[PATCH] clk: fix ccf_clk_get_rate

[Michael Nazzareno Trimarchi]

Hi

On Thu, Jul 25, 2024 at 11:58 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 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?
>

unit test suggest that error condition are evaluated so we have 32 bit
on arm of unsigned long so we can not
map all the positive clock

rate = clk_set_rate(clk, 80000000);
ut_asserteq(rate, -ENOSYS);

Now, can we have a clock greater then 2Ghz if yes this not work always
on 32 bit, then the macro
IS_ERR_VALUE should help on clk return

Michael




> Thanks,
> Zhiqiang



--
Michael Nazzareno Trimarchi
Co-Founder & Chief Executive Officer
M. +39 347 913 2170
michael at amarulasolutions.com
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