Re: [PATCH v4 06/20] mtd: nand: qcom: allocate BAM transaction

[Archit Taneja]

On 08/11/2017 05:09 PM, Abhishek Sahu wrote:
> - The BAM transaction is the core data structure which will be used
>    for all the data transfers in QPIC NAND. Since the core framework
>    in nand_base.c is serializing all the NAND requests so allocating
>    BAM transaction before every transfer will be overhead. The memory
>    for it be allocated during probe time and before every transfer,
>    it will be cleared.
>
> - The BAM transaction contains the array of
>    command and data scatter gather list and indexes. For
>    every transfer, all the resource will be taken from BAM
>    transaction.
>
> - The size of the buffer used for BAM transactions
>    is calculated based on the NAND device with the maximum page size,
>    among all the devices connected to the
>    controller.

Reviewed-by: Archit Taneja <architt@xxxxxxxxxxxxxx>

Thanks,
Archit

> Signed-off-by: Abhishek Sahu <absahu@xxxxxxxxxxxxxx>
> ---
>   drivers/mtd/nand/qcom_nandc.c | 94 +++++++++++++++++++++++++++++++++++++++++++
>   1 file changed, 94 insertions(+)
>
> diff --git a/drivers/mtd/nand/qcom_nandc.c b/drivers/mtd/nand/qcom_nandc.c
> index 590fc1d..4f8306e 100644
> --- a/drivers/mtd/nand/qcom_nandc.c
> +++ b/drivers/mtd/nand/qcom_nandc.c
> @@ -177,6 +177,32 @@
>   #define	ECC_BCH_4BIT	BIT(2)
>   #define	ECC_BCH_8BIT	BIT(3)
>   
> +#define QPIC_PER_CW_CMD_SGL		32
> +#define QPIC_PER_CW_DATA_SGL		8
> +
> +/*
> + * This data type corresponds to the BAM transaction which will be used for all
> + * NAND transfers.
> + * @cmd_sgl - sgl for NAND BAM command pipe
> + * @data_sgl - sgl for NAND BAM consumer/producer pipe
> + * @cmd_sgl_pos - current index in command sgl.
> + * @cmd_sgl_start - start index in command sgl.
> + * @tx_sgl_pos - current index in data sgl for tx.
> + * @tx_sgl_start - start index in data sgl for tx.
> + * @rx_sgl_pos - current index in data sgl for rx.
> + * @rx_sgl_start - start index in data sgl for rx.
> + */
> +struct bam_transaction {
> +	struct scatterlist *cmd_sgl;
> +	struct scatterlist *data_sgl;
> +	u32 cmd_sgl_pos;
> +	u32 cmd_sgl_start;
> +	u32 tx_sgl_pos;
> +	u32 tx_sgl_start;
> +	u32 rx_sgl_pos;
> +	u32 rx_sgl_start;
> +};
> +
>   struct desc_info {
>   	struct list_head node;
>   
> @@ -243,6 +269,8 @@ struct nandc_regs {
>    * @cmd1/vld:			some fixed controller register values
>    * @props:			properties of current NAND controller,
>    *				initialized via DT match data
> + * @max_cwperpage:		maximum QPIC codewords required. calculated
> + *				from all connected NAND devices pagesize
>    */
>   struct qcom_nand_controller {
>   	struct nand_hw_control controller;
> @@ -273,11 +301,13 @@ struct qcom_nand_controller {
>   	};
>   
>   	struct list_head desc_list;
> +	struct bam_transaction *bam_txn;
>   
>   	u8		*data_buffer;
>   	int		buf_size;
>   	int		buf_count;
>   	int		buf_start;
> +	unsigned int	max_cwperpage;
>   
>   	__le32 *reg_read_buf;
>   	dma_addr_t reg_read_dma;
