On 31-03-21, 18:00, Srinivas Kandagatla wrote:
> If we write registers very fast we can endup in a situation where some
> of the writes will be dropped without any notice.
>
> So wait for the fifo space to be available before reading/writing the
> soundwire registers.
>
> Signed-off-by: Srinivas Kandagatla <srinivas.kandaga...@linaro.org>
> ---
> drivers/soundwire/qcom.c | 74 ++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 74 insertions(+)
>
> diff --git a/drivers/soundwire/qcom.c b/drivers/soundwire/qcom.c
> index 6affa3cd4039..9b45717577f2 100644
> --- a/drivers/soundwire/qcom.c
> +++ b/drivers/soundwire/qcom.c
> @@ -24,6 +24,8 @@
> #define SWRM_COMP_CFG_IRQ_LEVEL_OR_PULSE_MSK BIT(1)
> #define SWRM_COMP_CFG_ENABLE_MSK BIT(0)
> #define SWRM_COMP_PARAMS 0x100
> +#define SWRM_COMP_PARAMS_WR_FIFO_DEPTH
> GENMASK(14, 10)
> +#define SWRM_COMP_PARAMS_RD_FIFO_DEPTH
> GENMASK(19, 15)
> #define SWRM_COMP_PARAMS_DOUT_PORTS_MASK GENMASK(4, 0)
> #define SWRM_COMP_PARAMS_DIN_PORTS_MASK
> GENMASK(9, 5)
> #define SWRM_INTERRUPT_STATUS 0x200
> @@ -51,6 +53,8 @@
> #define SWRM_CMD_FIFO_CMD 0x308
> #define SWRM_CMD_FIFO_FLUSH 0x1
> #define SWRM_CMD_FIFO_STATUS 0x30C
> +#define SWRM_RD_CMD_FIFO_CNT_MASK GENMASK(20, 16)
> +#define SWRM_WR_CMD_FIFO_CNT_MASK GENMASK(12, 8)
> #define SWRM_CMD_FIFO_CFG_ADDR 0x314
> #define SWRM_CONTINUE_EXEC_ON_CMD_IGNORE BIT(31)
> #define SWRM_RD_WR_CMD_RETRIES 0x7
> @@ -104,6 +108,7 @@
> #define SWR_BROADCAST_CMD_ID 0x0F
> #define SWR_MAX_CMD_ID 14
> #define MAX_FIFO_RD_RETRY 3
> +#define SWR_OVERFLOW_RETRY_COUNT 30
>
> struct qcom_swrm_port_config {
> u8 si;
> @@ -147,6 +152,8 @@ struct qcom_swrm_ctrl {
> int (*reg_read)(struct qcom_swrm_ctrl *ctrl, int reg, u32 *val);
> int (*reg_write)(struct qcom_swrm_ctrl *ctrl, int reg, int val);
> u32 slave_status;
> + u32 wr_fifo_depth;
> + u32 rd_fifo_depth;
> };
>
> struct qcom_swrm_data {
> @@ -238,6 +245,63 @@ static u32 swrm_get_packed_reg_val(u8 *cmd_id, u8
> cmd_data,
> return val;
> }
>
> +static int swrm_wait_for_rd_fifo_avail(struct qcom_swrm_ctrl *swrm)
> +{
> + u32 fifo_outstanding_cmd, value;
> + u8 fifo_retry_count = SWR_OVERFLOW_RETRY_COUNT;
> +
> + /* Check for fifo underflow during read */
> + swrm->reg_read(swrm, SWRM_CMD_FIFO_STATUS, &value);
> + fifo_outstanding_cmd = FIELD_GET(SWRM_RD_CMD_FIFO_CNT_MASK, value);
> +
> + /* Check number of outstanding commands in fifo before read */
> + if (fifo_outstanding_cmd)
> + return 0;
> +
> + do {
> + usleep_range(500, 510);
> + swrm->reg_read(swrm, SWRM_CMD_FIFO_STATUS, &value);
> + fifo_outstanding_cmd = FIELD_GET(SWRM_RD_CMD_FIFO_CNT_MASK,
> value);
> + if (fifo_outstanding_cmd > 0)
> + break;
> + } while (fifo_retry_count--);
> +
> + if (fifo_outstanding_cmd == 0) {
> + dev_err_ratelimited(swrm->dev, "%s err read underflow\n",
> __func__);
> + return -ENOMEM;
ENOMEM ? that should be EIO, we expected data but didnt get it in read
fifo
> + }
> +
> + return 0;
> +}
> +
> +static int swrm_wait_for_wr_fifo_avail(struct qcom_swrm_ctrl *swrm)
> +{
> + u32 fifo_outstanding_cmd, value;
> + u8 fifo_retry_count = SWR_OVERFLOW_RETRY_COUNT;
> +
> + /* Check for fifo overflow during write */
> + swrm->reg_read(swrm, SWRM_CMD_FIFO_STATUS, &value);
> + fifo_outstanding_cmd = FIELD_GET(SWRM_WR_CMD_FIFO_CNT_MASK, value);
> +
> + /* Check number of outstanding commands in fifo before write */
> + if (fifo_outstanding_cmd != swrm->wr_fifo_depth)
> + return 0;
maybe the comment should say, check for space in write fifo?
> +
> + do {
> + usleep_range(500, 510);
> + swrm->reg_read(swrm, SWRM_CMD_FIFO_STATUS, &value);
> + fifo_outstanding_cmd = FIELD_GET(SWRM_WR_CMD_FIFO_CNT_MASK,
> value);
> + if (fifo_outstanding_cmd < swrm->wr_fifo_depth)
> + break;
> + } while (fifo_retry_count--);
> +
> + if (fifo_outstanding_cmd == swrm->wr_fifo_depth) {
> + dev_err_ratelimited(swrm->dev, "%s err write overflow\n",
> __func__);
> + return -ENOMEM;
EIO or better error code here too
--
~Vinod
