Re: [PATCH v6 3/5] i3c: master: svc: Add basic HDR mode support

Andy Shevchenko
2025-10-23T08:30:01Z

On Tue, Oct 14, 2025 at 12:40:02PM -0400, Frank Li wrote:
> Add basic HDR mode support for the svs I3C master driver.
>
> Only support for private transfers and does not support sending CCC
> commands in HDR mode.
>
> Key differences:
> - HDR uses commands (0x00-0x7F for write, 0x80-0xFF for read) to
> distinguish transfer direction.
> - HDR read/write commands must be written to FIFO before issuing the I3C
> address command. The hardware automatically sends the standard CCC command
> to enter HDR mode.
> - HDR exit pattern must be sent instead of send a stop after transfer
> completion.
> - Read/write data size must be an even number.

...

> +static void svc_i3c_master_emit_force_exit(struct svc_i3c_master *master)
> +{
> + u32 reg = 0;

Useless.

> + writel(SVC_I3C_MCTRL_REQUEST_FORCE_EXIT, master->regs + SVC_I3C_MCTRL);
> + readl_poll_timeout(master->regs + SVC_I3C_MSTATUS, reg,
> + SVC_I3C_MSTATUS_MCTRLDONE(reg), 0, 1000);

No error checks? Why is it okay?
Why is the first parameter 0 while it's not an _atomic() call?

> + udelay(1);

No explanations given. Also is it really need to be atomic? If not, use
fsleep() and it will choose the best suitable API under the hood.

> }

...

> + if (xfer_type == SVC_I3C_MCTRL_TYPE_DDR) {
> + /* DDR command need prefill into FIFO */
> + writel(rnw_cmd, master->regs + SVC_I3C_MWDATAB);
> + if (!rnw) {
> + /* write data also need prefill into FIFO */
> + ret = svc_i3c_master_write(master, out, xfer_len);
> + if (ret)
> + goto emit_stop;
> + }

The indentation here is a mess.

> + }

--
With Best Regards,
Andy Shevchenko