[PATCH v2 7/7] i2c: npcm: Enable slave in eob interrupt

[Tali Perry]

Reviewed-by: Tali Perry <tali.perry1 at gmail.com>

On Fri, Aug 30, 2024 at 6:49 AM Tyrone Ting <warp5tw at gmail.com> wrote:
>
> From: Charles Boyer <Charles.Boyer at fii-usa.com>
>
> Nuvoton slave enable was in user space API call master_xfer, so it is
> subject to delays from the OS scheduler. If the BMC is not enabled for
> slave mode in time for master to send response, then it will NAK the
> address match. Then the PLDM request timeout occurs.
>
> If the slave enable is moved to the EOB interrupt service routine, then
> the BMC can be ready in slave mode by the time it needs to receive a
> response.
>
> Signed-off-by: Charles Boyer <Charles.Boyer at fii-usa.com>
> Signed-off-by: Vivekanand Veeracholan <vveerach at google.com>
> Signed-off-by: Tyrone Ting <kfting at nuvoton.com>
> ---
>  drivers/i2c/busses/i2c-npcm7xx.c | 6 ++++++
>  1 file changed, 6 insertions(+)
>
> diff --git a/drivers/i2c/busses/i2c-npcm7xx.c b/drivers/i2c/busses/i2c-npcm7xx.c
> index cac4ea0b69b8..5bdc1b5895ac 100644
> --- a/drivers/i2c/busses/i2c-npcm7xx.c
> +++ b/drivers/i2c/busses/i2c-npcm7xx.c
> @@ -1781,6 +1781,12 @@ static int npcm_i2c_int_master_handler(struct npcm_i2c *bus)
>             (FIELD_GET(NPCM_I2CCST3_EO_BUSY,
>                        ioread8(bus->reg + NPCM_I2CCST3)))) {
>                 npcm_i2c_irq_handle_eob(bus);
> +#if IS_ENABLED(CONFIG_I2C_SLAVE)
> +               /* reenable slave if it was enabled */
> +               if (bus->slave)
> +                       iowrite8((bus->slave->addr & 0x7F) | NPCM_I2CADDR_SAEN,
> +                                bus->reg + NPCM_I2CADDR1);
> +#endif
>                 return 0;
>         }
>
> --
> 2.34.1
>