From: Charles Boyer <Charles.Boyer@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@fii-usa.com>
Signed-off-by: Vivekanand Veeracholan <vveerach@google.com>
Signed-off-by: Tyrone Ting <kfting@nuvoton.com>
Reviewed-by: Tali Perry <tali.perry1@gmail.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 fcecb098298f..55348308b992 100644
--- a/drivers/i2c/busses/i2c-npcm7xx.c
+++ b/drivers/i2c/busses/i2c-npcm7xx.c
@@ -1925,6 +1925,12 @@ 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

On Fri, Oct 11, 2024 at 01:52:31PM +0800, Tyrone Ting wrote:
> From: Charles Boyer <Charles.Boyer@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.

...

> +#if IS_ENABLED(CONFIG_I2C_SLAVE)
> +		/* reenable slave if it was enabled */
> +		if (bus->slave)
> +			iowrite8((bus->slave->addr & 0x7F) | NPCM_I2CADDR_SAEN,

GENMASK()?
But why do we need it? Do we expect this to be 10-bit address or...?

> +				 bus->reg + NPCM_I2CADDR1);
> +#endif

-- 
With Best Regards,
Andy Shevchenko

Hi Andy:

Thank you for your feedback.

Andy Shevchenko <andriy.shevchenko@linux.intel.com> 於 2024年10月11日 週五 下午7:02寫道：
>
> On Fri, Oct 11, 2024 at 01:52:31PM +0800, Tyrone Ting wrote:
> > From: Charles Boyer <Charles.Boyer@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.
>
> ...
>
> > +#if IS_ENABLED(CONFIG_I2C_SLAVE)
> > +             /* reenable slave if it was enabled */
> > +             if (bus->slave)
> > +                     iowrite8((bus->slave->addr & 0x7F) | NPCM_I2CADDR_SAEN,
>
> GENMASK()?
> But why do we need it? Do we expect this to be 10-bit address or...?
>

0x7f is going to be removed in the next patch set.

> > +                              bus->reg + NPCM_I2CADDR1);
> > +#endif
>
> --
> With Best Regards,
> Andy Shevchenko
>
>

Thank you.

Regards,
Tyrone