[PATCH] clk: fix ccf_clk_get_rate

[Z.Q. Hou]

Hi Michael,

> -----Original Message-----
> From: Michael Nazzareno Trimarchi <michael at amarulasolutions.com>
> Sent: Thursday, July 25, 2024 5:26 PM
> To: Z.Q. Hou <zhiqiang.hou at nxp.com>; Simon Glass <sjg at chromium.org>
> Cc: u-boot at lists.denx.de; trini at konsulko.com; lukma at denx.de;
> seanga2 at gmail.com
> Subject: Re: [PATCH] clk: fix ccf_clk_get_rate
> 
> Hi
> 
> On Thu, Jul 25, 2024 at 10:53 AM Z.Q. Hou <zhiqiang.hou at nxp.com> wrote:
> >
> > Hi Michael,
> >
> > > -----Original Message-----
> > > From: Michael Nazzareno Trimarchi <michael at amarulasolutions.com>
> > > Sent: Thursday, July 25, 2024 3:32 PM
> > > To: Z.Q. Hou <zhiqiang.hou at nxp.com>
> > > Cc: u-boot at lists.denx.de; trini at konsulko.com; lukma at denx.de;
> > > seanga2 at gmail.com
> > > Subject: Re: [PATCH] clk: fix ccf_clk_get_rate
> > >
> > > Hi
> > >
> > > On Thu, Jul 25, 2024 at 9:16 AM Zhiqiang Hou <Zhiqiang.Hou at nxp.com>
> > > wrote:
> > > >
> > > > From: Hou Zhiqiang <Zhiqiang.Hou at nxp.com>
> > > >
> > > > As the type of return value is 'ulong', when clk_get_by_id()
> > > > failed, it should return 0 to indicate the get_rate operation doesn't
> succeed.
> > > >
> > >
> > > I understand your point here but the clk_get_rate that can call the
> > > ccf clk_get_rate can already return -ENOSYS.
> >
> > will also fix it.
> >
> 
> Is there any usage of the error set on the latest bit of the clock? We need to
> be sure that this is correct use accross the uboot. The clk-uclass define the
> error that can return

The problem is this function's return value is 'ulong', if use the error set, the caller will treat it as a good value instead of a error number. There are several APIs have the same problem.

2 methods to fix it:
1. keep the API's prototype, and use '0' to indicate error condition, but a real '0' return value is also considered as error.
2. Change the return type to like 'long long int', and use a negative error number to indicate error condition. Need to update the check of return value for all the callers.

Any suggestion?

Thanks,
Zhiqiang