Re: [PATCH v2 2/4] hwrng: stm32 - implement support for STM32MP25x platforms

[Marek Vasut]

On 10/14/24 2:36 PM, Gatien CHEVALLIER wrote:
> On 10/14/24 10:52, Marek Vasut wrote:
> > On 10/14/24 10:38 AM, Gatien CHEVALLIER wrote:
> > > On 10/11/24 18:17, Marek Vasut wrote:
> > > > On 10/11/24 5:41 PM, Gatien Chevallier wrote:
> > > >
> > > > [...]
> > > >
> > > > > @@ -551,6 +565,41 @@ static int stm32_rng_probe(struct 
> > > > > platform_device *ofdev)
> > > > >       priv->rng.read = stm32_rng_read;
> > > > >       priv->rng.quality = 900;
> > > > > +    if (!priv->data->nb_clock || priv->data->nb_clock > 2)
> > > > > +        return -EINVAL;
> > > > > +
> > > > > +    priv->clk_bulk = devm_kzalloc(dev, priv->data->nb_clock * 
> > > > > sizeof(*priv->clk_bulk),
> > > > > +                      GFP_KERNEL);
> > > > > +    if (!priv->clk_bulk)
> > > > > +        return -ENOMEM;
> > > >
> > > > Try this:
> > > >
> > > > ret = devm_clk_bulk_get(dev, priv->data->nb_clock, priv->clk_bulk);
> > > > ...
> > > > // Swap the clock if they are not in the right order:
> > > > if (priv->data->nb_clock == 2 &&
> > > >      strcmp(__clk_get_name(priv->clk_bulk[0].clk), "core"))
> > > > {
> > > >   const char *id = priv->clk_bulk[1].id;
> > > >   struct clk *clk = priv->clk_bulk[1].clk;
> > > >   priv->clk_bulk[1].id = priv->clk_bulk[0].id;
> > > >   priv->clk_bulk[1].clk = priv->clk_bulk[0].clk;
> > > >   priv->clk_bulk[0].id = id;
> > > >   priv->clk_bulk[0].clk = clk;
> > > > }
> > >
> > > Hi Marek,
> > >
> > > This won't work as the name returned by this API is clk->core->name.
> > > AFAICT, it doesn't correspond to the names present in the device tree
> > > under the "clock-names" property.
> > > Any other idea or are you fine with what's below?
> > Hmmm, it is not great, but at least it reduces the changes throughout 
> > the driver, so that is an improvement.
> >
> > I guess one could do some of_clk_get() and clk_is_match() in probe to 
> > look up the clock in OF by name and then compare which clock is which 
> > before swapping them in clk_bulk[] array, but that might be too 
> > convoluted?
>
> Yes, probably too much. What's present in the patch is not close to
> perfection but has the advantage of being straightforward. If we agree
> on that, I'll send a V3 containing the modifications in the bindings
> file.
Errr, I'm sorry, maybe there is a way to do this better. Look at 
drivers/clk/clk-bulk.c :

 15 static int __must_check of_clk_bulk_get(struct device_node *np, int 
num_clks,
 16                                         struct clk_bulk_data *clks)
 17 {
 18         int ret;
 19         int i;
 20
 21         for (i = 0; i < num_clks; i++) {
 22                 clks[i].id = NULL;
 23                 clks[i].clk = NULL;
 24         }
 25
 26         for (i = 0; i < num_clks; i++) {
 27                 of_property_read_string_index(np, "clock-names", i, 
&clks[i].id);
 28                 clks[i].clk = of_clk_get(np, i);

If I read this right, then clks[i].id should be the DT clock name. So 
the swap conditional above could use .id to identify whether the first 
position is core clock or not, like this:

if (priv->data->nb_clock == 2 &&
    strcmp(__clk_get_name(priv->clk_bulk[0].id), "core"))
                                            ^^

You might need to use devm_clk_bulk_get_all() to access the 
of_clk_bulk_get() .

Or am I missing something still ?