> Subject: Re: [PATCH 1/2] clk: imx93: Drop macro IMX93_CLK_END
>
> On 28/06/2024 03:17, Peng Fan wrote:
> >> Subject: Re: [PATCH 1/2] clk: imx93: Drop macro IMX93_CLK_END
> >>
> >> On 25/06/2024 12:43, Pengfei Li wrote:
> >>> On Tue, Jun 25, 2024 at 09:44:42AM +0200, Krzysztof Kozlowski
> >> wrote:
> >>>> On 25/06/2024 19:51, Pengfei Li wrote:
> >>>>> IMX93_CLK_END was previously defined in imx93-clock.h to
> >> indicate
> >>>>> the number of clocks, but it is not part of the ABI, so it should
> >>>>> be dropped.
> >>>>>
> >>>>> Now, the driver gets the number of clks by querying the
> maximum
> >>>>> index in the clk array. Due to the discontinuity in the definition
> >>>>> of clk index, with some gaps present, the total count cannot be
> >>>>> obtained by summing the array size.
> >>>>>
> >>>>> Signed-off-by: Pengfei Li <pengfei.li_1@xxxxxxx>
> >>>>> ---
> >>>>> drivers/clk/imx/clk-imx93.c | 25 +++++++++++++++++++++----
> >>>>> 1 file changed, 21 insertions(+), 4 deletions(-)
> >>>>>
> >>>>> diff --git a/drivers/clk/imx/clk-imx93.c
> >>>>> b/drivers/clk/imx/clk-imx93.c index
> c6a9bc8ecc1f..68c929512e16
> >>>>> 100644
> >>>>> --- a/drivers/clk/imx/clk-imx93.c
> >>>>> +++ b/drivers/clk/imx/clk-imx93.c
> >>>>> @@ -257,6 +257,20 @@ static const struct imx93_clk_ccgr
> >> { static
> >>>>> struct clk_hw_onecell_data *clk_hw_data; static struct clk_hw
> >>>>> **clks;
> >>>>>
> >>>>> +static int imx_clks_get_num(void) {
> >>>>> + u32 val = 0;
> >>>>> + int i;
> >>>>> +
> >>>>> + for (i = 0; i < ARRAY_SIZE(root_array); i++)
> >>>>> + val = max_t(u32, val, root_array[i].clk);
> >>>>> +
> >>>>> + for (i = 0; i < ARRAY_SIZE(ccgr_array); i++)
> >>>>> + val = max_t(u32, val, ccgr_array[i].clk);
> >>>>> +
> >>>>> + return val + 1;
> >>>>> +}
> >>>>> +
> >>>>> static int imx93_clocks_probe(struct platform_device *pdev) {
> >>>>> struct device *dev = &pdev->dev; @@ -264,14 +278,17 @@
> static
> >>>>> int imx93_clocks_probe(struct
> >> platform_device *pdev)
> >>>>> const struct imx93_clk_root *root;
> >>>>> const struct imx93_clk_ccgr *ccgr;
> >>>>> void __iomem *base, *anatop_base;
> >>>>> + int clks_num;
> >>>>> int i, ret;
> >>>>>
> >>>>> + clks_num = imx_clks_get_num();
> >>>>> +
> >>>>> clk_hw_data = devm_kzalloc(dev, struct_size(clk_hw_data,
> >> hws,
> >>>>> - IMX93_CLK_END),
> >> GFP_KERNEL);
> >>>>> + clks_num), GFP_KERNEL);
> >>>>> if (!clk_hw_data)
> >>>>> return -ENOMEM;
> >>>>>
> >>>>> - clk_hw_data->num = IMX93_CLK_END;
> >>>>> + clk_hw_data->num = clks_num;
> >>>>
> >>>> Why so complicated code instead of pre-processor define or array
> >> size?
> >>>>
> >>>> Best regards,
> >>>> Krzysztof
> >>>>
> >>>>
> >>>
> >>> Hi Krzysztof,
> >>>
> >>> Thanks for the comment, here are some of our thoughts.
> >>>
> >>> Regarding the predefined method, it's easy to forget to update the
> >>> macro definition when adding some new clocks to imx93-clock.h in
> >> the future.
> >>
> >> Somehow most developers in most platforms can do it... Anyway,
> that
> >> would be build time detectable so no problem at all.
> >>
> >>>
> >>> Also, we cannot use the array size method in this scenario, as some
> >>> unnecessary clocks have been removed in the past, resulting in
> >>> discontinuous definitions of clock indexes. This means that the
> >>> maximum clock index can be larger than the allocated clk_hw
> array
> >> size. At this point, using the maximum index to access the clk_hw
> >> array will result in an out of bounds error.
> >>
> >> You mix bindings with array entries. That's independent or just clock
> >> drivers are broken.
> >
> > But there is issue that binding update and clock driver are normally
> > in two patches. So if just use the IMX93_CLK_END in this file, it
> > will be easy to break `git bisect`.
>
> There is no issue. Srsly, this would be the only, only one driver having
> that issue.
>
> How is this even possible? How adding one new define for pre-
> processor would cause driver issues or some sort of bisectability
> problems?
Ah, I was wrong, I just thought driver update is applied first.
With binding update applied first, then driver update applied,
there is no issue.
Regards,
Peng.
>
> These are basics of C we talk about now...
>
> Best regards,
> Krzysztof
>
