Re: [PATCH 3/4] i3c: master: svc: add support for slave to stop returning data

Miquel Raynal
2021-07-15T22:56:01Z

Hi Clark,

Clark Wang <xiaoning.wang@nxp.com> wrote on Thu, 15 Jul 2021 16:24:12
+0800:

> When i3c controller reads data from slave device, slave device can stop
> returning data with an ACK after any byte.
> Add this support for svc i3c controller. Otherwise, it will go TIMEOUT
> error path when the slave device ends the read operation early.

Is this part of the I3C specification? I am not aware about it.

> Signed-off-by: Clark Wang <xiaoning.wang@nxp.com>
> ---
> drivers/i3c/master/svc-i3c-master.c | 28 ++++++++++++++++++++--------
> 1 file changed, 20 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/i3c/master/svc-i3c-master.c b/drivers/i3c/master/svc-i3c-master.c
> index 9d80435638ea..892e57fec4b0 100644
> --- a/drivers/i3c/master/svc-i3c-master.c
> +++ b/drivers/i3c/master/svc-i3c-master.c
> @@ -865,7 +865,7 @@ static int svc_i3c_master_read(struct svc_i3c_master *master,
> u8 *in, unsigned int len)
> {
> int offset = 0, i, ret;
> - u32 mdctrl;
> + u32 mdctrl, mstatus;
>
> while (offset < len) {
> unsigned int count;
> @@ -874,8 +874,15 @@ static int svc_i3c_master_read(struct svc_i3c_master *master,
> mdctrl,
> !(mdctrl & SVC_I3C_MDATACTRL_RXEMPTY),
> 0, 1000);
> - if (ret)
> - return ret;
> + if (ret) {
> + ret = readl_poll_timeout(master->regs + SVC_I3C_MSTATUS,
> + mstatus, SVC_I3C_MSTATUS_COMPLETE(mstatus),
> + 0, 1000);
> + if (ret)
> + return ret;
> + else
> + return offset;
> + }
>
> count = SVC_I3C_MDATACTRL_RXCOUNT(mdctrl);
> for (i = 0; i < count; i++)
> @@ -884,7 +891,7 @@ static int svc_i3c_master_read(struct svc_i3c_master *master,
> offset += count;
> }
>
> - return 0;
> + return offset;
> }
>
> static int svc_i3c_master_write(struct svc_i3c_master *master,
> @@ -917,7 +924,7 @@ static int svc_i3c_master_write(struct svc_i3c_master *master,
> static int svc_i3c_master_xfer(struct svc_i3c_master *master,
> bool rnw, unsigned int xfer_type, u8 addr,
> u8 *in, const u8 *out, unsigned int xfer_len,
> - unsigned int read_len, bool continued)
> + unsigned int *read_len, bool continued)
> {
> u32 reg;
> int ret;
> @@ -927,7 +934,7 @@ static int svc_i3c_master_xfer(struct svc_i3c_master *master,
> SVC_I3C_MCTRL_IBIRESP_NACK |
> SVC_I3C_MCTRL_DIR(rnw) |
> SVC_I3C_MCTRL_ADDR(addr) |
> - SVC_I3C_MCTRL_RDTERM(read_len),
> + SVC_I3C_MCTRL_RDTERM(*read_len),
> master->regs + SVC_I3C_MCTRL);
>
> ret = readl_poll_timeout(master->regs + SVC_I3C_MSTATUS, reg,
> @@ -939,8 +946,10 @@ static int svc_i3c_master_xfer(struct svc_i3c_master *master,
> ret = svc_i3c_master_read(master, in, xfer_len);
> else
> ret = svc_i3c_master_write(master, out, xfer_len);
> - if (ret)
> + if (ret < 0)
> goto emit_stop;
> + if (rnw)
> + *read_len = ret;
>
> ret = readl_poll_timeout(master->regs + SVC_I3C_MSTATUS, reg,
> SVC_I3C_MSTATUS_COMPLETE(reg), 0, 1000);
> @@ -1012,7 +1021,7 @@ static void svc_i3c_master_start_xfer_locked(struct svc_i3c_master *master)
>
> ret = svc_i3c_master_xfer(master, cmd->rnw, xfer->type,
> cmd->addr, cmd->in, cmd->out,
> - cmd->len, cmd->read_len,
> + cmd->len, &cmd->read_len,
> cmd->continued);
> if (ret)
> break;
> @@ -1141,6 +1150,9 @@ static int svc_i3c_master_send_direct_ccc_cmd(struct svc_i3c_master *master,
> if (!wait_for_completion_timeout(&xfer->comp, msecs_to_jiffies(1000)))
> svc_i3c_master_dequeue_xfer(master, xfer);
>
> + if (cmd->read_len != xfer_len)
> + ccc->dests[0].payload.len = cmd->read_len;
> +
> ret = xfer->ret;
> svc_i3c_master_free_xfer(xfer);
>

Thanks,
Miquèl