From: Vinod Koul <vkoul@kernel.org>
To: Peter Ujfalusi <peter.ujfalusi@ti.com>
Cc: robh+dt@kernel.org, nm@ti.com, ssantosh@kernel.org,
dan.j.williams@intel.com, dmaengine@vger.kernel.org,
linux-arm-kernel@lists.infradead.org, devicetree@vger.kernel.org,
linux-kernel@vger.kernel.org, grygorii.strashko@ti.com,
lokeshvutla@ti.com, t-kristo@ti.com, tony@atomide.com,
j-keerthy@ti.com, vigneshr@ti.com
Subject: Re: [PATCH v7 03/12] dmaengine: doc: Add sections for per descriptor metadata support
Date: Fri, 20 Dec 2019 13:58:10 +0530 [thread overview]
Message-ID: <20191220082810.GJ2536@vkoul-mobl> (raw)
In-Reply-To: <20191209094332.4047-4-peter.ujfalusi@ti.com>
Hi Peter,
On 09-12-19, 11:43, Peter Ujfalusi wrote:
> + Optional: per descriptor metadata
> + ---------------------------------
> + DMAengine provides two ways for metadata support.
> +
> + DESC_METADATA_CLIENT
> +
> + The metadata buffer is allocated/provided by the client driver and it is
> + attached to the descriptor.
> +
> + .. code-block:: c
> +
> + int dmaengine_desc_attach_metadata(struct dma_async_tx_descriptor *desc,
> + void *data, size_t len);
> +
> + DESC_METADATA_ENGINE
> +
> + The metadata buffer is allocated/managed by the DMA driver. The client
and when would it be freed?
> + driver can ask for the pointer, maximum size and the currently used size of
> + the metadata and can directly update or read it.
> +
> + .. code-block:: c
> +
> + void *dmaengine_desc_get_metadata_ptr(struct dma_async_tx_descriptor *desc,
> + size_t *payload_len, size_t *max_len);
> +
> + int dmaengine_desc_set_metadata_len(struct dma_async_tx_descriptor *desc,
> + size_t payload_len);
> +
> + Client drivers can query if a given mode is supported with:
> +
> + .. code-block:: c
> +
> + bool dmaengine_is_metadata_mode_supported(struct dma_chan *chan,
> + enum dma_desc_metadata_mode mode);
> +
> + Depending on the used mode client drivers must follow different flow.
> +
> + DESC_METADATA_CLIENT
> +
> + - DMA_MEM_TO_DEV / DEV_MEM_TO_MEM:
> + 1. prepare the descriptor (dmaengine_prep_*)
> + construct the metadata in the client's buffer
> + 2. use dmaengine_desc_attach_metadata() to attach the buffer to the
> + descriptor
> + 3. submit the transfer
This is simpler, txn finished the metadata would be freed up right?
> + - DMA_DEV_TO_MEM:
> + 1. prepare the descriptor (dmaengine_prep_*)
> + 2. use dmaengine_desc_attach_metadata() to attach the buffer to the
> + descriptor
> + 3. submit the transfer
> + 4. when the transfer is completed, the metadata should be available in the
> + attached buffer
and when and how would driver free that up :)
> +
> + DESC_METADATA_ENGINE
> +
> + - DMA_MEM_TO_DEV / DEV_MEM_TO_MEM:
> + 1. prepare the descriptor (dmaengine_prep_*)
> + 2. use dmaengine_desc_get_metadata_ptr() to get the pointer to the
> + engine's metadata area
> + 3. update the metadata at the pointer
> + 4. use dmaengine_desc_set_metadata_len() to tell the DMA engine the
> + amount of data the client has placed into the metadata buffer
> + 5. submit the transfer
> + - DMA_DEV_TO_MEM:
> + 1. prepare the descriptor (dmaengine_prep_*)
> + 2. submit the transfer
> + 3. on transfer completion, use dmaengine_desc_get_metadata_ptr() to get the
> + pointer to the engine's metadata area
> + 4. Read out the metadata from the pointer
> +
> + .. note::
> +
> + Mixed use of DESC_METADATA_CLIENT / DESC_METADATA_ENGINE is not allowed,
> + client drivers must use either of the modes per descriptor.
We should check that if not done already!
--
~Vinod
next prev parent reply other threads:[~2019-12-20 8:28 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-09 9:43 [PATCH v7 00/12] dmaengine/soc: Add Texas Instruments UDMA support Peter Ujfalusi
2019-12-09 9:43 ` [PATCH v7 01/12] bindings: soc: ti: add documentation for k3 ringacc Peter Ujfalusi
2019-12-09 9:43 ` [PATCH v7 02/12] soc: ti: k3: add navss ringacc driver Peter Ujfalusi
2019-12-09 9:43 ` [PATCH v7 03/12] dmaengine: doc: Add sections for per descriptor metadata support Peter Ujfalusi
2019-12-20 8:28 ` Vinod Koul [this message]
2019-12-20 9:52 ` Peter Ujfalusi
2019-12-20 10:14 ` Vinod Koul
2019-12-09 9:43 ` [PATCH v7 04/12] dmaengine: Add metadata_ops for dma_async_tx_descriptor Peter Ujfalusi
2019-12-20 8:32 ` Vinod Koul
2019-12-20 8:48 ` Peter Ujfalusi
2019-12-09 9:43 ` [PATCH v7 05/12] dmaengine: Add support for reporting DMA cached data amount Peter Ujfalusi
2019-12-20 8:37 ` Vinod Koul
2019-12-20 8:49 ` Peter Ujfalusi
2019-12-20 9:57 ` Vinod Koul
2019-12-20 10:13 ` Peter Ujfalusi
2019-12-09 9:43 ` [PATCH v7 06/12] dmaengine: ti: Add cppi5 header for K3 NAVSS/UDMA Peter Ujfalusi
2019-12-20 9:54 ` Vinod Koul
2019-12-20 10:42 ` Peter Ujfalusi
2019-12-23 7:11 ` Peter Ujfalusi
2019-12-09 9:43 ` [PATCH v7 07/12] dmaengine: ti: k3 PSI-L remote endpoint configuration Peter Ujfalusi
2019-12-09 9:43 ` [PATCH v7 08/12] dt-bindings: dma: ti: Add document for K3 UDMA Peter Ujfalusi
2019-12-23 6:53 ` Vinod Koul
2019-12-09 9:43 ` [PATCH v7 09/12] dmaengine: ti: New driver " Peter Ujfalusi
2019-12-23 7:34 ` Vinod Koul
2019-12-23 8:59 ` Peter Ujfalusi
2019-12-23 11:26 ` Vinod Koul
2019-12-09 9:43 ` [PATCH v7 10/12] dmaengine: ti: k3-udma: Add glue layer for non DMAengine users Peter Ujfalusi
2019-12-09 9:43 ` [PATCH v7 11/12] firmware: ti_sci: rm: Add support for tx_tdtype parameter for tx channel Peter Ujfalusi
2019-12-11 10:24 ` Tero Kristo
2019-12-09 9:43 ` [PATCH v7 12/12] dmaengine: ti: k3-udma: Wait for peer teardown completion if supported Peter Ujfalusi
2019-12-11 10:43 ` [PATCH v7 00/12] dmaengine/soc: Add Texas Instruments UDMA support Keerthy
2019-12-12 8:46 ` Peter Ujfalusi
2019-12-12 10:55 ` Tero Kristo
2019-12-12 10:57 ` Tero Kristo
2019-12-16 10:05 ` Peter Ujfalusi
2019-12-12 18:01 ` Grygorii Strashko
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