Hi Claudiu,
On Fri, Sep 15, 2023 at 7:51 AM claudiu beznea <claudiu.beznea@xxxxxxxxx> wrote:
> On 14.09.2023 16:12, Geert Uytterhoeven wrote:
> > On Tue, Sep 12, 2023 at 6:52 AM Claudiu <claudiu.beznea@xxxxxxxxx> wrote:
> >> From: Claudiu Beznea <claudiu.beznea.uj@xxxxxxxxxxxxxx>
> >>
> >> spinlock in rzg2l_mod_clock_endisable() is intended to protect the accesses
> >> to hardware register. There is no need to protect the instructions that set
> >> temporary variable which will be then written to register. Thus limit the
> >> spinlock only to the hardware register access.
> >>
> >> Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@xxxxxxxxxxxxxx>
> >
> > Thanks for your patch!
> >
> >> --- a/drivers/clk/renesas/rzg2l-cpg.c
> >> +++ b/drivers/clk/renesas/rzg2l-cpg.c
> >> @@ -912,13 +912,13 @@ static int rzg2l_mod_clock_endisable(struct clk_hw *hw, bool enable)
> >>
> >> dev_dbg(dev, "CLK_ON %u/%pC %s\n", CLK_ON_R(reg), hw->clk,
> >> enable ? "ON" : "OFF");
> >> - spin_lock_irqsave(&priv->rmw_lock, flags);
> >>
> >> value = bitmask << 16;
> >> if (enable)
> >> value |= bitmask;
> >> - writel(value, priv->base + CLK_ON_R(reg));
> >>
> >> + spin_lock_irqsave(&priv->rmw_lock, flags);
> >> + writel(value, priv->base + CLK_ON_R(reg));
> >> spin_unlock_irqrestore(&priv->rmw_lock, flags);
> >
> > After this, it becomes obvious there is nothing to protect at all,
> > so the locking can just be removed from this function?
>
> I tend to be paranoid when writing to hardware resources thus I kept it.
> Would you prefer to remove it at all?
Yes please. I guess this was copied from R-Car and friends, where
there is a RMW operation on an MSTPCR register.
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
