References: <20231219175009.65482-1-paul@crapouillou.net> <20231219175009.65482-8-paul@crapouillou.net> X-Mailer: Claws Mail 4.2.0 (GTK 3.24.38; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Tue, 19 Dec 2023 18:50:08 +0100 Paul Cercueil wrote: > Use the functions provided by the buffer-dma core to implement the > DMABUF userspace API in the buffer-dmaengine IIO buffer implementation. > > Since we want to be able to transfer an arbitrary number of bytes and > not necesarily the full DMABUF, the associated scatterlist is converted > to an array of DMA addresses + lengths, which is then passed to > dmaengine_prep_slave_dma_array(). > > Signed-off-by: Paul Cercueil One question inline. Otherwise looks fine to me. J > > --- > v3: Use the new dmaengine_prep_slave_dma_array(), and adapt the code to > work with the new functions introduced in industrialio-buffer-dma.c. > > v5: - Use the new dmaengine_prep_slave_dma_vec(). > - Restrict to input buffers, since output buffers are not yet > supported by IIO buffers. > --- > .../buffer/industrialio-buffer-dmaengine.c | 52 ++++++++++++++++--- > 1 file changed, 46 insertions(+), 6 deletions(-) > > diff --git a/drivers/iio/buffer/industrialio-buffer-dmaengine.c b/drivers/iio/buffer/industrialio-buffer-dmaengine.c > index 5f85ba38e6f6..825d76a24a67 100644 > --- a/drivers/iio/buffer/industrialio-buffer-dmaengine.c > +++ b/drivers/iio/buffer/industrialio-buffer-dmaengine.c > @@ -64,15 +64,51 @@ static int iio_dmaengine_buffer_submit_block(struct iio_dma_buffer_queue *queue, > struct dmaengine_buffer *dmaengine_buffer = > iio_buffer_to_dmaengine_buffer(&queue->buffer); > struct dma_async_tx_descriptor *desc; > + unsigned int i, nents; > + struct scatterlist *sgl; > + struct dma_vec *vecs; > + size_t max_size; > dma_cookie_t cookie; > + size_t len_total; > > - block->bytes_used = min(block->size, dmaengine_buffer->max_size); > - block->bytes_used = round_down(block->bytes_used, > - dmaengine_buffer->align); > + if (queue->buffer.direction != IIO_BUFFER_DIRECTION_IN) { > + /* We do not yet support output buffers. */ > + return -EINVAL; > + } > > - desc = dmaengine_prep_slave_single(dmaengine_buffer->chan, > - block->phys_addr, block->bytes_used, DMA_DEV_TO_MEM, > - DMA_PREP_INTERRUPT); > + if (block->sg_table) { > + sgl = block->sg_table->sgl; > + nents = sg_nents_for_len(sgl, block->bytes_used); Are we guaranteed the length in the sglist is enough? If not this can return an error code. > + > + vecs = kmalloc_array(nents, sizeof(*vecs), GFP_KERNEL); > + if (!vecs) > + return -ENOMEM; > + > + len_total = block->bytes_used; > + > + for (i = 0; i < nents; i++) { > + vecs[i].addr = sg_dma_address(sgl); > + vecs[i].len = min(sg_dma_len(sgl), len_total); > + len_total -= vecs[i].len; > + > + sgl = sg_next(sgl); > + } > + > + desc = dmaengine_prep_slave_dma_vec(dmaengine_buffer->chan, > + vecs, nents, DMA_DEV_TO_MEM, > + DMA_PREP_INTERRUPT); > + kfree(vecs); > + } else { > + max_size = min(block->size, dmaengine_buffer->max_size); > + max_size = round_down(max_size, dmaengine_buffer->align); > + block->bytes_used = max_size; > + > + desc = dmaengine_prep_slave_single(dmaengine_buffer->chan, > + block->phys_addr, > + block->bytes_used, > + DMA_DEV_TO_MEM, > + DMA_PREP_INTERRUPT); > + } > if (!desc) > return -ENOMEM; >