Messages in this thread | | | Subject | Re: [PATCH 5/6] soundwire: qcom: update register read/write routine | From | Pierre-Louis Bossart <> | Date | Fri, 29 Jan 2021 13:33:30 -0600 |
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On 1/29/21 11:32 AM, Srinivas Kandagatla wrote: > In the existing code every soundwire register read and register write > are kinda blocked. Each of these are using a special command id that
what does 'kinda blocked' mean?
> generates interrupt after it successfully finishes. This is really > overhead, limiting and not really necessary unless we are doing > something special. > > We can simply read/write the fifo that should also give exactly > what we need! This will also allow to read/write registers in > interrupt context, which was not possible with the special > command approach.
This is really unclear, sorry.
> + if (id != SWR_BROADCAST_CMD_ID) { > + if (id < 14) > + id += 1; > + else > + id = 0;
that is really odd. if id=13 (group2) then id becomes 14 (master address). A comment is really needed here.
> + if (cmd_id == SWR_BROADCAST_CMD_ID) { > + /* > + * sleep for 10ms for MSM soundwire variant to allow broadcast > + * command to complete.
that's also super-odd. There is nothing in SoundWire that makes any difference between a regular and a broadcast command. they all complete in the same time (a frame). > + */ > + ret = wait_for_completion_timeout(&swrm->broadcast, (2 * HZ/10));
is this 10ms really or dependent on CONFIG_HZ?
> + if (!ret) > + ret = SDW_CMD_IGNORED; > + else > + ret = SDW_CMD_OK;
no CMD_FAILED support?
> +static int qcom_swrm_cmd_fifo_rd_cmd(struct qcom_swrm_ctrl *swrm, > + u8 dev_addr, u16 reg_addr, > + u32 len, u8 *rval) > +{ > + u32 val; > + u32 retry_attempt = 0; > + u32 cmd_data; > + int ret = SDW_CMD_OK; > + > + mutex_lock(&swrm->io_lock); > + val = swrm_get_packed_reg_val(&swrm->rcmd_id, len, dev_addr, reg_addr); > + > + /* wait for FIFO RD to complete to avoid overflow */ > + usleep_range(100, 105); > + swrm->reg_write(swrm, SWRM_CMD_FIFO_RD_CMD, val); > + /* wait for FIFO RD CMD complete to avoid overflow */ > + usleep_range(250, 255); > + > +retry_read: > + > + swrm->reg_read(swrm, SWRM_CMD_FIFO_RD_FIFO_ADDR, &cmd_data); > + rval[0] = cmd_data & 0xFF; > + > + if ((((cmd_data) & 0xF00) >> 8) != swrm->rcmd_id) { > + if (retry_attempt < MAX_FIFO_RD_FAIL_RETRY) { > + /* wait 500 us before retry on fifo read failure */ > + usleep_range(500, 505); > + if (retry_attempt == (MAX_FIFO_RD_FAIL_RETRY - 1)) { > + swrm->reg_write(swrm, SWRM_CMD_FIFO_CMD, 0x1); > + swrm->reg_write(swrm, SWRM_CMD_FIFO_RD_CMD, val); > + } > + retry_attempt++; > + goto retry_read; > + } else { > + dev_err(swrm->dev, > + "failed to read fifo: reg: 0x%x, \ > + rcmd_id: 0x%x, dev_num: 0x%x, cmd_data: 0x%x\n", > + reg_addr, swrm->rcmd_id, > + dev_addr, cmd_data); > + ret = SDW_CMD_IGNORED; > + } > }
the flow seems complicated with multiple tests and goto? Can this be simplified?
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