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SubjectRe: [PATCH 02/14] qcom: mtd: nand: add and initialize QPIC DMA resources
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Hi Abhishek,

On 6/29/2017 12:45 PM, Abhishek Sahu wrote:
> 1. The QPIC NAND uses 3 BAM channels: command, data tx and
> data rx while EBI2 NAND uses only single ADM channel.
>
> 2. The EBI2 NAND uses normal register read buffer since this
> buffer will be remapped with dma_map_sg. The QPIC NAND will give
> register read buffer in command descriptor and the command
> descriptor will be mapped with dma_map_sg so the register buffer
> should be DMA coherent.
>
> Signed-off-by: Abhishek Sahu <absahu@codeaurora.org>
> ---
> .../devicetree/bindings/mtd/qcom_nandc.txt | 25 +++--
> drivers/mtd/nand/qcom_nandc.c | 106 ++++++++++++++++-----
> 2 files changed, 99 insertions(+), 32 deletions(-)
>
> diff --git a/Documentation/devicetree/bindings/mtd/qcom_nandc.txt b/Documentation/devicetree/bindings/mtd/qcom_nandc.txt
> index 5d0f7ae..87b9a56 100644
> --- a/Documentation/devicetree/bindings/mtd/qcom_nandc.txt
> +++ b/Documentation/devicetree/bindings/mtd/qcom_nandc.txt
> @@ -9,15 +9,17 @@ Required properties:
> - clock-names: must contain "core" for the core clock and "aon" for the
> always on clock
> - dmas: DMA specifier, consisting of a phandle to the ADM DMA
> - controller node and the channel number to be used for
> - NAND. Refer to dma.txt and qcom_adm.txt for more details
> -- dma-names: must be "rxtx"
> -- qcom,cmd-crci: must contain the ADM command type CRCI block instance
> - number specified for the NAND controller on the given
> - platform
> -- qcom,data-crci: must contain the ADM data type CRCI block instance
> - number specified for the NAND controller on the given
> - platform
> + or BAM DMA controller node and the channel number to
> + be used for NAND. Refer to dma.txt, qcom_adm.txt(ADM)
> + and qcom/bam_dma.txt(BAM) for more details
> +- dma-names: "rxtx" - ADM
> + "tx", "rx", "cmd" - BAM
> +- qcom,cmd-crci: Only required for ADM DMA. must contain the ADM command
> + type CRCI block instance number specified for the NAND
> + controller on the given platform.
> +- qcom,data-crci: Only required for ADM DMA. must contain the ADM data
> + type CRCI block instance number specified for the NAND
> + controller on the given platform.
> - #address-cells: <1> - subnodes give the chip-select number
> - #size-cells: <0>
>
> @@ -95,6 +97,11 @@ nand@79b0000 {
> <&gcc GCC_QPIC_AHB_CLK>;
> clock-names = "core", "aon";
>
> + dmas = <&qpicbam 0>,
> + <&qpicbam 1>,
> + <&qpicbam 2>;
> + dma-names = "tx", "rx", "cmd";
> +
> #address-cells = <1>;
> #size-cells = <0>;
>
> diff --git a/drivers/mtd/nand/qcom_nandc.c b/drivers/mtd/nand/qcom_nandc.c
> index f55f728..520add9 100644
> --- a/drivers/mtd/nand/qcom_nandc.c
> +++ b/drivers/mtd/nand/qcom_nandc.c
> @@ -226,6 +226,7 @@ struct nandc_regs {
> * by upper layers directly
> * @buf_size/count/start: markers for chip->read_buf/write_buf functions
> * @reg_read_buf: local buffer for reading back registers via DMA
> + * @reg_read_buf_phys: contains dma address for register read buffer
> * @reg_read_pos: marker for data read in reg_read_buf
> *
> * @regs: a contiguous chunk of memory for DMA register
> @@ -249,9 +250,19 @@ struct qcom_nand_controller {
> struct clk *core_clk;
> struct clk *aon_clk;
>
> - struct dma_chan *chan;
> - unsigned int cmd_crci;
> - unsigned int data_crci;
> + union {
> + struct {
> + struct dma_chan *tx_chan;
> + struct dma_chan *rx_chan;
> + struct dma_chan *cmd_chan;
> + };
> + struct {
> + struct dma_chan *chan;
> + unsigned int cmd_crci;
> + unsigned int data_crci;
> + };
> + };
> +
> struct list_head desc_list;
>
> u8 *data_buffer;
> @@ -261,6 +272,7 @@ struct qcom_nand_controller {
> int buf_start;
>
> __le32 *reg_read_buf;
> + dma_addr_t reg_read_buf_phys;
> int reg_read_pos;
>
> struct nandc_regs *regs;
> @@ -1956,16 +1968,48 @@ static int qcom_nandc_alloc(struct qcom_nand_controller *nandc)
> if (!nandc->regs)
> return -ENOMEM;
>
> - nandc->reg_read_buf = devm_kzalloc(nandc->dev,
> - MAX_REG_RD * sizeof(*nandc->reg_read_buf),
> - GFP_KERNEL);
> - if (!nandc->reg_read_buf)
> - return -ENOMEM;
>
> - nandc->chan = dma_request_slave_channel(nandc->dev, "rxtx");
> - if (!nandc->chan) {
> - dev_err(nandc->dev, "failed to request slave channel\n");
> - return -ENODEV;
> + if (!nandc->dma_bam_enabled) {
> + nandc->reg_read_buf =
> + devm_kzalloc(nandc->dev, MAX_REG_RD *
> + sizeof(*nandc->reg_read_buf), GFP_KERNEL);
> +
> + if (!nandc->reg_read_buf)
> + return -ENOMEM;
> +
> + nandc->chan = dma_request_slave_channel(nandc->dev, "rxtx");
> + if (!nandc->chan) {
> + dev_err(nandc->dev,
> + "failed to request slave channel\n");
> + return -ENODEV;
> + }
> + } else {
> + nandc->reg_read_buf =
> + dmam_alloc_coherent(nandc->dev, MAX_REG_RD *
> + sizeof(*nandc->reg_read_buf),
> + &nandc->reg_read_buf_phys,
> + GFP_KERNEL);
> +

I think as Archit has commented, do not see a reason for this to be
alloc_coherent change here.

Regards,
Sricharan

--
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