From: Wolfgang Grandegger <wg@grandegger•com>
To: Wolfram Sang <w.sang@pengutronix•de>
Cc: Devicetree-discuss@lists•ozlabs.org,
Linuxppc-dev@lists•ozlabs.org, Linux-i2c@vger•kernel.org,
Wolfgang Grandegger <wg@denx•de>
Subject: Re: [PATCH 2/3] i2c-mpc: add support for the MPC512x processors from Freescale
Date: Mon, 25 Jan 2010 19:33:31 +0100 [thread overview]
Message-ID: <4B5DE3FB.10505@grandegger.com> (raw)
In-Reply-To: <20100125151509.GD5257@pengutronix.de>
Wolfram Sang wrote:
>>>>
>>>> -static void __devinit mpc_i2c_setclock_52xx(struct device_node *node,
>>>> - struct mpc_i2c *i2c,
>>>> - u32 clock, u32 prescaler)
>>>> +static void __devinit mpc_i2c_setup_52xx(struct device_node *node,
>>>> + struct mpc_i2c *i2c,
>>>> + u32 clock, u32 prescaler)
>>>> {
>>>> int ret, fdr;
>>>>
>>>> + if (clock == -1) {
>>> Could we use 0 for 'no_clock'? This would make the above statement simply
>> "0" is already used to maintain backward compatibility setting a safe
>> divider.
>
> Ah, now I see:
>
> 'clock == -1' means 'preserve clocks' (and is checked here in mpc_i2c_setup_52xx())
Yes, this is now necessary because "setup" does not just do clock settings.
> 'clock == 0' means 'safe divider' (and is checked in mpc_i2c_get_fdr_52xx())
This is for compatibility with old DTS files and last time it was tricky
to get that right and therefore...
> This is not a beauty ;)
>
> What about adding a flags variable to the setup-functions?
.. I hesitate to make bigger changes to the code flow, which the
introduction of a flags variable would required. Also it seems to be
overkill to me. I will have a closer look, though. At a minimum I will
replace "-1" with "MPC_I2C_PRESERVE_CLOCK".
Wolfgang.
next prev parent reply other threads:[~2010-01-25 18:33 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-01-25 8:27 [PATCH 0/3] i2c-mpc: add support for the Freescale MPC512x and other fixes Wolfgang Grandegger
2010-01-25 8:27 ` [PATCH 1/3] i2c-mpc: use __devinit[data] for initialization functions and data Wolfgang Grandegger
2010-01-25 8:27 ` [PATCH 2/3] i2c-mpc: add support for the MPC512x processors from Freescale Wolfgang Grandegger
2010-01-25 8:27 ` [PATCH 3/3] powerpc: doc/dts-bindings: update doc of FSL I2C bindings Wolfgang Grandegger
2010-01-25 11:56 ` Wolfram Sang
2010-01-25 11:58 ` Wolfgang Grandegger
2010-01-25 11:52 ` [PATCH 2/3] i2c-mpc: add support for the MPC512x processors from Freescale Wolfram Sang
2010-01-25 12:06 ` Wolfgang Grandegger
2010-01-25 15:15 ` Wolfram Sang
2010-01-25 18:33 ` Wolfgang Grandegger [this message]
2010-01-25 20:48 ` Wolfram Sang
2010-01-25 20:54 ` Wolfgang Grandegger
2010-01-25 21:09 ` Wolfram Sang
2010-01-26 14:39 ` Ben Dooks
2010-01-26 18:44 ` Wolfgang Grandegger
2010-01-25 12:02 ` [PATCH 0/3] i2c-mpc: add support for the Freescale MPC512x and other fixes Wolfram Sang
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