diff mbox series

[v2,5/7] i2c: npcm: Modify the client address assignment

Message ID 20240830034640.7049-6-kfting@nuvoton.com
State New
Headers show
Series i2c: npcm: Bug fixes read/write operation, checkpatch | expand

Commit Message

Tyrone Ting Aug. 30, 2024, 3:46 a.m. UTC
Store the client address earlier since it's used in the i2c_recover_bus
logic flow.

Fixes: 48acf8292280 ("i2c: Remove redundant comparison in npcm_i2c_reg_slave")
Signed-off-by: Tyrone Ting <kfting@nuvoton.com>
---
 drivers/i2c/busses/i2c-npcm7xx.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Andy Shevchenko Aug. 30, 2024, 7:16 p.m. UTC | #1
On Fri, Aug 30, 2024 at 11:46:38AM +0800, Tyrone Ting wrote:
> Store the client address earlier since it's used in the i2c_recover_bus
> logic flow.

Here no explanation why it's now left-shifted by one bit.
Tyrone Ting Sept. 2, 2024, 1:40 a.m. UTC | #2
Hi Andy:

Thank you for your comments.

Andy Shevchenko <andriy.shevchenko@linux.intel.com> 於 2024年8月31日 週六 上午3:16寫道:
>
> On Fri, Aug 30, 2024 at 11:46:38AM +0800, Tyrone Ting wrote:
> > Store the client address earlier since it's used in the i2c_recover_bus
> > logic flow.
>
> Here no explanation why it's now left-shifted by one bit.

The address is stored from bit 1 to bit 7 in the register for sending
the i2c address later.
I'll write some comments about the left-shifted by one bit behavior
above this modification in next patch set.

>
> --
> With Best Regards,
> Andy Shevchenko
>
>

Thank you.

Regards,
Tyrone
Andy Shevchenko Sept. 2, 2024, 11:54 a.m. UTC | #3
On Mon, Sep 02, 2024 at 09:40:09AM +0800, Tyrone Ting wrote:
> Andy Shevchenko <andriy.shevchenko@linux.intel.com> 於 2024年8月31日 週六 上午3:16寫道:
> > On Fri, Aug 30, 2024 at 11:46:38AM +0800, Tyrone Ting wrote:
> > > Store the client address earlier since it's used in the i2c_recover_bus
> > > logic flow.
> >
> > Here no explanation why it's now left-shifted by one bit.
> 
> The address is stored from bit 1 to bit 7 in the register for sending
> the i2c address later.

Yes, but previously it was stored w/o that shift.

> I'll write some comments about the left-shifted by one bit behavior
> above this modification in next patch set.
Tyrone Ting Sept. 3, 2024, 2:07 a.m. UTC | #4
Hi Andy:

Thank you for your feedback.

Andy Shevchenko <andriy.shevchenko@linux.intel.com> 於 2024年9月2日 週一 下午7:54寫道:
>
> On Mon, Sep 02, 2024 at 09:40:09AM +0800, Tyrone Ting wrote:
> > Andy Shevchenko <andriy.shevchenko@linux.intel.com> 於 2024年8月31日 週六 上午3:16寫道:
> > > On Fri, Aug 30, 2024 at 11:46:38AM +0800, Tyrone Ting wrote:
> > > > Store the client address earlier since it's used in the i2c_recover_bus
> > > > logic flow.
> > >
> > > Here no explanation why it's now left-shifted by one bit.
> >
> > The address is stored from bit 1 to bit 7 in the register for sending
> > the i2c address later.
>
> Yes, but previously it was stored w/o that shift.
>

Previously, the address was stored w/o that shift and with that shift
in the following call to npcm_i2c_master_start_xmit,
just like what https://github.com/torvalds/linux/blob/master/drivers/i2c/busses/i2c-npcm7xx.c#L2043
shows.

Since there are cases that the i2c_recover_bus gets called at the
early stage of the function npcm_i2c_master_xfer,
the address is stored with the shift and used in the i2c_recover_bus call.

> > I'll write some comments about the left-shifted by one bit behavior
> > above this modification in next patch set.
>
> --
> With Best Regards,
> Andy Shevchenko
>
>

Thank you.

Regards,
Tyrone
diff mbox series

Patch

diff --git a/drivers/i2c/busses/i2c-npcm7xx.c b/drivers/i2c/busses/i2c-npcm7xx.c
index 68f3d47323ab..67d156ed29b9 100644
--- a/drivers/i2c/busses/i2c-npcm7xx.c
+++ b/drivers/i2c/busses/i2c-npcm7xx.c
@@ -2155,6 +2155,7 @@  static int npcm_i2c_master_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
 
 	} while (time_is_after_jiffies(time_left) && bus_busy);
 
+	bus->dest_addr = slave_addr << 1;
 	if (bus_busy || bus->ber_state) {
 		iowrite8(NPCM_I2CCST_BB, bus->reg + NPCM_I2CCST);
 		npcm_i2c_reset(bus);
@@ -2163,7 +2164,6 @@  static int npcm_i2c_master_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
 	}
 
 	npcm_i2c_init_params(bus);
-	bus->dest_addr = slave_addr;
 	bus->msgs = msgs;
 	bus->msgs_num = num;
 	bus->cmd_err = 0;