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From: Wolfram Sang <wsa@the-dreams.de>
To: linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH] i2c: allow building emev2 without slave mode again
Date: Sat, 12 Dec 2015 16:20:57 +0000	[thread overview]
Message-ID: <20151212162057.GA1530@katana> (raw)
In-Reply-To: <2592093.cGKEcKVqLU@wuerfel>

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Hi Arnd,

thanks for looking into this, but I don't get your point yet.

> The slave_cb callback function is supposed to set the 'value'
> here,

Only if a master wants to READ from us.

> but it might return an error not assign the pointer,

An error is only returned if a WRITE from a master was not accepted by
the slave backend.

> It might be best to change the callback to return 'void' and not
> allow it to fail.

We need that because in case of an errno, the slave should send NACK to
the master instead of ACK.

> At least the eeprom slave cannot fail anyway, and it is the only
> implementation we have at the moment.

True. But giving a slave the possibility to NACK a write should be
present IMO.

> Alternatively, the  inline could return an error, and both bus
> drivers check for the error before using 'value'.

Hum, it does return an error?

	return client->slave_cb(client, event, val);

You probably mean something else?

Regards,

   Wolfram


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WARNING: multiple messages have this Message-ID (diff)
From: Wolfram Sang <wsa@the-dreams.de>
To: Arnd Bergmann <arnd@arndb.de>
Cc: "kbuild test robot" <lkp@intel.com>,
	kbuild-all@01.org, linux-i2c@vger.kernel.org,
	"Niklas Söderlund" <niklas.soderlund+renesas@ragnatech.se>,
	linux-sh@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH] i2c: allow building emev2 without slave mode again
Date: Sat, 12 Dec 2015 17:20:57 +0100	[thread overview]
Message-ID: <20151212162057.GA1530@katana> (raw)
In-Reply-To: <2592093.cGKEcKVqLU@wuerfel>

[-- Attachment #1: Type: text/plain, Size: 964 bytes --]

Hi Arnd,

thanks for looking into this, but I don't get your point yet.

> The slave_cb callback function is supposed to set the 'value'
> here,

Only if a master wants to READ from us.

> but it might return an error not assign the pointer,

An error is only returned if a WRITE from a master was not accepted by
the slave backend.

> It might be best to change the callback to return 'void' and not
> allow it to fail.

We need that because in case of an errno, the slave should send NACK to
the master instead of ACK.

> At least the eeprom slave cannot fail anyway, and it is the only
> implementation we have at the moment.

True. But giving a slave the possibility to NACK a write should be
present IMO.

> Alternatively, the  inline could return an error, and both bus
> drivers check for the error before using 'value'.

Hum, it does return an error?

	return client->slave_cb(client, event, val);

You probably mean something else?

Regards,

   Wolfram


[-- Attachment #2: Digital signature --]
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WARNING: multiple messages have this Message-ID (diff)
From: wsa@the-dreams.de (Wolfram Sang)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH] i2c: allow building emev2 without slave mode again
Date: Sat, 12 Dec 2015 17:20:57 +0100	[thread overview]
Message-ID: <20151212162057.GA1530@katana> (raw)
In-Reply-To: <2592093.cGKEcKVqLU@wuerfel>

Hi Arnd,

thanks for looking into this, but I don't get your point yet.

> The slave_cb callback function is supposed to set the 'value'
> here,

Only if a master wants to READ from us.

> but it might return an error not assign the pointer,

An error is only returned if a WRITE from a master was not accepted by
the slave backend.

> It might be best to change the callback to return 'void' and not
> allow it to fail.

We need that because in case of an errno, the slave should send NACK to
the master instead of ACK.

> At least the eeprom slave cannot fail anyway, and it is the only
> implementation we have at the moment.

True. But giving a slave the possibility to NACK a write should be
present IMO.

> Alternatively, the  inline could return an error, and both bus
> drivers check for the error before using 'value'.

Hum, it does return an error?

	return client->slave_cb(client, event, val);

You probably mean something else?

Regards,

   Wolfram

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  parent reply	other threads:[~2015-12-12 16:20 UTC|newest]

Thread overview: 52+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-12-10 13:14 [PATCH] i2c: allow building emev2 without slave mode again Arnd Bergmann
2015-12-10 13:14 ` Arnd Bergmann
2015-12-10 13:14 ` Arnd Bergmann
2015-12-10 13:34 ` Wolfram Sang
2015-12-10 13:34   ` Wolfram Sang
2015-12-10 13:34   ` Wolfram Sang
2015-12-10 13:51   ` Arnd Bergmann
2015-12-10 13:51     ` Arnd Bergmann
2015-12-10 13:51     ` Arnd Bergmann
2015-12-10 13:51     ` Arnd Bergmann
2015-12-10 14:54 ` kbuild test robot
2015-12-10 14:54   ` kbuild test robot
2015-12-10 14:54   ` kbuild test robot
2015-12-10 15:06   ` Arnd Bergmann
2015-12-10 15:06     ` Arnd Bergmann
2015-12-10 15:06     ` Arnd Bergmann
2015-12-10 15:06     ` Arnd Bergmann
2015-12-10 15:17     ` Wolfram Sang
2015-12-10 15:17       ` Wolfram Sang
2015-12-10 15:17       ` Wolfram Sang
2015-12-12 16:20     ` Wolfram Sang [this message]
2015-12-12 16:20       ` Wolfram Sang
2015-12-12 16:20       ` Wolfram Sang
2015-12-12 21:05       ` Arnd Bergmann
2015-12-12 21:05         ` Arnd Bergmann
2015-12-12 21:05         ` Arnd Bergmann
2015-12-12 21:05         ` Arnd Bergmann
2015-12-13  9:09         ` Wolfram Sang
2015-12-13  9:09           ` Wolfram Sang
2015-12-13  9:09           ` Wolfram Sang
2015-12-14 12:02           ` Arnd Bergmann
2015-12-14 12:02             ` Arnd Bergmann
2015-12-14 12:02             ` Arnd Bergmann
2015-12-14 13:52             ` Wolfram Sang
2015-12-14 13:52               ` Wolfram Sang
2015-12-14 13:52               ` Wolfram Sang
2015-12-14 22:27               ` Arnd Bergmann
2015-12-14 22:27                 ` Arnd Bergmann
2015-12-14 22:27                 ` Arnd Bergmann
2015-12-17 12:01                 ` Wolfram Sang
2015-12-17 12:01                   ` Wolfram Sang
2015-12-17 12:01                   ` Wolfram Sang
2015-12-17 14:48                   ` Arnd Bergmann
2015-12-17 14:48                     ` Arnd Bergmann
2015-12-17 14:48                     ` Arnd Bergmann
2015-12-17 19:40                     ` Wolfram Sang
2015-12-17 19:40                       ` Wolfram Sang
2015-12-17 19:40                       ` Wolfram Sang
2015-12-17 19:57                       ` Arnd Bergmann
2015-12-17 19:57                         ` Arnd Bergmann
2015-12-17 19:57                         ` Arnd Bergmann
2015-12-17 19:57                         ` Arnd Bergmann

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