[PATCH 1/1] i3c: master: svc: skip address resend on repeat START
Miquel Raynal
miquel.raynal at bootlin.com
Wed Apr 23 00:17:43 PDT 2025
On 16/04/2025 at 12:47:50 -04, Frank Li <Frank.Li at nxp.com> wrote:
> According to the I3C specification, address arbitration only happens during
> the START. Repeated START do not initiate arbitration, and In-Band
> Interrupts (IBIs) cannot occur at this stage.
>
> Resending the address upon a NACK in a repeat START is therefore redundant
> and unnecessary. Avoid redundant retries, improving efficiency and ensuring
> protocol compliance.
>
> Signed-off-by: Frank Li <Frank.Li at nxp.com>
> ---
> drivers/i3c/master/svc-i3c-master.c | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/i3c/master/svc-i3c-master.c b/drivers/i3c/master/svc-i3c-master.c
> index 85e16de208d3b..5212c2cc6855f 100644
> --- a/drivers/i3c/master/svc-i3c-master.c
> +++ b/drivers/i3c/master/svc-i3c-master.c
> @@ -1281,9 +1281,9 @@ 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 *actual_len, bool continued)
> + unsigned int *actual_len, bool continued, bool repeat_start)
> {
> - int retry = 2;
> + int retry = repeat_start ? 1 : 2;
> u32 reg;
> int ret;
>
> @@ -1468,7 +1468,7 @@ 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->actual_len,
> - cmd->continued);
> + cmd->continued, !!i);
Could we just pass 'i' here? Or maybe 'i > 0' which might be even clearer.
> /* cmd->xfer is NULL if I2C or CCC transfer */
> if (cmd->xfer)
> cmd->xfer->actual_len = cmd->actual_len;
Thanks,
Miquèl
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