2022-03-03 10:27:26

by Tyrone Ting

Subject: [PATCH v3 03/11] i2c: npcm: Fix client address calculation

From: Tali Perry <[email protected]>

Fix i2c client address by left-shifting 1 bit before
applying it to the data register.

Fixes: 56a1485b102e ("i2c: npcm7xx: Add Nuvoton NPCM I2C controller driver")
Signed-off-by: Tali Perry <[email protected]>
Signed-off-by: Tyrone Ting <[email protected]>
---
drivers/i2c/busses/i2c-npcm7xx.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/i2c/busses/i2c-npcm7xx.c b/drivers/i2c/busses/i2c-npcm7xx.c
index 2ad166355ec9..4c225e1a058f 100644
--- a/drivers/i2c/busses/i2c-npcm7xx.c
+++ b/drivers/i2c/busses/i2c-npcm7xx.c
@@ -2131,7 +2131,7 @@ 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->dest_addr = slave_addr << 1;
bus->msgs = msgs;
bus->msgs_num = num;
bus->cmd_err = 0;
--
2.17.1

2022-03-03 11:33:54

by Andy Shevchenko

Subject: Re: [PATCH v3 03/11] i2c: npcm: Fix client address calculation

On Thu, Mar 03, 2022 at 04:31:33PM +0800, Tyrone Ting wrote:
> From: Tali Perry <[email protected]>
>
> Fix i2c client address by left-shifting 1 bit before
> applying it to the data register.

...

> - bus->dest_addr = slave_addr;
> + bus->dest_addr = slave_addr << 1;

1. Why this is not using i2c_8bit_addr_from_msg() helper?
2. This is duplication of what npcm_i2c_master_start_xmit() does.

Taking 2 into account, what is this exactly fixing?
Sounds like a red herring.

--
With Best Regards,
Andy Shevchenko

2022-03-04 20:29:10

by Tyrone Ting

Subject: Re: [PATCH v3 03/11] i2c: npcm: Fix client address calculation

Hi Andy:

Thank you for your comment and it'll be addressed.

Andy Shevchenko <[email protected]> 於 2022年3月3日 週四 下午6:31寫道：
>
> On Thu, Mar 03, 2022 at 04:31:33PM +0800, Tyrone Ting wrote:
> > From: Tali Perry <[email protected]>
> >
> > Fix i2c client address by left-shifting 1 bit before
> > applying it to the data register.
>
> ...
>
> > - bus->dest_addr = slave_addr;
> > + bus->dest_addr = slave_addr << 1;
>
> 1. Why this is not using i2c_8bit_addr_from_msg() helper?
> 2. This is duplication of what npcm_i2c_master_start_xmit() does.
>
> Taking 2 into account, what is this exactly fixing?
> Sounds like a red herring.
>
> --
> With Best Regards,
> Andy Shevchenko
>
>

Best regards,
Tyrone