[PATCH v1 1/7] dt-bindings: stm32-dma: Add DMA/MDMA chaining support bindings
robh at kernel.org
Wed Sep 26 13:21:12 PDT 2018
On Tue, Sep 11, 2018 at 09:26:54AM +0200, Pierre-Yves MORDRET wrote:
> This patch adds dma bindings to support DMA/MDMA chaining transfer.
> 1 bit is to manage both DMA FIFO Threshold
> 1 bit is to manage DMA/MDMA Chaining features.
> 2 bits are used to specify SDRAM size to use for DMA/MDMA chaining.
> The size in bytes of a certain order is given by the formula:
> (2 ^ order) * PAGE_SIZE.
> The order is given by those 2 bits.
> For cyclic, whether chaining is chosen, any value above 1 can be set :
> SRAM buffer size will rely on period size and not on this DT value.
> Signed-off-by: Pierre-Yves MORDRET <pierre-yves.mordret at st.com>
> Version history:
> * Initial
> .../devicetree/bindings/dma/stm32-dma.txt | 32 +++++++++++++++++++---
> 1 file changed, 28 insertions(+), 4 deletions(-)
> diff --git a/Documentation/devicetree/bindings/dma/stm32-dma.txt b/Documentation/devicetree/bindings/dma/stm32-dma.txt
> index c5f5190..163be09 100644
> --- a/Documentation/devicetree/bindings/dma/stm32-dma.txt
> +++ b/Documentation/devicetree/bindings/dma/stm32-dma.txt
> @@ -17,6 +17,12 @@ Optional properties:
> - resets: Reference to a reset controller asserting the DMA controller
> - st,mem2mem: boolean; if defined, it indicates that the controller supports
> memory-to-memory transfer
> +- dmas: A list of eight dma specifiers, one for each entry in dma-names.
> + Refer to stm32-mdma.txt for more details.
> +- dma-names: should contain "ch0", "ch1", "ch2", "ch3", "ch4", "ch5", "ch6" and
> + "ch7" and represents each STM32 DMA channel connected to a STM32 MDMA one.
> +- memory-region : phandle to a node describing memory to be used for
> + M2M intermediate transfer between DMA and MDMA.
> @@ -36,6 +42,16 @@ Example:
> resets = <&rcc 150>;
> dma-requests = <8>;
> + dmas = <&mdma1 8 0x10 0x1200000a 0x40026408 0x00000020 1>,
> + <&mdma1 9 0x10 0x1200000a 0x40026408 0x00000800 1>,
> + <&mdma1 10 0x10 0x1200000a 0x40026408 0x00200000 1>,
> + <&mdma1 11 0x10 0x1200000a 0x40026408 0x08000000 1>,
> + <&mdma1 12 0x10 0x1200000a 0x4002640C 0x00000020 1>,
> + <&mdma1 13 0x10 0x1200000a 0x4002640C 0x00000800 1>,
> + <&mdma1 14 0x10 0x1200000a 0x4002640C 0x00200000 1>,
> + <&mdma1 15 0x10 0x1200000a 0x4002640C 0x08000000 1>;
> + dma-names = "ch0", "ch1", "ch2", "ch3", "ch4", "ch5", "ch6", "ch7";
> + memory-region = <&sram_dmapool>;
> * DMA client
> @@ -62,13 +78,21 @@ channel: a phandle to the DMA controller plus the following four integer cells:
> 0x1: medium
> 0x2: high
> 0x3: very high
> -4. A 32bit bitfield value specifying DMA features which are device dependent:
> +4. A bitfield value specifying DMA features which are device dependent:
It's still a 32-bit value, right?
> -bit 0-1: DMA FIFO threshold selection
> 0x0: 1/4 full FIFO
> 0x1: 1/2 full FIFO
> 0x2: 3/4 full FIFO
> 0x3: full FIFO
> + -bit 2: Intermediate M2M transfer from/to DDR to/from SRAM throughout MDMA
> + 0: MDMA not used to generate an intermediate M2M transfer
> + 1: MDMA used to generate an intermediate M2M transfer.
> + -bit 3-4: indicated SRAM Buffer size in (2^order)*PAGE_SIZE.
What's PAGE_SIZE? That's not defined for DT.
> + Order is given by those 2 bits starting at 0.
> + Valid only whether Intermediate M2M transfer is set.
> + For cyclic, whether Intermediate M2M transfer is chosen, any value can
> + be set: SRAM buffer size will rely on period size and not on this DT
> + value.
> @@ -77,7 +101,7 @@ Example:
> reg = <0x40011000 0x400>;
> interrupts = <37>;
> clocks = <&clk_pclk2>;
> - dmas = <&dma2 2 4 0x10400 0x3>,
> - <&dma2 7 5 0x10200 0x3>;
> + dmas = <&dma2 2 4 0x10400 0x1>,
> + <&dma2 7 5 0x10200 0x1>;
> dma-names = "rx", "tx";
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