> @@ -350,6 +380,44 @@ struct qcom_nandc_props {
>   	bool is_bam;
>   };
>   
> +/* Frees the BAM transaction memory */
> +static void free_bam_transaction(struct qcom_nand_controller *nandc)
> +{
> +	struct bam_transaction *bam_txn = nandc->bam_txn;
> +
> +	devm_kfree(nandc->dev, bam_txn);
> +}
> +
> +/* Allocates and Initializes the BAM transaction */
> +static struct bam_transaction *
> +alloc_bam_transaction(struct qcom_nand_controller *nandc)
> +{
> +	struct bam_transaction *bam_txn;
> +	size_t bam_txn_size;
> +	unsigned int num_cw = nandc->max_cwperpage;
> +	void *bam_txn_buf;
> +
> +	bam_txn_size =
> +		sizeof(*bam_txn) + num_cw *
> +		((sizeof(*bam_txn->cmd_sgl) * QPIC_PER_CW_CMD_SGL) +
> +		(sizeof(*bam_txn->data_sgl) * QPIC_PER_CW_DATA_SGL));
> +
> +	bam_txn_buf = devm_kzalloc(nandc->dev, bam_txn_size, GFP_KERNEL);
> +	if (!bam_txn_buf)
> +		return NULL;
> +
> +	bam_txn = bam_txn_buf;
> +	bam_txn_buf += sizeof(*bam_txn);
> +
> +	bam_txn->cmd_sgl = bam_txn_buf;
> +	bam_txn_buf +=
> +		sizeof(*bam_txn->cmd_sgl) * QPIC_PER_CW_CMD_SGL * num_cw;
> +
> +	bam_txn->data_sgl = bam_txn_buf;
> +
> +	return bam_txn;
> +}
> +
>   static inline struct qcom_nand_host *to_qcom_nand_host(struct nand_chip *chip)
>   {
>   	return container_of(chip, struct qcom_nand_host, chip);
> @@ -1920,6 +1988,8 @@ static int qcom_nand_host_setup(struct qcom_nand_host *host)
>   	mtd_set_ooblayout(mtd, &qcom_nand_ooblayout_ops);
>   
>   	cwperpage = mtd->writesize / ecc->size;
> +	nandc->max_cwperpage = max_t(unsigned int, nandc->max_cwperpage,
> +				     cwperpage);
>   
>   	/*
>   	 * DATA_UD_BYTES varies based on whether the read/write command protects
> @@ -2054,6 +2124,20 @@ static int qcom_nandc_alloc(struct qcom_nand_controller *nandc)
>   			dev_err(nandc->dev, "failed to request cmd channel\n");
>   			return -ENODEV;
>   		}
> +
> +		/*
> +		 * Initially allocate BAM transaction to read ONFI param page.
> +		 * After detecting all the devices, this BAM transaction will
> +		 * be freed and the next BAM tranasction will be allocated with
> +		 * maximum codeword size
> +		 */
> +		nandc->max_cwperpage = 1;
> +		nandc->bam_txn = alloc_bam_transaction(nandc);
> +		if (!nandc->bam_txn) {
> +			dev_err(nandc->dev,
> +				"failed to allocate bam transaction\n");
> +			return -ENOMEM;
> +		}
>   	} else {
>   		nandc->chan = dma_request_slave_channel(nandc->dev, "rxtx");
>   		if (!nandc->chan) {
> @@ -2211,6 +2295,16 @@ static int qcom_probe_nand_devices(struct qcom_nand_controller *nandc)
>   	if (list_empty(&nandc->host_list))
>   		return -ENODEV;
>   
> +	if (nandc->props->is_bam) {
> +		free_bam_transaction(nandc);
> +		nandc->bam_txn = alloc_bam_transaction(nandc);
> +		if (!nandc->bam_txn) {
> +			dev_err(nandc->dev,
> +				"failed to allocate bam transaction\n");
> +			return -ENOMEM;
> +		}
> +	}
> +
>   	list_for_each_entry_safe(host, tmp, &nandc->host_list, node) {
>   		ret = qcom_nand_mtd_register(nandc, host, child);
>   		if (ret) {

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