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

Archit Taneja
2017-08-16T03:40:25Z

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@codeaurora.org>

Thanks,
Archit

>
> Signed-off-by: Abhishek Sahu <absahu@codeaurora.org>
> ---
> 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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